well, i rode around the block today with a disk cover and felt roughly 34.204 percent faster then yesterday. hope this helps.

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___________________________________________________
Team Medique Powered by Silber Investments

Not so much, but I am glad that you had a nice ride.

Stephen J

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I believe my local reality has been violated.
____________________________________________
Happiness = Results / (Expectations)^2

Some disk wheels are faster that others. Not all disk wheels are created equal. Some disks are well just disks. Others actually were engineered to be as aero as possible. You will never get a consensus on which is best.

But based on the information I have seen, ZIPP 808 in the front with a ZIPP disk in the rear is the best. Too bad because I would really would have loved to get a set of Campagnolo Bora wheels because I think they are the coolest wheels out there.

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________________________________________________

Pasadena Tri Club

Well if you look at the Hed website, which has drag numbers for all of their wheels, it is pretty clear that the disk is superior to their Stinger 90 which is the closest thing to a 100 or 808 that head makes.

I've heard the claims that the BR 200 is faster than a disk, but only as a "Someone told me that they heard that Cobb had told somebody that the 200 wheel is faster than a disk under certain conditions..." not exactly from the horses mouth.

The last published numbers that I saw showed that the new Xentis wheels were becoming very slippery and were getting very close to a 999 set, but were still out gunned as the yaw angles increased.

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This is your life, and it's ending one minute at a time. - Fight Club
Industry Brat.

Real disc, not covers, are generally still the fastest in certain wind conditions. Disc wheel speed comes from reduced watts more than an aero advantage when comparing them to other wheels like our 100 or the 808. At "0" yaw a flat disc on the back of bike is practically invisible to the wind, but the solid surface area keeps the air flowing and smoothes it out so that you do not have spoke interruption, which requires more watts, to move down the road. As a rider gets into different crosswind conditions in a Triathlon, the aero effect comes to play and a shaped disc will have a couple of points in yaw that in theory would make it faster. There is not an accurate way to measure if the increased side load on the tires offsets the aero gain but the watts to spin the wheel stays consistantly lower than other wheel combinations. Wheels like a 100 or our 200 may offer equal aero dynamic performance over most situations but a disc will always set a lower drag number at some point over a range of "0" - "30" yaw. Marketing people tend to show just the lowest drag but I think there are more important things to look at. Rider confidance in bike handling is a big deal as is weight for acceleration. Wheels are like golf clubs, there are certain ones that work best in certain conditions which includes rider performance level and skill.

Whoa-when God speaks I listen!

John, John, John! Come on buddy stop with the information here. You are not supposed to tell us what you think is best with the given information you have. Your supposed to sell Blackwell stuff. Here is what you should have said.

"Blackwell technology is so advanced that even defense contractors won't touch it. Balckwell is about giving you the up most in cutting edge performance. If you don't use Blackwell you will be a whole hour slower in your next triathlon. Use Blackwell!"

See we don't want "information" we want huge promises and stickers.

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customerjon @gmail.com is where information happens.

So with covers, I hope that I am speculating correctly, that there are large differences in drag as a result of differences in the transition between the cover, and the rim; and the closer you have the transition to 'seemless' the better the numbers (closer to a real disc)?

Stephen J

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I believe my local reality has been violated.
____________________________________________
Happiness = Results / (Expectations)^2

This is an interesting post with lots of good information. In the end though it would be really nice if someone (an expert) would just concede that there is very little difference in any of the similar wheels (size, shape) from each manufacturer. For example, I have a hard time understanding why *everyone* says a Zipp 808 is faster than a Hed 90 Stinger, or Blackwell 100. Same thing for a disc versus a 80/90/100 rear wheel. In the end how much time are we really talking about, and does it really matter to triathletes? Of course this forum is littered with roadies who time trial, have no interest in running or swimming and I suspect fuel much of this debate. In the end though isn't all of this analysis just pointless for almost every triathlete? Aren't all of these wheels really, really close to each other? Does any wheel really hold a clear cut advantage over any other at this time?

a lot of closely shaped/sized wheels are very close in performance... but if you are buying new, wouldn't you want to spend money wisely?

if close enough is good enough for you, great. the rest of us will sweat the details.

g

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greg
www.wattagetraining.com

My opinion is that when comparing "race wheels" to "race wheels" no matter the manufactuer you are talking seconds over the course of an Ironman, whereas "training wheels" to "race wheels" is minutes.

