As a TTX rider, this is nice to see. However, without ANY configuration data, it's less useful. I.e., you don't know what bottles were or were not on the frame. What wheels, etc. I hope he provides some more info. Otherwise, it's just marketing speak, as much as I'd like to stand up and shout "yes." The TTX is a very well designed, very well executed frame. I think at the very least, you can take away that it is among the very best frames in the world. I think there is a clear group of frames at the top, and the TTX and P3C are both part. The Scott Plasma, it appears, is not. Based on a very cursory inspection of the downtube and headtube of all thread bikes, I will say that it doesn't surprise me a whole lot. There are some very simple, very fundamental rules of aerodynamics that you need to follow. If you follow them, you'll do well. Some companies do this in house with CFD and lots of windtunnel testing. Others do it by just copying the tubes of the companies that spend that money. And others still don't, for whatever reason, do this at all, something which I fail to understand.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Hey Rappstar, how much will the way the rider's body affecting the airflow change the raw bike's aerodynamics. I'd imagine that is completely possible that riding knees in vs knees apart could affect the relative benefits of a P3C type cutout vs some other bike. Also, if I recall correctly, John Cobb once showed that when riding a softride it was better to go downhill in a tuck with your knees actually clamped to the top tube/beam but instead apart. The idea was that the air could reattack better behind the legs when apart than when together touching the top tube. Of course, this would not apply to a conventional bike, however it goes to show that rider position and style might also affect the aero benefits from one bike vs another, adding to or negating a particular bike's positive qualities?

haha sweet, my Madone is only ~50g less aero than a Scott Plasma.

It's certainly possible. I'm definitely not any sort of authority of rider/frame aerodynamics (frame aerodynamics are governed much more by the fundamentals of aerodynamics, whereas the rider/frame interaction is something where there is no real substitute for just going to the tunnel). But things could certainly be affected. For instance, Lieto rides very slack, so perhaps his legs are in a different position relative to the seattube than say Dave Zabriskie's on the P3C, where Dave is sitting way on the nose of the saddle. So this might, as a total guess, affect the airflow around the seattube, which might reduce some of the effectiveness of the P3C's shape there. If you go by the theory that the P3C is designed to be ridden steep, I'd also be willing to give Gerard the benefit of the doubt that they focused on the aerodynamics of a rider in such a position. I can imagine, though I want to emphasize that this is total guessing, that if the P3C is optimized geometrically for steep riding, it may also be optimized aerodynamically. The Trek is also designed to be ridden steep, but perhaps not to quite the same extent, so perhaps the aerodynamics of the frame work better with someone who rides slack. The geometries are close, but not identical, so it's certainly reasonable, I think, to infer that there may be a "right bike" for a rider based on fit, and then furthermore based on aerodynamics. I.e., if you know that 4 or 5 of 10 high-end bikes work with your position geometrically, you might further be able to refine that number down with windtunnel testing to the one or two bike(s) that are basically a perfect match. I believe they did this with David Millar's (tainted) World TT win. They built the bike entirely around him, both in terms of geometry, and in terms of tuning the aerodynamics around his position (at least, that is how I interpreted the article I read on the project).

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Thanks, I just wanted the aero gurus to confirm that rider position on an aero bike can affect the "aero contribution" of the bike itself.

I'm taking a wild shot here, but I'd wager to guess that the further apart your knees are, the more the benefit of the aero cut. Bring the knees in and there is no laminar air hitting the aero cutout, however, you are punching a smaller aggregate hole in the wind, so overall Cda might be better even though contribution for the aero cutout is now substantially reduced. Just a guess.

Dev

Number one...will you all please stop letting science get in the way of our purchases!


Second...I am willing to bet that the person to win Kona will be the one who is most fit...no matter what bike they ride....


Three...golly jeepers I hope it is Pink!

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What if the Hokey Pokey is what it is all about?

I agree, that being said, wh was the world TT champs won on a p3c???? :)

With the P3C, TTX, BMC, or DA how much are they just splitting hairs as to which is the fastest bike? Intentionally omitted Specialized, Ordu, new Slice, Willier since they are very new designs and haven't seen any data or anecdotal evidence on them. Walser could probably be added but was not because to the best of my knowledge is not a mass production design ( Is mass production of a niche market a real term?)

Also, you seem to know a few people, is the Bontrager bottle on the front of Lieto's bike a one off, pre-production, test, Dremel-mod?

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Brawndo's got what plants crave. Brawndo's got electrolytes. And that's what plants crave. They crave electrolytes. Which is what Brawndo has. And that's why plants crave Brawndo. Not water, like from the toilet.

Really!?!

So you suggest that I might benefit more from better/harder/smarter training than from buying "fast" bikes?
Why wasn't that absolute brand-new never-heard-before information available earlier in my triathlon life?
That would have saved me buying all those expensive bikes.

Frank

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I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched C-beams glitter in the dark near the Tannhauser Gate. All those moments will be lost in time like tears in rain.

this article states the data is from a wind tunnel test of Levi Leipheimer on Feb. 26th, 2007.

http://www.bikeradar.com/...x-99-ssl-12746?img=2

Low Speed Wind Tunnel test figures based on Levi Leipheimer's February 26, 2007 wind tunnel run (Trek©.)

• 
• 

The bottle and cage are both available now. I can't tell if that is a new cage designed to be bar mounted, or if it is a custom fit...

In any event, it looks pretty cool!

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______________________________________________
DING DING!! Artmus speaks the truth!
100 miles a day is the only power meter you need.

The stats are not for the TTX, but rather the new TTX SSL. Levi and company looked pretty good on them on the way to Paris. Chris has one too. Not many other people, unless it says prototype on it. The SSL has 300 grams less frame weight than the 9.9 TTX. That's pretty good fine tuning of a proven fast product. It is hard to get one though, and the price reflects that the Waterloo factory is not going to make many. But it does show me that the 800 lb. gorilla in cycling is not resting. When Porsche finishes up a model year production run, the marketing dept. throws all kinds of horsepower and performance specials into a special "S' model to enhance the brand status and give the company engineers a chance to show their stuff when startup model costs have long been paid for. I think Trek is not betting on a $8200 bike to add to their bottom line, but has created a flagship to help TTX 9 series sales late in their production run. They are great bikes, backed by a company that stands behind it's product. I wish Chris the best in Kona, and I am rooting for him and Trek.

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"The trick, William Potter, is not minding that it hurts." T.E. Lawrence

These data remind me of Gerard's comment that "we're always happy to finish 2nd in tests paid for by other manufacturers". :-)

To say a bike is fast is to imply the bike propels itself, which is absurd.

NEXT!

Ummm...aerodynamically speaking (i.e. the "stats" shown in that plot), the TTX and TTX SSL will be identical.

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http://bikeblather.blogspot.com/

I'm constantly amazed at the resiliency of these threads on ST. Bottom line: the difference in aero performance of the top bikes is negligible, and more than canceled out by body position and/or the strength of the rider. So why must we continue to post wind tunnel tests, charts graphs, etc. when it really doesn't matter? Is it because it's the off-season?

300 grams less for the frame? Frame was not really heavy to begon with. As I recall a little over 1400 grams. But the 660 gram fork??? Did they do anything about that?

IMO, it's because doing well in timed cycling events ( i.e. TTs or Tri bike legs) is ALL about attention to a BUNCH of little details. This is one of those details. It's up to the person looking at the numbers to decide if they are significant enough to worry about. They, and they alone, get to decide if it "matters".

Personally, I'm constantly amazed at how many people think that none of this stuff "matters" ;-)

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http://bikeblather.blogspot.com/

So many variables in something like this that the information needs a lot of qualification- for either manufacturer.

One of the predominant factors is selecting a bike a rider can acheive an aerodynamic and efficient (watts vs. heart rate, etc) on. Then there are the variables of comfort and what affect that may/may not exert on the riders real performance on the road. A bike can be more efficient and more aerodynamic but if a rider is distracted by saddle discomfort by something as simple as a poor saddle choice that is likely to cost them time when they don't even realize it.

It concerns me when people try to grasp at informational straws like "which bike is more aero- here's a cool computer generated graph that "proves" it".

For us real people, the people on the sales floor selling and buying the bikes, it is key to remember a few things:

• If you don't feel comfortable on the bike, it will be difficult to focus on remaining still and putting in a good effort.
• When we are grinding up a steep hill at the local triathlon or on the bike course at Lake Placid, Wisconsin, Wildflower, St. Croix or whereever and going 9 m.p.h. with our hands on the base bars seated upright trying to save a few precious seconds on a climg aerodynamics is a greatly diminished factor: Other issues like fit, frame stiffness, crank and component selection, pedal set up, tire choice become more important concerns in the real world.
• We don't have wind tunnels to develop the optimal position, so what is the easiest bike to get a resonable position that is a good mix of aerodynamic, comfort, power and with good bike handling? That answer may vary from person to person contingent on size, dimensions, riding style, level of experience and fitness.

