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.
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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.
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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.