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Slowtwitch Forums: Triathlon Forum:
Trek TTX is Faster Than the P3C

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Rappstar

Oct 10, 07 11:07

Post #51 of 236 (3167 views)

Re: Trek TTX is Faster Than the P3C [jens] [In reply to]	Can't Post

In Reply To

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?).
--------------------------------------------------------------

Do you remember this photo:

Note the yellow drag history that the rocket scientists at Pezcyclingnews neglected to blur out. Way back when I pixel counted that to determine that Basso's drag was, in fact, .254. I think I posted the calcs here and on weightweenies somewhere at the time.

-- jens

Well Basso is the obvious choice anyway, as he'd definitely have numbers for a P3C and for a TTX. Duh... Only question is, were they from different tunnel runs? If so, that would seem to neglect *some* of the credibility...

Rappstar

Oct 10, 07 11:08

Post #52 of 236 (3161 views)

Re: Trek TTX is Faster Than the P3C [zebragonzo] [In reply to]	Can't Post

In Reply To

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!

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

Tom A.

Oct 10, 07 11:09

Post #53 of 236 (3156 views)

Re: Trek TTX is Faster Than the P3C [Rappstar] [In reply to]	Can't Post

In Reply To

The stats are not for the TTX, but rather the new TTX SSL.

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

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.

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?

Carl

Oct 10, 07 11:38

Post #54 of 236 (3120 views)

Re: Trek TTX is Faster Than the P3C [Tom A.] [In reply to]	Can't Post

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
(yeah, I work at Trek...it's not a crime)

MuffinTop

Oct 10, 07 11:53

Post #55 of 236 (3101 views)

Re: Trek TTX is Faster Than the P3C [Tom A.] [In reply to]	Can't Post

In Reply To

I'm thinking the comparison may actually have been from Basso (who would've had a P3C to compare to, right?).

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.
--
"Oh no, it's the dreaded Muffin Top!" --Mythbusters
http://willronco.com

c.dan.jog

Oct 10, 07 12:01

Post #56 of 236 (3089 views)

Re: Trek TTX is Faster Than the P3C [MuffinTop] [In reply to]	Can't Post

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

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!"
www.fleetfeetchicago.com

www.wmds-unleashed.com

Rappstar

Oct 10, 07 12:10

Post #57 of 236 (3074 views)

Re: Trek TTX is Faster Than the P3C [Carl] [In reply to]	Can't Post

In Reply To

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?

Andrew Coggan

Oct 10, 07 12:17

Post #58 of 236 (3066 views)

Re: Trek TTX is Faster Than the P3C [Rappstar] [In reply to]	Can't Post

In Reply To

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.

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.)

jens

Oct 10, 07 12:48

Post #59 of 236 (3031 views)

Re: Trek TTX is Faster Than the P3C [Andrew Coggan] [In reply to]	Can't Post

In Reply To

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

(This post was edited by jens on Oct 10, 07 12:50)

Andrew Coggan

Oct 10, 07 13:11

Post #60 of 236 (3011 views)

Re: Trek TTX is Faster Than the P3C [jens] [In reply to]	Can't Post

In Reply To

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.

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

In Reply To

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

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.

(This post was edited by Andrew Coggan on Oct 10, 07 13:14)

Tom A.

Oct 10, 07 13:23

Post #61 of 236 (2986 views)

Re: Trek TTX is Faster Than the P3C [jens] [In reply to]	Can't Post

In Reply To

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...

Tom A.

Oct 10, 07 13:36

Post #62 of 236 (2963 views)

Re: Trek TTX is Faster Than the P3C [jens] [In reply to]	Can't Post

In Reply To

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? :-)

rmur

Oct 10, 07 14:34

Post #63 of 236 (2916 views)

Re: Trek TTX is Faster Than the P3C [Tom A.] [In reply to]	Can't Post

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?
--------------------
rmur

jens

Oct 10, 07 14:53

Post #64 of 236 (2899 views)

Re: Trek TTX is Faster Than the P3C [Tom A.] [In reply to]	Can't Post

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

jens

Oct 10, 07 14:56

Post #65 of 236 (2897 views)

Re: Trek TTX is Faster Than the P3C [jens] [In reply to]	Can't Post

In Reply To

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

Tom A.

Oct 10, 07 15:22

Post #66 of 236 (2874 views)

Re: Trek TTX is Faster Than the P3C [jens] [In reply to]	Can't Post

In Reply To

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!

Rappstar

Oct 10, 07 16:17

Post #67 of 236 (2848 views)

Re: Trek TTX is Faster Than the P3C [Tom A.] [In reply to]	Can't Post

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

Large

Oct 10, 07 16:36

Post #68 of 236 (2829 views)

Re: Trek TTX is Faster Than the P3C [Rappstar] [In reply to]	Can't Post

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]

Tom A.

Oct 10, 07 16:42

Post #69 of 236 (2820 views)

Re: Trek TTX is Faster Than the P3C [Rappstar] [In reply to]	Can't Post

In Reply To

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

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

Tom A.

Oct 10, 07 16:42

Post #70 of 236 (2818 views)

Re: Trek TTX is Faster Than the P3C [Large] [In reply to]	Can't Post

In Reply To

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]

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

Rappstar

Oct 10, 07 16:43

Post #71 of 236 (2818 views)

Re: Trek TTX is Faster Than the P3C [Large] [In reply to]	Can't Post

In Reply To

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]

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.

Large

Oct 10, 07 17:09

Post #72 of 236 (2794 views)

Re: Trek TTX is Faster Than the P3C [Rappstar] [In reply to]	Can't Post

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

Rappstar

Oct 10, 07 18:12

Post #73 of 236 (2756 views)

Re: Trek TTX is Faster Than the P3C [Large] [In reply to]	Can't Post

In Reply To

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

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

Large

Oct 10, 07 18:19

Post #74 of 236 (2750 views)

Re: Trek TTX is Faster Than the P3C [Rappstar] [In reply to]	Can't Post

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.

jens

Oct 10, 07 19:43

Post #75 of 236 (2707 views)

Re: Trek TTX is Faster Than the P3C [Large] [In reply to]	Can't Post

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

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