"a lot of closely shaped/sized wheels are very close in performance... but if you are buying new, wouldn't you want to spend money wisely? "

This is my main point. Spending money wisely usually (for most) involve spending twice as much on wheel x as wheel y in order to save a handul of seconds over an IM. That just doesn't make sense to me.

"if close enough is good enough for you, great. the rest of us will sweat the details."

That's cool. You sweat the details. I am going to use that time to train more. Time will tell who benefits the most :).

I completely agree.

you ASSumed that I was trading training time for "sweating details" time...

and make sure to let us know when you loose that race by those few seconds if you feel you made the right choice.

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greg
www.wattagetraining.com

aero tests have shown that wheel covers can offer similar aerodynamics to disc wheels... although the wheel may often be heavier than a disc. on a flat to rolling course- weight is negligible... check out www.analyticcycling.com/ to see impact of weight... lenticular wheels are more aero or equal to flat shaped discs- so a lens shaped wheel (like Mavic Comete/HED/Bontager) will be faster in greater Yaw angles than a flat wheel- such as (Zipp, et al) At lower Yaw angles (less wind and/or a slower rider)- they are basically equal. So - you could get a $65 wheel cover and put it on a $200 rear wheel and be faster or equal to a $1500 flat disc...

I have never missed a spot by a few seconds, but I have gained two in the last few years. All in the final 100 yards or so of the run. Maybe you're right. Maybe I should worry about a few seconds over a long day....

my emphasis added. depends on the weight difference. and the course, and .... there are seconds to be had via weight (again sweating the details).

well, if we are talking IM distances, the difference increase.. most savings are typically calculated for the typical road TT of 40k. if you have followed any of this, then you know the differences are bigger @ IM distances as the time on course (your "long day") amplify the magnitude of difference. same thing for a slower rider - the benefits increase due to more time to make savings.

again, it is a cost/benefit analysis. if you like investing your time into training (and are participating to race and thus potentially win) and you prefer to leave 15s/40km (or a whole minute @ IM distance) on the table for you competitors, good on ya.

I prefer to treat my equipment selection like my training: methodical, calculated, precise and purposeful.

g

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greg
www.wattagetraining.com

[reply]. There is not an accurate way to measure if the increased side load on the tires offsets the aero gain but the watts to spin the wheel stays consistantly lower than other wheel combinations. .[/reply]


mmm
i just do not know how you are measuring ??!!!
,but we do this ,and hence its a part of calc in our spreadsheet ,this in combination with the dynamic pressure

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

Thats why I am getting a RENN Kaiser!

STOP THE MADNESS! JUST BUY THE CAMPY DISC AND A BORA FRONT!

Truth be told, if you've got the money to burn, go buy the best you can. If you don't do some research but don't overburden yourself on it because in the end the training is what will pay off the most.

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In a former life, Hellriegel was my training partner. Going head to head all day, I let him win at Kona in 1997.

John,
Could you please expand on this a little, i.e. the part about the covers? The only tunnel data I've seen is that a cover is, at least, no worse than a flat disc aerodynamically...and if the main advantage of the disc is lack of spoke windage, as you infer, doesn't a cover do that? Thanks.

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http://bikeblather.blogspot.com/

"Real disc, not covers, are generally still the fastest in certain wind conditions"

Crapola John. I'm calling you out on this one.

In a previous post a long time ago you claimed that a disc is just a disc and if a cover is sealed properly along the outer diameter than it works just as well as any other disc. I'm sure you've read Kraig Willet's test. Also, some authorities have claimed that lenticular is faster than flat. Covers are lenticular.