So many things go into what makes a bike optimal for a given individual. No one truly understands how all the variables interact. fixating on one aspect of the bike's performance (aerodynamics in this case) is an interesting and worthwhile discussion, but one that should be kept in perspective against the other factors that influence the performance of the bike/rider package.

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Tom Demerly
The Tri Shop.com

It's not that none of this stuff matters, it's that there is a point of diminishing returns. Once you get into the 5 or so most aero bikes, the difference between the aerodynamics of the frames is less important than whether someone rides with their knees inward or outward, etc. At that point, whether one riderless frame does .2% better in a wind tunnel (or other test) than the other is essentially meaningless.

It happens with all equipment based hobbies, part of the fun.

I remember reading years ago about a car race series. You had to buy a specific car and couldn't do any modiifications. You could take apart the car and do anything you wanted as long as the original parts met the manufacturers original specs for that part. One team consistently dominated year in year out, with different drivers. This was also the team owned by a machine shop owner who put 1000s of hours in to rebuilding the car. Every part was lightened to the bottom of the acceptable limit, polished balanced etc. Nothing they did was a big deal on any 1 part, but it all adds up.

Take the second most aero bike with the second best rolling tires, the second most aero wheels, the second heaviest drivetrain, the second fastest wet suit, second lightest shoes, etc and race against someone with the fastest / best of everything and, assuming you are relatively well matched, I know who I'm betting on.

Of course its not going to turn a mid pack ito a top tier guy.

Styrrell

Spoken like a real 'watt trader', Tom.....

Is it just me, or do those drag numbers not add up for a 130lb TT specialist??

Aside from "the devil is in the details" argument, there's also the fact that we wouldn't know that the differences between the very best aero bikes are quite small if the data were never shared.

Thousands of years ago, when our species was still evolving, obsessive and persistent acquisition of the very best weaponry (spears, clubs, arrows, etc.) was a trait that had tremendous survival value. For example, with a slightly improved spear, you could overwhelm an otherwise vastly superior foe, armed with the old, non-dimpled spear. So this trait was honed and bred into us through natural selection. Thus, in modern-day sport (i.e. sublimated warfare), it's only natural for us to hew to this strongly imprinted trait.


-jens

Or as my friend Brian Parr once laconically put it: "if we weren't doing this (racing bikes) we'd be off in the woods beating on each other with sticks and rocks."

the drag/speed numbers imply a Cda around 0.245-0.255. For a small guy like Levi that's surprisingly large. Perhaps he ought to hire Jens/Tom/AC as consultants :-)

If the numbers have been 'adjusted' to protect his true data that should have been stated ...

Something does not quite compute ... else my spreadsheet is just way off.

Yeah...a CdA of ~0.25 - 0.26 does seem a bit high for Levi. But, like I've said, not knowing the details of the comparison, it's tough to put any value on the differences shown in that chart. I'm thinking the comparison may actually have been from Basso (who would've had a P3C to compare to, right?).



I've pointed out to Druber the flaws in his "watt trader" or "purchasing watts" analogy. Here's what I told him is a better analogy:

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http://bikeblather.blogspot.com/

Yeah, I've stood next to Levi, and he's one of the only guys I've seen who make me feel big--and I'm in the sub .02 category! Something is fishy with those numbers?

As far as Druber, I beat a lot of guys like that simply because they cling to that attitude--so please, don't try to change his ways!

For another poster, Lieto's bottle set-up is a dremel job on the bottles themselves. The bottles are empty; he carries his fluids behind the seat in a custom Bontrager carrier.

Yes, those numbers are off if they are for Levi. Allied confirmed he tested at like 0.19, lowest they'd ever seen. You can find that somewhere.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Trek's press release stated they were for Levi ...

FWIW, 0.19 CdA would require equivalent test drag numbers in the 1475-1500g range.

Does Scott Daubert ever post here?

Hmm. As Colonel Klink used to say, "interesting.....veeerrrrryyyy interesting."

My guess would be that was a bit of "artistic license" based on the belief that more people have heard of Leipheimer than of Lieto (or whomever it was that was actually tested).

http://biz.yahoo.com/....pf=personal-finance


In any case, what do Cervelo have to say? ;-)

Thanks, I guess I'm just a dumbass, but I'm guessing that he found having the bottle on the front was better than nothing at all. I don't really understand that, but I'll take the word of people smarter then me. Nice touch with the straw coming out, that makes it not a fairing?

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Brawndo's got what plants crave. Brawndo's got electrolytes. And that's what plants crave. They crave electrolytes. Which is what Brawndo has. And that's why plants crave Brawndo. Not water, like from the toilet.

"Based on Levi Leipheimer’s February 26, 2007 wind tunnel run, which scored the lowest drag numbers ever recorded at the SDLSWT by a male athlete."

Like I said: interesting....veeeeeeeeerrrrrrrrrrryyyyyyyyyy interesting.

Wrong fictional German soldier:

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"Go yell at an M&M"

I thought that I already covered that? :-)

http://forum.slowtwitch.com/...post=1516581#1516581

okay .. the name Colby Pearce comes to mind ... just fishing .. .

Ack, you're right!

??

What do you find most interesting about the.019? Do you think that's low for Levi (I don't), or that they haven't tested any male athletes lower? He's pretty damn small. The only guy I can think of who's smaller (your arch enemy Kirk), and I wonder if he's even been to the tunnel.

On first mention, the fact that it was reported to be the lowest measured at San Diego.

On second mention, the fact that they felt it necessary to specify male athlete.

In any case, it doesn't surprise me at all that Leipheimer's CdA is around 0.19 m^2.

Nope, the frames are in fact different (at least 07 TTX vs. 08 TTX SSL; not sure if they made the changes to all TTX models for 08). New fork, new downtube placement, and some other changes. They cover them in the article.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

err .. thinking of a 'low aero drag' male candidate .. that's all ..

Oh, THAT bottle. I thought you were talking about his bottles on the frame, which are just dummys. I think the bottle up front is probably a functional bottle. Vineman, where that pic is taken, is a very well supported course, so you can make it the whole way with an aero bottle that you just refill at aid stations.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

As to why it matters...because when people go and buy a new bike, lots of people would rather spend the money on what is proven to be the fastest. They may not be right, but it definitely exists!

Colby's CdA is in that range even when using the set-up shown here:

http://www.cyclingnews.com/...ationals074/file0081

I wish I had the time to list all of the accomplishments, gold medals, podium places, and PR performances that are or could have been achieved with a 0.2% advantage.

I can think of a half dozen records on the track that were eclipsed or fell just short by a margin WELL below 0.2%

What was the total difference between Cadel and Levi in time in TTs in this year's TdF? Do you think Levi would like that 0.2%?

Another way to look at it, 0.2% is about a quarter mile over the course of a Ironman Bike course. Do you think the '06 results or at least the drama of the finish would change if you gave Macca that 1/4 mile leaving T2?

You can claim that it doesn't matter much, but once you concede that it does matter, there is no such thing as negligible, a difference by its very nature and being is important.


-SD

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https://www.kickstarter.com/...bike-for-the-new-era

Of all the people to reply to when making that statement, you pick me?

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Neither article, and most notably the Trek press release, says anything about changes between the '07 TTX and the '08 TTX SSL models besides the work done to lighten the frame. Then again, you have first hand experience with the 2 models, right? So...what are the differences?

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http://bikeblather.blogspot.com/

part of the confusion (here and in numerous other threads) is the generic use of "TTX". There are three basic model families, across a couple years of production:

TTX - the original, roadie geometry, 1-size only

Equinox TTX - inspired by the above, steeper geometry, several other diffferences (1.125 steertube fork, some tube shape deltas both subtle and obvious, etc)

Equinox TTX SSL - lightweight version of the above


I claim no knowledge of head-to-head aero differences between the first one and the following two. But absence of evidence is not evidence of absence :-)


Carl

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Carl Matson

That's what I find a bit odd about the graph. Tunnel time is expensive - who would bring two other essentially random bikes along to test? It's not like Lieto OR Basso OR Leipheimer would be in a position to say "you know what, I think I will ride the plasma this year" if it had tested faster. I guess I can see bringing the P3C for Trek's marketing purposes, but the plasma? It just seems weird to me.
Not to say that anyone involved in the production of this graph has done anything untoward, it just seems odd.

I guess I can see bringing the P3C for Trek's marketing purposes, but the plasma? It just seems weird to me.

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Isn't the Plasma supposed to be really light? I'm pretty sure Scott's saying something to that effect.

If so, maybe Trek is trying to say, "Look at the TTX, it's lighter than the Plasma and more aero than the P3C. Have your cake and eat it too!"

Carl, in the article, it says "Now we've opened the flood gates of debate there are a couple of key features that make the TTX an interesting Time machine. At the all important front a wider bladed fork blade allows air pulled along by the tyre, rim and spoke to pass more freely through the fork. This is most noticeable at the wider crown and the dropouts where the blades sit behind the hub end of the spokes. The smooth lines of the fork's crown are also designed to flow into the profile of the downtube. The lower downtube has also been placed in such a way as to minimize the gap between the front wheel. Cable routing is directed behind the stem and into the frame to complete the clean, aero flow at the front."

