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Aerodynamic wheels(13 posts)

Aerodynamic wheelsSilas_Greenback
Aug 20, 2002 7:02 AM
I can't imagine that this is the first time anyone has asked the question, but here goes. Do aerodynamic wheels, say like the Mavic Ksyriums, provide enough extra speed to justify the cost? Obviously, for the pros, they make sense, because that is how they earn a living and they don't have to pay for their equipment. I can see their utility in time trials, but for other racing you would have to be going pretty fast to make a difference and drafting is free and more effective. Or is this another example of the Tiger Woods golf club syndrome: buy his clubs and you will play like him. That is the theme of most equipment advertisements, and I wonder if aero wheels are another example of the same flawed logic. The weight difference is not that substantial versus conventional 32 double butted spoke wheels, and the advantage, if any, must lie in the allegedly faster speed from reduced wind turbulence. Or something like that.
re: Aerodynamic wheelsstr8dum1
Aug 20, 2002 7:41 AM
K's are not aero. You are right, riding in a pack nulls aero benefits. Most racers use a deep carbon rims. That way they are actually aero (>38mm deep) and are lighter than non aero box section Al rims.

For good multi purpose wheels, open pro rims with DA hubs are fine. people like flash, thats why K's sell soo well. anyone with 1/2 a brain could build a set of wheels lighter and much cheaper than Ks that are easier to true and have off the self parts.

You know what kind of rider you are, sit in a do no work or aggro off the front break style. If you like to go off teh frnt, go with a deeper carbon rim. Hell just go with a deep carbon rim anyhow.
re: Aerodynamic wheelsSilas_Greenback
Aug 20, 2002 9:00 AM
That would explain why more pros use the Mavic Cosmic wheels that are slightly heavier but have deep carbon rims. I still am skeptical that changing one component is going to make a world of difference, given the cost. Right now I am riding Campy Omega rims (which may be discontinued for all I know), DA hubs, and 32 DT 14/15 spokes on each wheel. My common sense tells me that aero wheels should not make a particle's difference in speed, but years of the "Tiger Woods golf clubs" advertising has probably resulted in some amount of brain wash. It is also a mistake, I found, to pick up a pair of such wheels, because they sure are slick and trick.
re: Aerodynamic wheelsmmquest
Aug 20, 2002 9:32 AM
ditto on the "don't pick em up!" didn't really want K's either and then I saw a pair...
check the numbersDougSloan
Aug 20, 2002 9:41 AM
A few internet sites discuss objective tests of aero wheels; check them out:

http://www.analyticcycling.com/WheelsConcept_Disc.html#Coefficeints of Wheel Drag

http://www.ultracycling.com/equipment/wheels.html

http://www.hedcycling.com/wheelchooser.htm

Bottom line: aero wheels are usually faster than normal wheels; the significance to you in terms of money spent and time saved can only be judged by you.