Josh from Zipp used the arguement that they couldn't duplicate the same effeciency with a disc cover and box rim as with their dedicated disc because of turbalance formed with the rim where the box rim met the cover. However, a custom cut disc from wheelbuilder.com on any aero rim would eliminate this problem.

When I used my cut down CH Aero cover with a 60mm Hed Jet I even went to the extreme of using black electric tape around the diameter of the disc to ensure a sealed fit.

So give us one legitimate reason why a cover would not be as fast as any other disc.

Sorry for the delay, work got in the way :(. Any ways, my point is simply that I don't believe there is any measurable difference between any of the really good wheels (this would be Zipp and Hed). I am sure the marketing department for all the wheel company's will disagree, but that is my feeling. I've ridden just about every Zipp and Hed combo and just can't see any discernible difference between any of them. They are all good, and all fast. So to conclude; this is a pointless debate that can't really be proven to any degree of certainty. I just don't believe anyone has ever lost a *race* because they chose wheel x over wheel y.

"So give us one legitimate reason why a cover would not be as fast as any other disc."

How many disc covers does Blackwell sell in a year? What is the price of the Zipp disc they sell versus a $60.00 cover? Same as any company. What "we" sell is the best and that's what you should be racing attitude. That's why I think this debate is crap.

There's no doubt that John and Josh are in the business of selling expensive discs, but i wouldn't go so far as to question their integrity.

I think John's concern with a disc cover would likely be that it must form a tight seal at the outer diameter with the rim otherwise aerodynamics is compromised. However, if this is done, how can it not possibly function like any other disc?

There are minor factors such as weigh and dimples that may add up to a second or two gain. This is important to a pro TT'er looking for that last micro advantage, but to a MOP middle aged AG'er such as myself, the real world gain or the coolness factor is not worth the extra $$$$.

I am not questioning anyones integrity, but I do think we need to see the data if such thoughts are to be believed. Seem fair?

No they're not. Lenticular means having a lens shape (i.e. double convex), and in a cross-section a lens has curved sides. Covers are instead cone shaped, with straight sides in a cross-section.

There's a lot of heresay for sure. Hed publishes their data on their website and Zipp gives a good aero explanation on theirs. That German magazine has published their test results. The only test published involving a disc vs cover that I'm aware of is Kraig Willet's.

I'd really like to see more info on frame aerodynamics. If there is any area that needs to come out in the open more it's there.

"Covers are instead cone shaped"

My bad. Thanks for the correction.

OK, here's one reason.. At "0" yaw. a flat disc will have less frontal area than a spoked wheel that has been covered. more frontal area is slower. You are correct that I have said that a disc is a disc and I still generally go by that but, in a hair splitting contest like this, then the covered wheels aren't quite as good, it can be because of ridges where the spokes are, gaps at the hubs or seams that are not quite right. For the money, covers offer a great performance increase, I just don't personally think they are as cool.

Finally we have an honest and to the point ending to this madness...

As with most AG's bikes... it's all about the coolness factor and not how fast I can go..

I ride a zipp disc and it's cool;-)

No cover will ever sound like a disc either!
Rickeh

The data out there making people favor their Xentis wheels was produced by Triathlon magazine in Germany. They did indoor velodrome testing showing that a pair of xentis MK1 on a P3 using an SRM was 3 watts faster than an 404, the next year they went back and did the same test using lots of different wheels. That year the Vuelta Carbon Pro (old 404 rim but with 12 spokes) won the test at -38 watts from baseline with Xentis at -37 watts, 808 at -36 watts and 999 at -29 watts, interestingly the Corima disc/3 spoke came in at -22 watts, Lightweight -27 watts with the Ritchey Carbon (404 rim) and Easton Carbon (404) rim being -28 and -29 watts respectively.