I bolded the stuff that is noted as being different. Now, is this a difference between the Equinox TTX and the original TTX? OR between the 07 TTX and the 08 TTX SSL?

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Which raises an interesting question: what are the odds that the bike was tested using a HED3? (I now need to go look again at that pic that Jens posted.)

It appears to be a Bontrager Aeolus front. Here's the whole article:

http://www.procyclingnews.com/...ullstory&id=4807

This is pretty clear about the comparison between the frames. They even matched up his outline on the screen to make sure he was in the same position on each frame



-- jens

Thanks - I thought as much after looking at the small pic you posted, but it's absolutely clear from the article.




Hmm...what about the claim that the bikes were set up identically, then? If you look closely at the pic of Basso on the P3C, it appears that that bike was fitted with VisionTech bars (which is what you'd expect, VisionTech being a sponsor of Basso's previous squad, i.e. CSC).

His wrist angle also appears different on the two bikes, but I'm less confident of that conclusion than the one above.

Aha! Photographic proof that my speculation (Basso for the data vs. Levi) about the rider subject has a firm basis. Of course, I can understand why Trek would be a bit hesitant to say that the numbers come from Basso...

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http://bikeblather.blogspot.com/

Hey Jens...can we "Tom Sawyer" you into pixel counting the drag history in this pic to see if the baseline on the P3C is higher by the amount claimed? :-)

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http://bikeblather.blogspot.com/

dang it Tom, don't they know we country folk can back-calculate CdA as well as 'dem town folk? And cipher out who's tiny and who's not?

 
Well, just putting my micrometer on the screen and measuring the ratio of the low point of the yellow drag history vs. the height of the graph, I get 15mm/20mm for the P3C and 5mm/7mm for the Trek.

That would give the Trek 5% less drag.


-- jens

Wait, no what a dumb***. The scale doesn't start from zero. It goes from 2000 to 3000, so it would be a third of that: 1.6%


-- jens

Heh heh...1.6% of 1950g is ....ta da! 31 grams. Yup...the evidence is mounting that the plots of the P3C and TTX are from Basso's runs. I'm thinking the Madone run is possibly from the same session...but probably not the Plasma.

Thanks Jens!

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http://bikeblather.blogspot.com/

1.6%? But I thought someone said "the top frames only have 0.2% difference between them?" ;)

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

You're kidding right? One guy puts a micrometer up to his computer screen and you're willing to make frame choices based on this?[code]

Aaah...but the photographic evidence revealed that the setups were NOT truly identical (different bars, right?)...maybe the difference is just the bars?? :-)

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http://bikeblather.blogspot.com/

Is this a great country, or what? :-)

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http://bikeblather.blogspot.com/

Maybe I'm doing that. Or maybe I'm going by the fact that the micrometer up to the computer screen supports a whole slew of other data that supports the same conclusion, unlike your "0.2%," which I'm pretty sure is a number you just pulled out of your ass.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Of course. That's where I get all of my numbers.

That's nothing to be ashamed of around here. :)

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

On the contrary, I think it's expected.

In all seriousness, my only point is this. Assuming that Trek didn't fudge the chart to their benefit, the only thing that this graph represents is Chris Lieto, on that day, in that particular configuration. I would venture to say that if they changed his body position, those graph lines would look very different (and their order might even change.) The same would be true if they changed the position of his water bottles, etc. And the same would certainly be true if they put a different rider on those bikes. Therefore, I don't think any of us can draw valid conclusions about how these bikes would perform for US from this data. There are simply too many other variables at play once one gets on one of the top few bikes. Once one gets to a certain level, the only way to really tell is to individually visit a wind tunnel.

 
As we've discussed, that graph probably doesn't represent Lieto. It's more likely Basso.

And yes, it's quite possible that a different rider -- particularly one who pedals with his legs at a different width -- would interact differently with the two frames. But , Ceteris Paribas (that's Economist-speak for "let's assume away everything"), I would put my money on the Trek.


- jens

Coming from a gov't economist, nice use of "ceteris paribis!" A better translation would be, "all else being equal" but you got the idea of it.

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Portside Athletics Blog

Hmm...does that mean we'll be seeing a different frame underneath Jens next season?

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http://bikeblather.blogspot.com/

I think you have hit it right on the head.

Back in March, Trek got Pezcyclingnews to write an article on the February tunnel testing with Basso on a Equinox TTX and a P3C and the difference was "within the margin of error". According to several people who were at the tunnel, it took 2 days of changing Basso's position before they could get his drag as low as on the P3C in his original position, so the TTX was only as fast as the P3C because they improved his position, not because the bikes were equally fast. According to my sources, there was a significant difference in favor of the P3C when the rider positions and the parts used were the same.

Now they show tunnel tests with the same February date, but all of a sudden the rider is Levi. Yet the CdA of Levi is supposedly the same as the CdA of Basso, and way above where Levi tested previously. Could it be that they would rather not use Basso's name anymore, and Levi was never tested on a P3C? Or do they really buy a P3C for every Disco rider to test him in the tunnel on our bikes? Or did they squeeze Levi on Basso's P3C, which would obviously be way too big for him? I can't make sense out of it.

And to top it all off, the already unsustainable "the bikes are the same" from the pez article has turned into a significant gap in favor of the TTX on bikeradar, even though they are supposedly comparing the same frames? The SSL name of the bikeradar makes no difference, that just changes the weight, the shape is the same (especially since this test is from February when there wasn't even an SSL to begin with). In the most benevolent case, it shows that tests with a rider on the bike are completely unreliable and unrepeatable (we have done tons of tests with riders on the bike, and you just cannot get riders to keep the same position when switching bikes - which is why we use a test dummy, see our latest eNews (https://customercare.cervelo.com/esupport/enews.aspx). In a less benevolent way, maybe the inaccuracy of the test was used to skew the results in favor of the one paying for the test.

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Gerard Vroomen
3T.bike
OPEN cycle

The outline on the screen method is next to useless. We did that in the past, but the line is so thick relative to the rider size that you can easily have a 1-2cm change in rider position without noticing, and that can make quite a big difference in drag. The one thing you can see with the outline is that a rider never keeps his position during a test, and therefore that it is impossible to make the sort of equipment comparisons that Trek is trying to make. It's not that the movement of the rider is a problem per se for the aerodynamics, it is that you cannot guarantee that the rider will make the same movements from one test to the next, and so that comparison is invalid. That is again why we use the test dummy, so that we can make the comparisons between equipment without having to wonder if we are really measuring equipment changes or rider changes.

And it is not even that the overall equipment changes are small, the thing is that we want to isolate changes. So we will do test where the entire bike and rider are the same, the only difference is the shape of the seattube between the front derailleur and the seatstays. We want to analyze only that part, and once we have found the best shape there, move on to the next part of the bike. You cannot do that with a rider on the bike due to accuracy, but you also cannot do that without a rider due to relevance. So the solution is to have a test dummy. We just spent another three full days at the tunnel doing just that, analyzing the bike detail by detail, one yaw angle at a time. Four hours on 10cm of tube, maybe a lot of work, but at least something that will eventually prove that we are not, as some people assume, getting to a point where all bikes are converging and the differences are getting smaller. In fact, if anything the differences seem to be getting bigger, as some bikes get dumber and dumber shapes.

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Gerard Vroomen
3T.bike
OPEN cycle

Boy, that wind tunnel seems about as leaky as a certain drug testing lab in France...

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"Go yell at an M&M"

THAT's pretty funny.

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Gerard Vroomen
3T.bike
OPEN cycle

the plot thickens. Or the soup smells fishy ... something like that ...

In grad school, I had the good fortune of getting the noted economist Jagdish Bhagwati as the professor for one of my econ courses. With his Indian accent, it sounded like he was saying "get her asparagus." It took us days to figure out what he was talking about. Great course, though, and this is coming from someone who is abysmal in economics.

It's no big deal, this sort of stuff happens all the time.

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Gerard Vroomen
3T.bike
OPEN cycle

Now, with all of the different brand and fit options available it is largely coming down to warranty and service.

This is the un-sexy part of success in this business or any business for that matter. People always love to drone on and on about product, and innovation and the science of it all ( but given what Gerard said, even that can be grossly flawed). And in the post Interbike time-frame these discusssions always seem to reach a peak. This is not to say that innovation is NOT important - it is. However, assuming that the product is close, what REALLY drives a business forward are those less glamourous and un-sexy things that you do behind the scenes with your customers to service and support them and build solid working relationships with them to the absolute best of your ability. That's hard to measure in a wind tunnel :)

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Steve Fleck @stevefleck | Blog

True enough. Elite is a good example of this. As far as appearances go, their bikes have nothing to distinguish them from the competition (IMO) and I they appear to be MOP as far as aero is concerned. Yet, they continue to build a very solid growing business, due in large part for their reputation for excellent customer service. Having an excellent bike is now table stakes for most of the market. As someone else stated earlier, it is indeed a great time to be a buyer.