Doug
re: Aerodynamic WheelsChen2
Aug 20, 2002 9:49 AM
Interesting topic I think. About 5 years ago Bicycling Magazine actually tested the then popular aero wheels and compared them to a basic conventional wheel (this was back when that rag still did that sort of thing). Several pro or semi-pro riders rode the same course on each wheel set and their times were compared. I was in the market for some time trial wheels so I read the article closely, but have lost it since. The best performing wheels tested were the Mavic Cosmic Carbones and the Spinergy Rev X's. Both of these wheel sets tested .5 mph faster than the conventional wheels. They gave the nod to the Spinergies because they cost about 1/2 as much as the Carbones, which were $1000 in 1997. When the new models came out, Spinergy raised their price to match the Carbones. Rather interesting. I bought the '98 Cosmic Carbones. I've been riding them nearly daily until this spring I built some conventional wheels, King hubs, 32h Open Pros, Revolution spokes, 3X. I've tested myself riding the same training course under similar conditions on both wheel sets and every time I'm .5 mph faster on the Cosmic Carbones. This is a mostly flat 19 mi course with one short 7% hill. I can guarantee you I was trying my best on each ride, I have no reason to favor the Carbones, in fact I wish I could say that I'm faster on the wheels I built. Whether you think 1/2 mph is a lot or a little depends on your point of view. I think it's a lot on a time trial. The Carbones have a 57mm profile. The rim is actually aluminum with a bonded CF fairing. Mine have 16 bladed stainless spokes on each wheel. The newer Carbone rear wheels are built with 20 spokes.
~Al
re: Aerodynamic WheelsSilas_Greenback
Aug 20, 2002 10:55 AM
I am replying to you and Doug Sloan. Both the tests cited by Doug and your first-hand experience suggest a difference of at most 1-3% in speed, assuming that you were going over 20 mph on your time trial course. Doug is right that it does depend on one's values and the type of event you are riding. Reviews suggest that many of these wheels can be ridden in training on an everyday basis so that one reaps the benefit continuously. In the end, to change metaphors, it comes down to whether you like your sundae with or without the maraschino cherry on top. Put another way, it may serve as the final enhancement to a bike after the rider has topped out his potential through training. If you are riding more than .5 mph slower than your physical limit, a new wheelset is not going to result in a net improvement versus more training and effort. This should not come as a surprise, because everyone looks for a magic bullet or the easy path to wisdom. As I am writing this message, I am amused to see an ad for Cane Creek wheels in the upper left hand corner of the screen. The wheel issue has become literally inescapable.
You're remembering the test wrongKerry
Aug 20, 2002 5:23 PM
Chet Kyle did a "roll down" test where they found a long straight hill and got the bikes up to 25 mph at the start of a steady down grade. All of the speed improvements were calculated back to 25 mph. Runs were duplicated and conducted in essentially zero wind conditions. The argument is that there is no way you can trust a rider's power output to give consistent results, so you use gravity.

The best wheels were good for 0.4 mph at 25. I don't remember all the top wheels, but the DuPont/Specialized (now Hed) three spoke were among them, as were Campy Shamal, some Hed deep section, Zipps, etc. I don't remember the Carbones & Spinergy being in the top group, but they may well have been. Reference wheels were 32 spoke box section. The conclusion is that low spoke counts and deep sections are the key to aero performance. And if you want good cross wind performance, just shoot for low spoke counts (hard to do without a deep section rim, since the deep section makes for a much stronger rim).
You're remembering the test wrong?Chen2
Aug 21, 2002 8:01 AM
I'm glad your memory is better than mine. Do you have a copy of the test? I'm sure the Carbones and Spinergies had the best results in the article I referred to, but I thought they were .5 mph over the base case. The down hill test sounds right too. I will concede that your memory is better than mine.
~Al
We both remembered the test wrong!Kerry
Aug 21, 2002 4:43 PM
August 1997 issue of Bicycling (you made me go find it). Test was conducted by Pete Penseyres, not Chet Kyle. Best aero wheels gave 0.4 mph improvement: Corima 4 Spoke, Specialized/Dupont, Spinergy Rev-X. Next group (0.3 mph at 25 mph): MAVIC Cosmic Carbone, Torelli Wide Guy, Trek/Rolf. Next group (0.2 mph): Aerospoke, Shamal, Giant Carbon, Hed Jet/Jet Deep, Zipp 530.
Packrat!JimP
Aug 22, 2002 5:25 AM
Now we know that your are a packrat like the rest of us! I suppose you too have every part that you have taken off of a bike so you can have a used replacement if the need arises. Glad to know there are more of us. I'll have to show my wife that I am not the only one that saves back issues of mags.

Jim
Thanks, Where can I get tested for Alzheimer's?Chen2
Aug 22, 2002 5:44 AM
re: Aerodynamic wheelsAndreas_Illesch
Aug 20, 2002 10:50 AM
Aerodynamic wheels (deep section rim, low spokes number)won't provide aerodynamic advantages below speeds of 35 - 40 km/h.
consider which average speeds do you reach on short evening trips or long weekend trips.
if you're more into long trips go for light wheels instead of aerodynamic wheels.
consider the side winds on your trips. It's not funny if
you are on your way with high speed and a sudden strong side wind blows you of the road.