The problem with these tests is that they were done at zero yaw. The press in Germany really treated this as a breakthrough, claiming that discs are actually slower than spoked wheels or composite spoked wheels. The problem is that nobody took into consideration that the test was done on an indoor velodrome. This concept is something we've been trying with no success to sell to the US track program, that at 0-2 or 3 degrees of yaw, the skin friction of the disc makes for higher drag than a good aero wheel, but past 2-3 degrees of yaw, the disc dominates most anything. If you look at the Tour magazine data or any of the zipp published data, you see that this is not some revelation, but exactly what the data has been predicting for years, and for road and tri use this is a non-issue as 0 degree or near 0 degree wind angle is so unbelievably improbable, even on an indoor track a shorter or higher banked track will induce larger effective crosswind angles due to rider lean and stirring of the air by other riders and so on, but in this case they were testing at a rather large/shallow indoor track and actually managed to replicate almost exactly a lot of the low yaw wind tunnel data we have taken over the years. The problem of course is that this was published in a triathlon magazine and not a track racing magazine...

If you look at the Tour magazine data from 2005, you see this predicted almost exactly, they are showing the 808 and xentis both having slightly lower drag than the disc at zero yaw with the xentis ever so slightly winning, but get to 5 degrees and it is not contest anymore and at 10 degree the difference between the disc/808 which are almost identical and the xentis is about 80 grams of drag or roughly 10-11 watts additional to maintain the same speed.

Bottom line is that some creative rim shaping makes a wheel like the 808 faster than a dis at around 0-4 degrees of yaw and again at 8-12 degrees of yaw (as verified in both Zipp and Tour mag data within grams of each other) but past that, the disc kills everything. Cees is right that there is some increase in tire rolling resistance due to increased side loading, but the side loading of the disc at say 20 degrees is about 3800 grams which is considered minor compared to the 40000 grams of vertical load the tire would see with an 80kg bike rider system with 50/50 weight distribution, although nobody has a good way of measuring this, however, at say 20 grams of drag a disc has more than a 100 gram drag advantage over any other wheel, so it would take a lot of RR to offset the gains.

As for covers, the BikeTechReview data has been discussed by a lot of people I know in the industry and there are a few things to be aware of, first the disc used was borrowed from somebody, it is a 1992-1992 Zipp 19mm wide disc with 20mm braking zone that was ground parallel, this is an old technology that was replaced years ago as the lip between the body and brake surface causes considerable drag...construction similar to this is still used by quite a few manufacturers, but is really not ideal. Also, the tire on the wheel was quite used and not the same tire used in the other testing, and was from my understanding rather used as this wheel belonged to somebody. As a result, the data for the real disc is far worse than anything anybody else from Tour magazine to us to John Cobb has ever recreated for even a similar disc much less a modern one, so in that way I think the comparison between the two wheels is a bit misleading in that particular test. Also, the disc cover wheel used was a very meticulously constructed and maintained wheel with very nicely sealed edges and no apparent blend problems between rim and skin. This test does show that a cover can make for a very efficient wheel, but having said that, there are two issues people always overlook with covers. First, a cover is not lenticular, it is conical, not that is affects the data too much, but the conical wheel tends to have both more surface area and more frontal area than a lens or flat disc, so at lower yaw angles the performance suffers. At higher angles the wheel performance is entirely dependant on the care taken in assembly, as I said with the original Zipp disc construction and the construction of most clincher and even some modern tuby discs, a 0.030" (0.75mm) step at the skin/rim interface will cost you 6 watts or possibly more. So while a cover can be made quite fast my experience is that almost all of the ones I see in IM pits and such are not constructed or maintainted to their potential. As someone who used to use and manufacture covers before I worked for Zipp I can tell you that I used to spend hours before every event tweaking and maintaining the thing to get it just right, the best is to permanently silicone bead the one half to the rim using C clamps and wood blocks to get the surfaces exactly flush...the other side really should have a valve hole cut in it and do the same for it's asembly as taking the thing on/off can really throw the alignment out and create discontinuous surfaces, I had a coach that drilled all of this into us as juniors without any data, but I can now say after having spent hundreds of hours in the wind tunnel that he was spot on.

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http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc

"I just don't personally think they are as cool. "

Now the real reason!!

I can't certainly argue with that point, your wheels are cool. But wouldn't it be cool to see somebody at the local tri on an old bianchi 12 speed with a disc cover smoke the field. Saw a woman win her AG this way one time. Now that was really cool.