Well, I would think that service always counts, whether product is similar or not. But the notion that somehow product quality and performance is converging is not yet the case in the bike industry, quite the opposite. The ultitude of possibilities has increased so much, and the degree to which new design tools are used as well, that the differences are increasing. 20 years ago, everybody bought a tubeset from one of three tube makers. The resulting frames really didn't differ that much in performance. Now, with the endless options in carbon material, lay-up, shapes combined with the intense lack of know-how in most of the industry means that the variation is much bigger in the overall spectrum. That said, it is true that within that spectrum there is a big cloud of frames that are all very similar, simply because they are made by the same manufacturer using the same materials., lay-ups and similar shapes.

We see something similar in aerodynamics. There are quite a few frames out there that are worse than an old style steel frame, thanks to bigger frontal area and stupid shapes. But there are now also (though very, very few :-) frames with less drag than the Lotus. So the size of the spectrum has actually increased.

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Gerard Vroomen
3T.bike
OPEN cycle

Of course the options for meaningless differentiation are greater than the options for significant gains. That's why you see diamond-shaped "aero" tubes and nonsense like that. But the options for significant gains now are still larger than they were 20 years ago. I agree that "significant" is still relative, the diamond-shaped frame still gets you to the finish, and if you are strong enough it may even get you there first. But any bike with two wheels will do that, and it doesn't change the fact that different equipment would get you there faster, be it 3, 5 or 10 minutes. Is that a significant gain? Depends on the person.

So basically, the spectrum in options at any point in time is greater than the spectrum in significant gains. But that spectrum of significant gains is bigger now than in the past. It may be small now (or big, depending on your own concept of what is significant) but it would have been even smaller in the past, not bigger.

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Gerard Vroomen
3T.bike
OPEN cycle

[reply]
We see something similar in aerodynamics. There are quite a few frames out there that are worse than an old style steel frame, thanks to bigger frontal area and stupid shapes. But there are now also (though very, very few :-) frames with less drag than the Lotus. So the size of the spectrum has actually increased.[/reply]

This is funny yet true. Even without optimizing tube shapes, a lot of companies could learn from the leaders in the industry...

Headtubes where the widest point is the bearing cups
3:1 aspect ratios
Bladed seatstays

It seems like everyone is always testing against the P3C.
Why is that?:)

Can Gerard tell us which are the very few frames faster than the Lotus???Thanks

Interesting. This implies that wind-tunnel testing of individuals is not that worthwhile.

We're creatures of habit: maybe a static pose will come out different. But I suspect when you get on a bike and pedal for five minutes, on average, your movements are going to be very close to identical. In my own field testing experience, I get very consistent numbers in the same position. Also, I can click my camera timer, then run and hop on the bike and get identical photos nearly every time -- and that only gives me about 15seconds. In the tunnel, the adjustments needed to match the outline were quite minimal.

BTW, does your dummy move its legs? If not, are you sure there are no interactions between moving legs and the frame? John Cobb has certainly suggested there are -- at least when it comes to water bottles.


- jens

Aren't you really comparing apples and oranges here, though? Gerard's point is that it is difficult to use the video images to be sure that the rider is in the exact same position on different bikes, fitted with different equipment. What you're talking about, though, is degree to which the rider assumes the same position each time when riding the same bike. I agree with you re. the latter assertion, at least for an experienced rider with good "body awareness", but I also know from experience just how difficult it is to set up two bikes exactly the same way, regardless of how many measurements you make, templates you devise, etc. That's partially why the P2T vs. Javelin comparison that I did worked out so nicely: the bikes essentially had the same head tube lengths and top tube lengths, such that I didn't need to change stem height or length to replicate my position, all I had to do was transfer the bars and stem together.

BTW, just for clarity, it certainly isn't the tunnel staff that leaks. In fact, they have always been super-professional, we never learn anything from them about other companies they test for.

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Gerard Vroomen
3T.bike
OPEN cycle

Thanks for all the replies to this thread.

Mostly on topic....It seems that no testing is done at 15 or 20 mph, always at 30mph. You could model the results and calcualte for slower speeds, but how do you know your perfect 30mph shape doesn't stall out at 18 or 20mph and is actually worse for your average Joe? Is it a limitation of the wind tunnel?

Testing at higher speeds increases the signal-to-noise ratio, i.e., the magnitude of the difference you're seeking to identify is larger relative to random errors in the drag measurements. There is no need to test at lower speeds, because drag force is highly linearly related to wind velocity^2 over the range of velocities a cyclist is likely to travel (and then some).

At what point is a PXC going to be faster than my old Softride RocketTT? How about a FasTT? (and yes I'm talking about a pedaling rider on board, not a test dummy, though I do believe a pedaling test dummy could be constructed using a motorized bottom bracket to turn the cranks). I love the work that you are doing and believe that Cervelo's expertise could improve upon the beam-style technology greatly, but trying to make a dual-use TT/Tri legal bike seems overly constrained due to your investment in CSC. I suspect this has played a significant role in the loss of Bjorn as a Cervelo athlete.

I wasn't a Softride fanboy until I rode one and spent some time using the adjustment mechanisms that they provide, but now I am a believer. Anyone doing a race like Hawaii on a double diamond frame is just wasting their watts. The Zipp 2001/3001, Lotus, Cat Cheetah, Corima Fox, Softride, and even the Kestrel KM40 (not the Airfoil, due to tube shapes) all bring something special to the table that just can't be replicated under UCI rules. I am not saying that every one of these bikes is faster than a P3C, but I know some of them are, and I know why. I suspect that Gerard and company know why as well, but I don't understand why they are not leading the way in pioneering a new generation of out-of-the-box triathlon bike design.

Chris

ETTX (and SSL variant, for that matter) to original TTX...relative to the bold stuff anyway.

There used to be a nice "side by side" (top and bottom, really) picture of the two right here...tried calling it up last night and the pix weren't there anymore. Odd, since one of them was mine. Maybe you can resurrect?

Carl

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Carl Matson

Funny, I noticed the same thing about the KM40 vs. the Airfoil. I'd only ever seen a KM40 until Interbike, and I was suprised that the downtube of the Airfoil Pro seems to be much worse with some hard angles and a relatively wide "flat spot" running down the middle. Wonder if they sacrificed aero for stiffness...

Have you tested your Softride vs. a P3C? Just curious to hear what you found. I'd also like to see someone resurrect a Zipp frame and test that, as they certainly seem to be better executed beam bikes than the Softrides in terms of aerodynamics.

the CAT Cheetah, I've heard, is also one of those bikes that people love to love, but that doesn't actually do as well as people think. The only "test" I've ever seen is the TOUR velodrome test, which I don't put much stock in. Lotus, no doubt. Corima's wheels are nothing special in terms of aero, and I've never see any data on the Fox, so I don't know. A lot of these are the bikes that people believe must be fast. But I'm not sure how many (except the Zipp & Lotus, where I've heard confirmed numbers) actually are really special.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

And you know this how?

These:

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

yes...those exact red X's.


weird...that it would happen to me on both my home and work computers. were it one or the other the explanation would be easier. I'm assuming everyone else can see those as actual pix...?


Carl

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Carl Matson

Thanks for the response. What I am gettting at is: Let's say at 30mph you have your rider and and your smoke gun and you see perfect airflow from their shoulders down to their butt. If you then slow down to 18mph and the airflow is the same, I agree with your linear relationship. But if at 18mph the airflow breaks off mid way down the riders back, wouldn't that negate the linear relationship?

Except, were air to break off the riders back at one speed and not the other, it would happen at 30mph, not 18mph. Really, though, the Reynolds numbers of the flows are within the same regime. People have this idea that 20mph and 30mph are totally different worlds. Physically, they are not. 300mph and 30mph are very different. But 30mph vs. 20mph, the flow is basically identical. And any increased turbulence (which would cause separation) would occur at the higher speeds, not slower.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Thanks for helping me through my mental block. ;)

"People have this idea that 20mph and 30mph are totally different worlds."

Nothing like a little myopia, eh?

Because I've tested every one of the bikes I mentioned except the Cat Cheetah and Lotus on the same track under the same conditions with the same (and different) position/wheels/aerobars/etc. The numbers are obviously only good for me and are dependent upon my body, flexibility, riding style, etc. I have held and measured a Cheetah though, and it's every bit as well designed as the Fox in most parts, and better in several.