Performance wise there is little doubt a disc is a disc is a disc. And that includes covers. We're grasping for straws mentioning the things you did.

"So while a cover can be made quite fast my experience is that almost all of the ones I see in IM pits and such are not constructed or maintainted to their potential."

I brought those points up in my previous posts. If it isn't fitted correctly then maximum aero advantage is lost. I'm not an engineer but that's just common sense. I was always quite meticulous when fitting mine.

BTW, although I've been a staunch defender of covers and like to keep you industry guys honest about this, I actually owned a "real" disc as well for my P2K. An older 650c Spengle (later became Xentis) that I paid $100. for on ebay.

"My opinion is that when comparing "race wheels" to "race wheels" no matter the manufactuer you are talking seconds over the course of an Ironman, whereas "training wheels" to "race wheels" is minutes."
- - Precisely. I could spend the megabucks for the Zedtech 999 w/ceramic bearings and shave 90 seconds off my IM time, but that still won't fix my problem, because it's under the hood - just not enough horsepower coming from the engine room.

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Cousin Elwood - Team Over-the-hill Racing
Brought to you by the good folks at Metamucil and Geritol...

"there is very little difference in any of the similar wheels (size, shape) from each manufacturer."
- - Very true. Christopher Kautz talked me out of dumping my old HED Cx in favor of an H3, because he said I'd gain 8-10 seconds over 40K. I've never been beaten by 8-10 seconds.

"Same thing for a disc versus a 80/90/100 rear wheel."
- - Big error there. The primary advantage of a disc is the reduced egg-beater turbulance from spokes passing the seat and chain stays. No way a spoked wheel can get close.

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Cousin Elwood - Team Over-the-hill Racing
Brought to you by the good folks at Metamucil and Geritol...

so, in your opinion, is my rear 808 faster with or without a cover in rolling terrain and moderate wind conditions??

"- - Big error there. The primary advantage of a disc is the reduced egg-beater turbulance from spokes passing the seat and chain stays. No way a spoked wheel can get close. "

I generally agree with this statement, but if you look at the drag numbers provided by Hed you will see that their Stinger 90 is very close to a disc until about 12 degrees when the 90 starts to go up and the disc continues to go down. Like I said, I generally agree with the the idea that a disc is the fastest rear wheel, and I always seemed fastest when running a Zipp disc in the rear with an 808 up front. Than t being said, I am just not convinced any more of a significant difference between a 90 rear and a disc rear. I can see 5-10 seconds per 40k, but not much more. I guess it all depends on the wind- right?

Hey tjs
Well I have been on a Spinergy Rev-X (very fast) a Renn 575, and I sold that wheel this season to get an American Classic 420 with a Powertap SL hub with a wheel cover. and I can’t tell difference between the Renn and my 420 with the wheel cover. It’s it a custom cut one from wheelbuilder.com.
But having the wheel cover and the power meter is the best, Hands down!
If you want to go faster I feel very strongly that is the way to go.
Dan…

Well well well I think we all can agree. Aero wheels are faster than no aero wheels. All the disks are pretty fast, disc covers are fast, but maybe not so cool. Pretty much a 50mm or trispoke front is pretty fast, a deeper one may be faster under some circumstances but maybe harder to handle. A deeper rear is about as good as a disc in a lot of situations.
WE CAN SPLIT HAIRS TILL THE COWS COME HOME, AND IT DON'T MEAN SQUAT.

Buy your wheels from John, Steve, Cees or Josh and you will go faster than you are going on no aero wheels. Buying a bunch of them probably will not make you go any faster. Do we have to argue this for the next ten years on a daily basis.? Enough already.

I think it is sort of rude to be"Calling someone out on that one" especially since we know Josh, John, Cees, and Steve have spent hundreds of hours in the tunnel and we have spent little if any. Yes we all have our bias as do they, but all the aero wheels are gooing to make you faster than none and if you reach around and scratch your butt a couple times one wheel may end being slower than another. And I think if you read carefully what the experts say it is very hard to get a picture of a wheel in all the possible real world conditions in the tunnel.