The order of performance has been:

1. Zipp 2001 (this was/is not mine unfortunately)
2. Softride Rocket TT w/ custom internal cable routing and fairing to fill the poorly executed area in front of the rear-brake and some work around the beam joint. A Bonty speedbottle works really well there.
3. Corima Fox - I had to do a lot of work to get this to fit me reasonably well. It was really too small for my leg length although the TT length was fine. Had to build a custom seatpost to acheive proper seat height and angle.
4. Kestrel KM40 (despite it's lower level of aero performance, this is a fast and comfortable bike that I prefer to ride most of the time)
5. Aegis Trident

Some of the ordering on the lower end (3, 4, 5 changes with different wheelsets. The KM-40 specifically does better than the other two with Nimble Crosswinds).

Now obviously I am not working with Trek or Cervelo's funding and I have constrained myself to bicycles that use 650c wheels, but I suspect there aren't more than two or three non-professional fitters/aerodynamics folks out there who spend more time testing than I do. I am working with minimal wattage that doesn't seem to improve that much with training, so the application of my brain is all I've got.

Chris

On the track, as in 0° yaw?

I have never seen an independent test that shows any of those bikes to be faster than a P3C, and certainly none of our internal tests do (and we don't really have a reason to fudge our internal tests, but of course that you can't verify that). As for pedaling, it has a very small effect, simply because the velocity of the foot is only around 10% of the air velocity. The velocity of the rest of the leg is even less. It certainly would be possible, though quite difficult, to make an articulated mannequin. and it would likely affect the aerodynamic similarities because those joints then need to be covered, etc, etc.

And you do realize that when people test a live rider with pedaling legs, he is not actually pedaling at normal speeds, so it's not the ultimate either. But when the whole bike industry does tests without riders or nonsensical tests with riders that can't repeat their position accurately, I am pretty happy that we develop a method that is over10x more accurate than the live rider method.

As an example for UCI-illegal bikes that don't benefit from this, if I take a KM40, I can improve the aerodynamics by adding a well designed seattube (we have actually done stuff like that, just for fun). Bottomline, the downtube can aide the flow off the front wheel (though not many do), the seattube can aide the flow over the rear wheel (again not many do), the toptube is great structurally without much drag (and taking it out requires the downtube to be larger), removing the seatstays sounds nice until you see how big the chainstays have to become to take the load. There really aren't very many things that make sense to do differently if you toss out the rules. And certainly nobody will make a non-UCI legal bike that is more aero than a UCI-legal Cervelo, simply because the potential gains aren't there. And frankly, because we can afford to spend much more effort on research than anybody else, simply because triathlon is a much more important market for us than for the other companies. And we can do that on a legal or illegal bike, that makes no difference. CSC is certainly not holding us back from making an illegal bike, I wouldn't know why.

I hope this explains our reasoning a little bit, gotta get back to work now.

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Gerard Vroomen
3T.bike
OPEN cycle

But your assertion was that one or more of these bikes is more aerodynamic than a P3C, yet you apparently haven't tested the latter. So again I ask: how do you know that the P3C isn't the fastest of all?

BTW, I wouldn't describe the Fox as "well designed", as it is common knowledge that it performs very poorly from an aerodynamic perspective...

Felt testing put the Lotus, Zipp, and Felt DA all ahead of the P3C. I don't recall all of the details, but at the very least those 3 were mentioned. We've been down this road before and dug up the relevant posts by SuperDave etc.

I haven't tested any 700c bicycles because I don't have any 700c aero wheels, and because there aren't any of those bicycles around here to borrow unfortunately. I am hoping to test a P2 eventually, but my attempts to purchase one have so far been unsuccessful.

Anyway, just to put my money where my mouth is (one is bigger/more plentiful than the other, but whaddaya gonna do?), I will happily transport myself and my Softride to the SD LSWT and pay for my own tunnel time during a "Cervelo Week" if they will provide a P3C for me to compare to.

Chris

They've re-worked the front end a bit... wider fork baldes, fork crown is much different, and the downtube comes closer tothe front wheel.

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*
The Dude abides.

But of the three bikes you just listed (Felt, Lotus, Zipp), only two were on your original list, and then you added a bunch of bikes that don't have anywhere near the credibility of the two that were (Zipp, Lotus). And, both the Lotus and Zipp are not-UCI legal, but for entirely different reasons, basically negating the idea that there is a common UCI-illegal design that is faster. The Felt DA is UCI-legal, and so is the Walser, and both of those are also at the top of the heap. So of the maybe five fastest bikes - Zipp, Lotus, Felt, Walser, Cervelo - three of the five are UCI-legal. Add in the Trek, which got this whole thread started, and you have four of the six. So where is the compulsion to design a UCI-illegal frame?

And, to Dr. Coggan's point, you've not tested a P3C (or even a P3), yet both of those bikes ARE readily available in 650c sizes (though not your size?).

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

I appreciate the time it took for you to reply and the information contained therein. The fact that you have not had any illegal frame test faster than a P3C during internal tests sounds interesting, but I remain skeptical given that you've not listed what has actually been tested.

If you can tell me that you've tested Lotus, Big Mig's hour record Pinarello, Ulle/Riis Pinarello from 1997 TDF, GT Superbike I & II, Obree's Old Faithful (frame, not the position), BMC TT01, Softride FASTT, Carbonsports Total Eclipse, then I am inclined to believe you. I don't think that is a claim you can make, and despite the amount of time, energy, and money you've put into the SD LSWT to develop your bikes, I believe your research applied to some alternative tube schemes would result in something truly impressive.

I am willing to be wrong, so tell me I am.

Chris

http://forum.slowtwitch.com/...post=1516581#1516581

:-)

BTW, in the independent testing conducted for Project 96, the Lotus finished dead-last among the aero bikes, whereas IIRC the Hooker (which in my hands is slower than the P3C) bested the Zipp 2001. Now there very well could be some reasons other than just random error for this reshuffling, but my point is that I don't think you can necessarily rely on cross "study" comparisons that don't even include all of the bikes in question to draw really firm conclusions.

[OT]....Not sure who the gov't economist is, but it's neither ceteris paribas, nor ceteris paribis...I like asparagus which comes closest

I don't see that they need to bother testing those - the carbonsports looks like a brick wall with a bike behind it - the HT is so wide and the cable stops are mounted on the side. The Pinas were chunky too, the Sword always looked like a bad copy of the Zipp - if Pina had been able to make a good bike before the rules changed then I'd expect them to have something good once the restrictions came in. As Gerard has said before - what evidence is there to suggest that a company that can't make a fast legal bike will be able to make a faster illegal one. Rather like the weight limit - everyone can make make a bike that is under it but not everyone can make a bike that is under 6.8 and safe/durable/nice riding.

No, I can't score a P3C or Felt 650c in my size, since I have a 36.5" inseam. P2 classic and P3 alu are both options, but given that Cervelo asserts that the P2C is faster than the P3 alu, I didn't think it was worth bothering with that one. I am still intending to put a P2 classic through it's paces vs. the Softride.

I am in no way asserting that Cervelo isn't doing their homework or working tirelessly to create some beautifully aero bikes. I also don't believe the TTX design is faster (though maybe in the same range) they are clearly both using a lot of FEA and CFD as well as tunnel time to develop the bikes. What I don't like is discounting entire designs based on poor implementations of a core idea (like removing tubes). With the advances in carbon over the past 10 years, certainly a narrower, better shaped softride/zipp could be constructed using the expertise of Cervelo's engineers.

Chris

No, I test on a 3/8 mile auto race track. Very windy most of the day, but calm in the morning. I test with wind direction/speed, temp, humidity, etc all being recorded at 5 second intervals on my laptop. It's good to have an in with the physics department where I went to high school.

Chris

Except, and I'll agree with Gerard here just on aero principles - a well designed seattube should be more aerodynamic than having a the leading edge be your wheel. You have much more control over the shape, and it isn't moving, and tire choice won't make any difference. So I don't see that a beam bike actually is (or even should be) better.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

I am still intending to put a P2 classic through it's paces vs. the Softride.

Just a note that Endurosport in Toronto still has a limited selection of classic Cervelo P2 frames( all 650c wheel size) in stock that can be built up ala cart with any gruppo you want. This is the frame/bike that first put Cervelo on the map. Call 416.449.0432 and ask to speak to Dan or Peter for more details.

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Steve Fleck @stevefleck | Blog

That is who I have been trying to get one from for ages. It just doesn't seem to happen. You gave me the tip originally, so thanks for that.

Chris

When did I say that my theoretical improved design wouldn't include a rear wheel fairing?

In point of fact, it does (currently made out of shaped foam glued to a piece of aluminum that is screwed into my lower bottle cage mount.

It's the space above the wheel but below the rider that I tend to dislike, mostly because I have a 37" saddle height and there is a LOT of space there for me.

When my fairing is actually finished and usable, I will post a picture.

Chris

How come it does not happen?

I know they have them in stock - not sure on sizes and what size you need.

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Steve Fleck @stevefleck | Blog

The two bikes you mentioned that Cervelo could improve Zipp/Softride were both seattube-less bikes, so I drew what seemed to the logical conclusion from that.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

So at yaw angles close to zero.


How are you measuring power?

The orientation of the track I test on is approximately perpendicular to the wind coming off of the bay in Eureka, Ca. Variation seems to be only about 10 degrees during the summer afternoons at this location. It's an oval track, so the bike/rider/wheels will see pretty much every yaw angle possible. That is why I feel like this type of testing, while not being accurate down to a single watt, will always be more useful as a real-world test than a tunnel.

I originally started with an SRM Amateur system and then moved up to an SRM Pro.

Chris

Well, the major flaw that I've always seen in these designs (since I was a little kid in fact) was that the air separates after the down tube and then must be broken again by the wheel with all of downfalls that you mentioned. Filling the gap so that air is only broken by the down tube and then remains attached all the way along the rear wheel gives you the advantages of both worlds.

When I say "improve", I mean find the flaws and fix them. That's what engineers do.

Chris

Sorry, I thought you were testing first thing in the morning, when there was very little, if any, wind.


Okay, next question then: how do you process the data, and how reproducible are the measurements?

Spot the engineer!

??

I'm not an engineer.

Following that logic to the extreme results in a bike like that built by Brent Trimble, which as it turned out wasn't particularly aero, at least with a rider aboard.

Really? I assumed that you were based on the advice you've been giving people and the questions you were asking!

Sorry 'bout that.

No need to apologize - I've been called worse. ;-)

That's right...he could have called you a physician .

Tom (the REAL engineer)

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http://bikeblather.blogspot.com/

Now that I might have taken as an insult. ;-)

well i can see my selve as indepent testing

and evrytime i did the testing the cervelo was faster timetrail bike then TTX
(altough i like TTX cycling wise better)

as i also have some test from giant time trail bike as well the CFD of those bike's

and the amount of work cervelo put in their bikes of aerdynamic testing is not for nothing

again hats of for that

i only would like to see that they where more open in the CFD testing
like other compagnys do example is here GIANT

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http://www.ada.prorider.org
skype ceesbeers191053

Cees,

Are you referring to the new Giant TT bike? It seems to be a step back from the new age TT-bike thought.




Never had I considered non-uci bike as obsolete as after this thread. Very eye opening.

I test at many different times of the day and collect immense amounts of data. Temperature, humidity, wind direction, wind severity, etc all at 5 second intervals. I typically make a run at least 10 laps of the 3/8 mile track, but it really depends on how small the changes I am expecting are going to be. If I am trying to resolve < 5 watts, I would probably do 20 laps. I use a pressure sensor for starting and logging times for each 1/2 lap top make sure that gusting winds are not adversely effecting lap times and ruining my resolution.

I work as a software engineer for a design of experiments and automated experimentation company, so I work with several custom tools built off of our product line to store and analyze correlated time-series data. Our company is not in any way related to the bike industry or really this kind of data collection, but since I work specifically on the import/export of our designs and response data, it's easy for me to build custom modules for my data input devices.

I work with people who are experts in numerical analysis and general statistics/mathematics/optimization and have tapped their collective talents in my pursuit of bicycle speed. I assure you that the attention to detail and repeatability of my data makes Tour Magazine's aero testing look like it was arranged by Fisher Price engineers.

Not trying to put anyone down, but this stuff is very important to me and I take it very seriously when someone publishes data that says system a is faster than system b.

There are about 2 hours a day during which I can collect reproducible data (2-3 watts) for "tough" wind conditions (when normalized based on wind angle and velocity), and about 2 pre-dawn hours when I can collect calm condition data (usually < 2 watts)

Chris

That almost looks like a geometry prototype. It's neither the Trinity Alliance nor the Trinity Carbon. Wonder if it's a one off built to test a specific geometry (or for the specific needs of a given rider)?

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Man, you guys are still talking about this? ; )

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Shawn
TORRE Consulting Services, LLC
http://www.TORREcs.com

That almost looks like a geometry prototype. It's neither the Trinity Alliance nor the Trinity Carbon. Wonder if it's a one off built to test a specific geometry (or for the specific needs of a given rider)?[/reply]

It was for rogers - they had a video clip about it during the tour. You're right on with the geometry proto theory.

It was for rogers - they had a video clip about it during the tour. You're right on with the geometry proto theory.[/reply] YES! I am SOOOOOOOOO badass... ;)

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Rapp, any chance you'll expand on your initial thought in the BTR insiders?

I could simplify it a bit:
TTX: 32mm downtube width
P3C: 28mm downtube width

Interesting to note Cees comments that he tested the P3C as being faster than the TTX, but found the TTX to be nicer to ride. The TTX is a very stiff bike (a bit heavy with the aluminum crown fork, but I see they've changed that for the SSL) and rides very nicely. The cable routing is also excellent and nicer than the P3C with the behind-the-stem entry and full length cabling for very nice shifts.

I've certainly been very happy with it. I'm not sure I would say it is the most aerodynamic frame you can buy, but I also don't think it's gonna hold anyone back. And there are lots of other things that make it very nice. One big thing that I'm very happy with is the seatpost binder. Everyone likes how clean the Cervelo binder is (the TTX is, aerodynamically, also very nice), but I don't think they are the most secure based on people I've ridden with. Now, is a seatpost binder worth X watts? I don't know. I'm just saying that I think Cees point that there are certain things that make a bike nice besides aerodynamics.

But I know that aero also sells. It's too bad that Trek wasn't less marketing on this. It would have been fine to give the whole story - Basso, P3C, position changes, etc. Shows that the frames are close enough, shows the importance of positioning. But I guess that's why I don't work in marketing.

I've been happy with my Trek. As I said on BTR, I don't know that it's the fastest frameset in the world. But it's certainly done me right this season, except for wanting to go off course ;) I'd not have any trouble highly recommending it to someone looking for a TT bike.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

I didn't realize the Trek was 32mm wide. Thanks for the info.

There was also a comment on a BTR thread on this same graph. Someone stated that when Trek tested the bikes sans rider the Cervelo tested faster. The BTR member contacted someone from Trek and response was they believed the cleaner front end of the Trek(fok fin to downtube, cable routing) was the difference maker with the rider on board and that the better rear end of the Cervelo(seatpost shape, wheel coverage) didn't have the same effect. Take this as what it is though, second/third hand info. This theory also goes against Gerard's belief that a bike tests very similarly with and without a rider that he has expressed before on the forum.

The TTX 9.9 might be faster than a P3C but given their scarcity and unavailability it really doesn't matter now does it? Why bother with a fancy test on something you don't actually sell - what I mean by this is a shortage on supply of frames.

Trek: Our bike is crazy fast and aero, look at the pro's who ride it! Very distinguished athletes ride our bike the TTX. However, we are really sorry to tell you this but you can't have one b/c we don't actually have any ourselves to sell you, especially not the venerable 9.9 SSL (wait til spring 08 at least). Further, you have to visit a Trek LBS to acquire, don't trip on the tricycles or big wheels while you spend $8000.

Cervelo: Our bike is crazy fast and aero, look at the pro's who ride it. Very distinguished athletes ride our bike the P3c and p2c. Say, you want one? Got to your LBS and pick it up today, heck, have 5 or 10 or 12.

There is a part of the story that wasn't covered...availability ; )

Hence, I am getting carpal tunnel syndrome trying to find a used one on the net.

"Say, you want one? Got to your LBS and pick it up today, heck, have 5 or 10 or 12"

So they are at stores? Seems everyone is having a tough time finding a P2c or a P3c....

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"Lemond is cycling's version of Rev Jessie Jackson." -johnnyperu 5/18/07
"Just because I suck doesn't mean my bike has to" -rickn 9/2/08

Does this thread mean I screwed up by buying a Kalibur??? Well thanks a lot Norm! Now I'll never keep up with that damn pink Planet X bike!

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________________________________________________________________________
It's not how many years you have left in life, it's how much life you have left in your years!

do the bikes race?

no, a human must make them move.

if human a/trek and human b/cervelo P3C race, who will win?

the stronger/well trained rider NOT the faster bike!!!

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Retul Certified Fitter. gebioMized Pressure Mapping http://www.PedPowerPerformLab.com.
Retailer of Wahoo Fitness, Sable Water Optics, Enve Composit, Giro and more.
Zone3 USA Ambassador - use code DEAN25 for 25% off
http://www.OasisOne-Twelve.com - The ultimate hands free hydration system.
https://www.athlinks.com/athletes/19354499 - results.

Keep that NON-sense to yourself please,,,,,,,,,,lol

I HAVE ONE.....................na na, na na na..........!!

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http://theworldthroumyeyes.tumblr.com/

You know, I can't help but notice the number of bike companies, fairly prominent ones at that, that benchmark the P3C as the defacto standard for aerodynamics.

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Tom Demerly
The Tri Shop.com

Blame yourself, the dealers and consumers created the benchmark.

I'm not sure why bikes like the Lotus or Superbike aren't used, they are the benchmark.

Isn't the softride & Zipp reported faster than any double diamond frame? Why doesn't the public, the dealers and industry as a whole use them?