One of my favorite antidotes is how fast was my HED deepdish wheels when I got off a TT in the rain and there was probably a quart of water in each rim? Does the yaw angle factor in there. At the time they were supposed to be the fastest wheels in the world.

I don't see where we disagree, and I am not sure what the purpose of your post was in reply to me. I didn't call anyone out so I am a bit lost. That being said, I think a cool thing would be for one of the wheel makers to come out with some sort of test data that doesn't claim their stuff is *always* the fastest. When was the last time you saw this? Everyone claims their stuff is the fastest and that is a bit, well, misleading, or at best incomplete to say the least. It's about time folks are held accountable for their claims. If your going to say is x is faster than y then you should eb able to prove it- or not say anything. I don't see this as unreasonable.

My only point is this; I don't think there is any real difference between any of the wheels out there. That being said, I do think my 999 set was the fastest I have ever owned. It may or may not be faster than anything else, but I always had my best results on them.

BTW- how did you get a quart of water in your wheels? That sounds a bit odd. Are we talking the Jets or something?

Let me guess... You didn't major in business or marketing?

"if you look at the drag numbers provided by Hed you will see that their Stinger 90 is very close to a disc until about 12 degrees when the 90 starts to go up and the disc continues to go down."
- - I'm not an engineer, nor do I play one on TV, but I believe the numbers HED is giving are for aero drag only, not rotational drag (caused by egg-beater). Having upgraded a few years ago from a HED Deep (90mm ~Stinger) to a disc, the disc yielded >90 seconds faster over 40K, based on real world trials at seven races in one season. Also, top speed on all races showed a higher number (downhilling +40mph). That's anecdotal, but there was a clear and significant improvement at every race.

"Than t being said, I am just not convinced any more of a significant difference between a 90 rear and a disc rear. I can see 5-10 seconds per 40k, but not much more. I guess it all depends on the wind- right?"
- - I do find the disc a bigger advantage on a windy day, because I don't have the wind-related handling issues of the guys riding 404s, 808s or some such equal f-r setup. Having the disc on the back really minimizes the wind push on the front wheel (I run a Cx, which is similar to a 404, maybe a tad deeper). For 5-10 seconds, I wouldn't have bothered to buy the disc, although I do think it has cool factor. If it was only 5-10 seconds faster, I'd be hard pressed to identify any difference. 5-10 seconds could easily just be me having a bad day or a few extra morons who ride to the left and bollix my pacing when I need to pass them without getting killed.

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Cousin Elwood - Team Over-the-hill Racing
Brought to you by the good folks at Metamucil and Geritol...

well i have 404's (tubs) and i inquired at my bike shop about getting a rear disk cover on my 404 as i run a powertap sl. well the owner of the shop suggested i just stick with my 404's without the cover as we said my wheels where already aero and the covers don't sit flush and may cause more drag. But he did say if i just had regular wheels that yeah i should buy the rear disk cover.

my 2 cents.

although now i wish i would have bought the 808's

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Like T says, "Remember it is all about the Bike because it is all about the Run!"

RENN KAISER BABY!

For coolness then it has to be Campagnolo Bora wheels. Zipps are too common.

So what do you want? To be cool and ride Boras and be a little slower? Or ride Zipps which are not as cool but are faster?

Coolness rating:

Campagnolo Bora
Easton
Zipp
HED
All others

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________________________________________________

Pasadena Tri Club

Nope- when I went to college I wanted an education :). As for now I prefer to make an honest living. I do work in business though so go figure...

I sold my 404's two summers ago to buy a 808 front to go with a Zipp disc I had. I never road faster than when I had my 404's. After owning all of the Zipp and most of the Hed wheels I can honestly say that the 404's were my all time favorites. Don't know why. I really wish I would have kept them. Do yourself a favor and hang onto yours. There is nothing to be gained by switching to other wheels.

Its been a while since I've been to physics class but there seems to be a lot of misuse of the concept of watts on this message board.