-SD

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https://www.kickstarter.com/...bike-for-the-new-era

Isn't the softride & Zipp reported faster than any double diamond frame? Why doesn't the public, the dealers and industry as a whole use them?

Wouldn't the simple answer be UCI legality?

.

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Bob C.

The "science" on any matter can never be settled until every possible variable is taken into account.

Ah yes, well that is certainly what drives the marketing: the UCI professionals aboard them.

Afterall, no one got excited about Obree's bike.

Given the P3c's palmares under Dave Z. and Fabian the past few years, it is an easy (and commercially marketed and attainable) target/benchmark.


-SD

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https://www.kickstarter.com/...bike-for-the-new-era

People that know would and should use the Lotus or Superbike as a benchmark. People that want to sell stuff wouldn't. They need to feed the consumerism driven by having the fastest stuff readily available and most easily seen in the hands of a pro, not necessarily the fastest stuff that ever existed.

...I get it, that's why we have to drag so many bikes to the wind tunnel for testing. It isn't enough to have a SBII, SBIII, Hooker, Hotta, Lotus, we also need to bring the canadian, french, and aussie track frames...

-SD

I know you do and I applaud your team for trying to create the fastest bikes ever, not just the fastest double diamond. It's cool to see a company be so active in creating a product that they can engineer to the level that a marketer can sell. That's no easy feat!

We've got way more enginerds than people in marketing, that's for sure...

-SD

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https://www.kickstarter.com/...bike-for-the-new-era

Dave, I would trade my TTX for a DA.............just thought I'd make that comment.................

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http://theworldthroumyeyes.tumblr.com/

Shouldn't that be the Lotus, SBII/Canadian, SBI/Hooker, French (LOOK), and Aussie/French (Corima) track frames? ;-) (Not sure where a Hotta might fall.)

EDIT: Of course, a glaring omission from this list is the BCF track frame...

I think you've got your SBs switched, the SBIII I was referring to is this one:

It is indeed fast, but not UCI legal, and not SBII fast.


-SD

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https://www.kickstarter.com/...bike-for-the-new-era

Not so much switched, as I just skipped over that iteration (which I'd forgotten). Anyway, I've edited my post to reflect what I meant...thanks for helping me set the record straight (assuming, of course, that my memory/guesses are in fact correct).

No luck getting one BCF riding Scot to bring his to Ft. Collins last month, otherwise we'd have the full deck, although I understand the special fork turned out not so special once a non-disc wheel was installed up front.

I can't confirm your ranking, I always assume you know more than me anyway...

-SD

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https://www.kickstarter.com/...bike-for-the-new-era

That is a totally valid question. Trek is probably responsible for selling a lot of P3C's with their latest round of "tests".

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Tom Demerly
The Tri Shop.com

Interesting, and consistent with what John Cobb has said about aero seatposts (at least if you think about it).


If I do, it's only because I've been collecting such numbers like lint for quite some time...

Speaking of Trek, what happened to Damon?

I think he's around here occasionally.

Happy Holidays to you Sir.

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Tom Demerly
The Tri Shop.com

BTW, did y'all experiment with a comparable ultra-narrow fork? Extrapolating from John's seat post findings, I'm starting to wonder if perhaps a disk front wheel might indeed be faster if paired with such a fork.

AC,

I think you'll forgive me if there was a decision to not make a front disc specific fork.

In general:

narrow spaced fork + disc wheel = good
narrow spaced fork + any molded spoked (iO, Hed3, Corima) wheel = very bad
narrow spaced fork + spoked wheel = not so good

wide fork spacing + disc wheel = nearly as good
wide fork spacing + any molded spoked (iO, Hed3, Corima) wheel = not so bad
wide fork spacing + spoked wheel = good

In the interest of making something commercially viable, the latter choice saw development...we did bring the Oval fork along to see if it helped with the molded wheel performace.

-SD

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https://www.kickstarter.com/...bike-for-the-new-era

Katsanis says as much in The use of CFD in the chase of Olympic Gold, although it seems as though they focused more on just the interaction with a disc wheel. The UKSI forks look like this



The question I've wanted to try and answer though, is whether a thin monoblade fork (eg. if you just cut off one of the legs) would be faster with a composite spoked wheel, and if so how thick would the monoblade have to be before you lost the benefit

Xav

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AeroCoach UK
http://www.aero-coach.co.uk

In the case of the UCI bikes it doesn't matter, you can't use monoblade forks.

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https://www.kickstarter.com/...bike-for-the-new-era

Ah, but I don't do UCI events :)

Xav

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AeroCoach UK
http://www.aero-coach.co.uk

So now we're back a few posts up, the industry (dealers, consumers, manufacturers) is not interested in making fast non-UCI legal bikes.

But as an hypothetical question?

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AeroCoach UK
http://www.aero-coach.co.uk

At $15/minute I'll put the question on someone else's budget!

Hypothetically, I'd say having a 1 sided fork would be about a 50% improvement with a molded wheel's spoke pulse/interference drag than a 2 sided fork.

Given those results, you're forgiven. ;-) Thanks so much for sharing them!

That sounds like a fascinating read - is there a place that a schlub like me might be able to lay their hands on a copy? (EDIT: perhaps this is the cyclingnews article that was the source of the pic?)


I hadn't seen that pic, and it's literally worth a thousand words...thanks!

[reply]So now we're back a few posts up, the industry (dealers, consumers, manufacturers) is not interested in making fast non-UCI legal bikes.[/reply]

Does any bike manufacturer make a realy aerodynamic bike that is NOT UCI Legal?


.

Um... I find just the opposite. And yes, the 9.9 SSL is not available yet because it is a 2008 model. Trek has '07s on closeout right now because they have too many.

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*
The Dude abides.

I also vaguely remember the P3C (and every Cervelo for that matter, hell for that matter every high end product of any kind) having availability problems at first and/or being released behind schedule.

The TTX 9.9 SSL might be behind because Sram Red are the components and those are pretty hard to come by right now.

[reply]Isn't the softride & Zipp reported faster than any double diamond frame? Why doesn't the public, the dealers and industry as a whole use them? [/reply]

Because they look like tampons on wheels? :)

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--
"Rock and roll, dude." -- Dave Z., on winning TTs in all 3 Grand Tours.

Cheers - I think I'll have to do my own neanderthal testing then, cue lots of broken bones ... :)

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AeroCoach UK
http://www.aero-coach.co.uk

Sorry, I was being needlessly elliptical, here we are, I also got the original author wrong but it's Katsanis' work that he was quoting:

http://www.fluent.co.jp/...mpic-Sport-Paper.pdf

Xav

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AeroCoach UK
http://www.aero-coach.co.uk

IIRC, ultimately it's been found that because of the additional strength, you need substantially more material than for a dual-bladed fork. So much so, that the aerodynamic savings were actually less. The dual-blade design is very sound structurally. I don't think the monoblade is really going to help you, until more substantial material improvements come along.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Totally - if you look at the example of the Burrows monoblades they are much deeper and also thicker than normal, depends to what extent the fork blade interference is having an effect I suppose. The other problem is the hub/fork interface, you need a much wider diameter axle than normal and therefore a modded wheel, which may or may not be worth it! You could fudge it with a quick release and a spacer on the missing fork side to press against but it would be very dangerously flexy

Xav

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AeroCoach UK
http://www.aero-coach.co.uk

Just because the seat tube is curved doesn't mean it acts as the same frontal area as the wheel. There is interaction between the tire and the tube itself and of course the tube has to be at least 25mm wide, (I think its around 28mm on the bike you mentioned) whereas the wheel can be 19mm.

I'm not suggesting that one frame is faster than the other, but overcoming missing frame members on double diamond aerodynamics is very difficult, and mirroring the shape of a wheel doesn't make the frame member dissappear aerodynamically.

-SD

Doesn't a straight leading edge on a tube have less surface area than a curved tube?

What happens to the wheel/tube interface?


-SD

It does, but frontal area and surface area are not the same thing. Think about the surface area of an airplane wing - very large - but the frontal area is quite low. By curving the seatpost, you will increase the surface area, but you won't necessarily increase frontal area.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Agreed,

In this application, what do you think is better, surface area or frontal area?

-SD

frontal area is much more dominant for aerodynamics. An increase in surface area is not inherently bad at all. Consider this bike, which you may have heard of:

Here, the additional surface area is on the sides. I.e., this has more surface area on the sides due to filling back to the seattube. So I wouldn't be too concerned with surface area, since we all know how this bike tests. I actually think the DA has more surface area on the seattube from backfilling to the wheel with a straight leading edge than the P3C does from curving the seattube. The frontal area in each case is basically equivalent. The question is which offers better aerodynamics. I suspect you know the answer. But in both cases, you have two bikes that choose an increase in surface area to achieve superior aerodynamics. Either design is going to test better than a simple airfoil shape that does not fair the rear wheel at all.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

I have nothing to add except that the seat tube width on that bike you've pictured is only 25.5mm wide.