If it takes less watts to move a wheel through space there are only two things that I can think of that could have happened
1. its more aerodynamic - the force of wind impeding its movement is less.
2. there is a lower rolling resistance.

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Erik
Strava

thanks a lot i appreciate that. I will hang on to my 404's. i got them on the advice of a guy who is a Kona Qualifier year after year. He is much faster than me, he is sponsored and he rides 404's he said they are his favorite wheels, although he rides the Z4's!!!

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Like T says, "Remember it is all about the Bike because it is all about the Run!"

it worked on me! i ran out and bought BR disc and 50 front!!! thanks, john

Amen to that. The only other thing I would add is bearing friction, but otherwise I agree 100%

Or you can just put the things on with electrical tape. It works just fine.

I leave it to you guys to ponder why I go to most races with an 808 that has CH Aero covers taped on, and leave the Zipp clincher disk and the Carbonsports Lightweight disk at home.


-- jens

Why doesn't a well fitted cover make that disk sound?

this thread seems to have died over the weekend but some questions remain. Alvarov asked an interesting question and a couple of weeks ago I asked about the relative aero performance of various clinchers disks but didn't get any manufacturer replies.

Last week I asked pretty much the same question of Zipp via their tech. inquiry service on the website but have not received a reply to date.

I suppose it is for the versitility depending on the conditions (although I know of very few conditions that would warrant not having a disk, uless it is not allowed; in which case you would not bring it); so now that I think about it, I have no idea why you would do that. Now you have me curious. Why would you not take a disk rear wheel when you have two discs at your disposal????? The ONLY reason that I can come up with in the past two minutes of thinking about it is that it packs easier in the bike case...is this right?

Personally I have a rear zipp 280 rim with ultralight aircraft covering epoxied to the rim and hub flange adapters (which I constructed) which functions as my full time disc. With the rim/ sapim x-ray spokes, hexhead nipples (for truing from the spoke hole) and american classic hubs, it made a lighter disk than was available at the time, at about 1/10th the cost (I got a deal on the pieces).

Stephen J

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I believe my local reality has been violated.
____________________________________________
Happiness = Results / (Expectations)^2

There are a couple of reasons: 1) The 808 has a powertap hub (I've taken the SRM off so I can use various funky cranksets 2) The 808 with covers is faster.

In 0 yaw field tests, the disks all come out pretty close. On real world courses with winds, the 808 with the disk covers has beaten the others every single time. Don't know why that is, because it looks goofy. But it it has been pretty consistent. Most recently, I rode a 54:18 40K with only 252 watts. And that's with my less aero position.


--jens

54:18 40K with 252 watts?

Wow! Man you are one "slippery" dude :)

Any reason you don't go with an even deeper front wheel (i.e. Blackwell 100 or PX 101)? I'm sure you can handle the winds easily.

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____________________________________
Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD

thats pretty interesting...

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

The BW100 demands a pretty narrow tire, i.e. 20c or better yet, 19c. I don't know, but I would guess the PX is similar. Most of the TTs around here are on roads that are a little too rough for that.


-jens

Ah Ha! I have a theory...Maybe, a spoked wheel gives you a wheel with very CLOSE aerodynamics to a disc, but the real world Crr is lower (given the 'suspension effect' that a spoked wheel gives); as I noticed that you said the 808 was FASTER, not MORE AERO. Another possibility is that since you are riding with power meter with the 808, you are able to ride more efficiently than with the other wheels, thus making you faster as well (I forgot about the power meter in my last post).

Stephen J

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I believe my local reality has been violated.
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Happiness = Results / (Expectations)^2

interesting theory ... I wonder what the road surface on Jens' skunkworks testing facility is like?

Most wind tunnel data is fundamentally flawed. Wind, because it lacks
the density of other substances, is frequently controlled by extrinsic
factors. A riders movement, for instance disrupts wind, as does low
hanging trees, the refraction of the sun's raise, and (it's now
indisputable after years of debate), the tides. Obviously, less wind
resistance will equal faster bike times because, despite the chaotic
nature of wind, over a long course the laws of probability all but
guarantee the chaos will balance into some semblance of normalcy. The
problem is, in wind tunnel testing, the controlled circumstances often
eliminate a lot of these normalizing factors, so select extrinsic
factors have the potential to control a test's outcome (for instance a
high tide).