Otherwise, can I have the publication rights to your comments? :)


-SD

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https://www.kickstarter.com/...bike-for-the-new-era

Exactly. the 25.5mm width is a big part of why the frontal area is so minimal, which is also part of why the bike is fast. So again, it's about frontal area, not surface area.

Yes, you can have them. :)

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

that thing looks looks like a fat pig with those wide base bars, wide ass cranks, ugly brakes....

deep in it's heart it wants to look like this:






g

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greg
www.wattagetraining.com

Does Greg ever descend as well?

[reply]frontal area is much more dominant for aerodynamics. An increase in surface area is not inherently bad at all. [/reply]

Bigger frontal area tends to result in pressure drag due to separation, surface area results in surface drag. While pressure drag is around 10x worse than surface drag, it's still an issue.

That's funny...

Gregclimbs is a bit of a misnomer and a joke all at once. I climb like a brick and descend like one as well...

G

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greg
www.wattagetraining.com

A great deal of bikes are desgined, or should I say styled, to look fast. Anyone with any kind of aerodynamic knowledge can spot the bikes designed by an industrial designer, as opposed to an engineer with knowledge of aerodynamics. The geometries are far from "clean" with styling features that quite frankly disturb the airflow and increase the drag rather than reduce it. If you look at an F1 car, where downforce is the main driver behind aerodynamic design, not drag, there are many external aerodynamic devices with a great deal of complex interactions between them and the rest of the car. I feel many, not all, bike manufacturers style their bikes with F1 cars in mind with the idea that it must look fast or revolutionary to sell. There are detailed interactions between the various parts of the bike and rider but at the end of the day a clean bike is a fast bike.

Some manufacturers make all kinds of exhorbitant claims about how much time they spent in the wind tunnel and on CFD analsysis . They'll publish "non-partisan" comparisons against other bikes where miraculously their bike ends up being the fastest. This has become a marketing battle without quality engineering to back it up. As a racer, with a degree in aeronautical engineering , over 15 years of experience in aerodynamics ,including wind tunnel testing and CFD, this devalues the work that some bike companies truely put in. I'm not a bike company employee with any particular affiliation, but if you look at the bikes each one produces you can tell which companies genuinely use the engineering tools they claim and those who just market themselves as using them. Wind tunnel testing and CFD is expensive, a stylized design and some marketing spin is a lot cheaper.

By your highly trained eye, what bike frames do you consider to be the fastest aero wise??

Your top 5 list would be nice :-)

Shane D

This is probably the most accurate post on this subject I have ever read and I definetly agree.




One of my favorite modern examples was the new Pinarello design shown in the UK's cycling weekly. When asked if it had been taken to the tunnel they replied 'that they didn't need to as they obtained the aero design knowledge off their previous designs'. the cycling reporter stated in his appraisal that ' going by their previous results they're obviously right in this policy'. With this king of of ignorance, it's no wonder we have half the dross on the market we do.

Shane,

Hey, I thought my comments would be dismissed as the rantings of an engineering snob. You know I thought about this and I cant come up with 5 current production frames (from different manufacturers)where I think knowledgeable aerodynamic design was actually employed in the up front design process (as opposed to after the fact benchmarks and the like). The fact that I only genuinely believe one manufacturers claims (aside from the work the University of Sheffield did on the British Cycling track bike) regarding the level of engineering in their products would also make me appear bias.

Cheers

With your aerodynamic experience, can you perhaps explain the double standard of Trek's when it comes to LeMond and their Aeolus wheels? They claim the 'trip strip' on the forks of LeMond tri bikes reduces overall drag by reducing surface contact with the air and virtually creating a larger airfoil shape. When comparing their wheels to Zipp, however, the 'larger airfoil' then becomes a 'low pressure wake' on the trailing edge of the rim (out in front of the bike) and increases aero drag. So...err...which way is it?

And can you at least affirm (and thereby commit ST heresy) that proper rider positioning on even the most aerodynamically deaf and dumb --well, not the MOST, but one that's poor...say, a tri on a Cannondale SystemSix-- is going to be more beneficial than riding on the sleekest bike with an aerodynamically useless position?

Very interesting bike set up you have there.

Looks like you took the minimalist approach with no basebar and no pedals.

I ride with a guy who races with only one aerobar extension. He is an interesting character.

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Team Endurance Nation

Interesting, yes. That, and they both probably share the same destiny of crashing...Badly.

Wow, you make a lot of assumptions (about me, my abilities, the bike's difficulty in turning without a basebar, etc.)

The reality is, I rode this position/setup for a whole season of racing and training before committing to it (search my old posts for more info on my "hot swap" setup.

I had one close call last year on a training ride where a car cut me off (left turn in front of me) that the setup worked fine and the outcome wouldn't have been any different with full bars - I avoided the car.

G

p.s. The lack of pedals was due to needing another pair of x1s as they are narrower than the stainless versions.

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greg
www.wattagetraining.com

If my personal hero, Natasha, can crash, then I don't believe anyone else is immune. She is a total bad ass.

Where are your hands when starting from a standstill and need to pull on the bars? I've seen some UK TTers use this approach but am having a hard time imagining how you get underway.

Yeah, you are right. If you don't look down the road, you will hit shit.

Doesn't mean it was the bar setup's fault. Doesn't mean that I or anyone else has a "destiny to crash".

:)

G

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greg
www.wattagetraining.com

Starts are a lot like braking, choke up on the bars (hands inside the brake levers) and support forearms on the armrests.

It does require using appropriate gearing (no starting in the 54x11), but that is a good thing.

G

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greg
www.wattagetraining.com

What... no bento box? Just kidding... that is on SICK ride. This is, like, the third time I have found myself LUSTING after a bike you've posted. We must be drinking from the same koolaid since you keep buying my dream rides. The difference is that I dream about them while you're riding them.

A couple of quick questions: Are those Blackwells or old school (ie non-dimpled) 808s? Just wondering about your choice in wheelsets. Why no disc? Also, you seem to have your saddle adjusted pretty far back. Are you riding slack?

Also... can you post a pic of the drive side. Just for curiosity's sake.

Well, God speed to you and keep the rubber side down.

Powertap

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36 kona qualifiers 2006-'23 - 3 Kona Podiums - 4 OA IM AG wins - 5 IM AG wins - 18 70.3 AG wins
I ka nana no a 'ike -- by observing, one learns | Kulia i ka nu'u -- strive for excellence
Garmin Glycogen Use App | Garmin Fat Use App

actually, they are dimpled 808s (pt2.4 rear)


'cause that wheel also has a wheelbuilder disc cover (almost, but not quite as fast as the sub9). actually, the wheels, powermeter, crankset aren't really "sorted" yet.. that is just current running trim. Obviously the 808+cover won't work @ masters nats.

I have the fsa cronos on there now as the low q-factor. If the quarq comes out anytime soon, I will test it on these cranks and run a sub9. if not, I might try going back to my vista integrated crankset (which kills the crank based powermeter) and forces the 808 rear (or a replacement with the 1098!), but there is an overlap issue with the crank and the thick bb shell.

if I don't like the quarq, the SRM goes back on with sub9.

maybe with custom crankarms that match the narrow fsa crank...


yup. I am not a triathlete and so my saddle position matches my road bike. I have no reason to ride steep as 1) I am flexible enough to hold the position and 2) there is no discernable drop in power despite the "closed" hip angle that the slack+LOW position creates.

I attribute that to years of specificity and trining/racing in essentially the same position for a long time.

g

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greg
www.wattagetraining.com

Do you route the powertap wire internally, or does it go down the downtube? (or is it wireless?)
enjoy,
tom

As mentioned above a pt2.4 (wireless).

Whatever solution I ground out on will be wireless - pt, quarq or srm...

As probably the slc-sl will be eventually as well so the cabling doesn't bugger up aerodynamics.

G

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greg
www.wattagetraining.com

Ah, sorry, missed that. I saw the rear brake cable down by the bottom bracket and thought that was an internally routed PT cable. Nonetheless, nice bike! :)
tom

Why no basebars?

Why not? :-)

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http://bikeblather.blogspot.com/

Is that the popular thing now? What do you do at the beginning when you are trying to accelerate and reach maximum speed? What about if you need to get our of the saddle to get up a hill? What about accelerating out of a corner? Seems like it would be hard without the basebar. Does one gain much aero wise without one?

See Greg's descriptions above about how he uses them.

...and the answer to your last question is "Yes."

(BTW, there IS a base bar on his setup...it's just really small ;-)

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http://bikeblather.blogspot.com/

Definitely a "different" setup. Not sure what to make of it.

 
See the "what aerobars do you use" thread for a full description.

I used the best individual parts I could find to make it :)

Actually, I did that on the whole bike...perhaps a new thread is in order.

G

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greg
www.wattagetraining.com

Hey!...shouldn't you be getting on an airplane or something? :-)

Have a safe trip!

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http://bikeblather.blogspot.com/