As a result, I've been working with pro teams in a hydro tunnel.
water flows past riders and the frames in the same manner as wind but
its greater density gives it higher consistency and more reliable test
data. Our hydro tests are race proven and have yielded some
surprising results. First, Zipp wheels, at anything over 5 degrees of
yaw, drop resistance at all times except in direct sunlight, at high
noon, when the Pacific is at its lowest monthly tide. In most typical
morning race starts, when tides are most often high and the sun's rays
are less direct, Easton wheels present the optimum race conditions.
Most participants can expect to save 5-10% on their bike leg.

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team website: http://snappletriteam.com/

team blog: http://snappletriteam.com/?page_id=10

How do you correct for all the scuba gear on the riders? When we were testing various horses for water polo I can tell you the scuba gear was a major problem...

Wait!

How are you extrapolating water resistance results to determine what time of day air will flow past the bike best? How would the tides affect the localized wind resistance presented to a bike?

Is this a clever joke? haha

ok..yes that a joke...lol

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

The most difficult aspect of working with professional riders in the hydro tunnel was getting the comfortable with the process. There were doubts as to the validity of the process, but as I think I made clear in my earlier post our results cannot be disputed.

This isn't meant to be rude so please don't misinterpet but your question regarding scuba gear shows a clear lack of understanding of the process and how a hydrotunnel really works. Also, I think horses and water polo sounds like some sort of attempt at levity and I am trying to engage in serious scientific research into what we will make us all faster and it would be appreciated if we could all stay on the straight and narrow in this thread.

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team website: http://snappletriteam.com/

team blog: http://snappletriteam.com/?page_id=10

"First, Zipp wheels, at anything over 5 degrees of
yaw, drop resistance at all times except in direct sunlight, at high
noon, when the Pacific is at its lowest monthly tide. In most typical
morning race starts, when tides are most often high and the sun's rays
are less direct, Easton wheels present the optimum race conditions.
Most participants can expect to save 5-10% on their bike leg."

This is why I always ride my Zipp wheels while holding a carbon dimpled umbrella.

I can see that this group needs a lot of educating.

We do not need to input controls regarding the time of day into the hydrotunnel in order for it to yield reliable results. Wind is the just the flow of air and it is influenced by a number of factors -- some of which I discussed above. Wind levels will change from day to day and from place to place, but those levels (and this is the important part) are impacted by a number of different factors. These factors do not exist in a vaccuum -- hence differing wind speeds from differing directions.

The problem with wind tunnel testing is that manufactured wind is moving at static levels in static directions. As we all know from experience on the bike, the wind never flows at a constant speed in a constant direction. I may be more in tune with the wind than others given my vast experience, but even a wind that feels steady from a directional point will have minor shifts in its heading.

The hydrotunnel takes all of these factors into account and generates results that are reflective of real world riding. Riding in a tunnel with a 30mph wind in your face has nothing to do with what we will see out on the course.

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team website: http://snappletriteam.com/

team blog: http://snappletriteam.com/?page_id=10

you haven't even mentioned relativistic effects. Clearly a major source of error ....

And the earth's surface doesn't even present an inertial reference system so even Newton would be displeased.

You know the rules around here, it there are no pictures, it did not happened.

I was hoping to avoid dropping names, but here's Lance celebrating 7 consecutive TdF victories:



Here's Lance in the Hydro Tunnel:





Let me know what more is needed.

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team website: http://snappletriteam.com/

team blog: http://snappletriteam.com/?page_id=10

....mother of god

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

The hydro data makes sense, but why didn't Lance ride Eastons?

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http://snappletriteam.com/

So it just sprays water as well as wind at the biker?

Why is lance naked?

How does spraying water on the rider somehow make for collecting better data about riding when it isn't raining?

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter