Road Cycling - Aero Wheels?

OK, I have a lightweight set of racing wheels, but I am interested in the best (cost-effective) aero wheels.

My racing weight varies from 170-190lbs, and I do a 40k TT in ~1hour.

I MUCH prefer clinchers to tubulars.

What wheelsets are recommended for maximizing my 40k times (flat course)?

If your preference is custom-built, please provide details: rim, hub, # of spokes, etc.

Thanks!

Do you know what the most un-aerodynamic part of a bike is? Nothing, You are. By far, the largest aero drag is caused by the rider.
You would get alot of benefit from fine-tuning your aero position. Alot of riders get it wrong. Look at your head, chest and arm positioning.
Wheels:
The fewer spokes the better. The shorter spokes, the better.
Zipp, HED, Mavic,etc all make good aero wheels.

If you care only about speed, and not about longevity, reliability, or cost-effectiveness, by all means go for reduced-spoke-count wheels. However, if you value strength-to-weight ratio and durability, the more spokes, the better. Personally, I shall not use fewer than 32 spokes per wheel.

I'd assume with a ~1hr 40k TT he already has a fairly aero position on the bike, especially if he is now moving to aero wheels.

By far the most aerodynamic is a lenticular disc (a flat disc is a little less aerodynamic, but still better than a spoke wheel). With the best setup being a 3 spoke wheel (like the HED) in front and the disc in the back. However the disc isn't that aerodynamic in a cross wind, along with being semi-unstable (in a really stiff cross wind the typical aero wheels aren't as aero as a normal 32 spoke wheel as well). It can also be a pretty pricey setup, I've seen the HED 3 spokes in the mid $400 range for the front wheel (there are other makers of 3 and 4 spoke wheels though), and I've seen disc's run anywhere from mid $300's to $1200+.

A few links to some aero wheels besides the big guys (Zipp, HED, etc);
http://www.nimble.net/ 3-spoke aero wheels
http://www.rennmultisport.com/main.htm $320 flat disc wheel
There's another maker, xtreme I believe...but I can't find their website, they were very reasonable price-wise from what I remember.

Check out for some good data;
http://www.cervelo.com/qa/article5.html
http://www.bicyclesports.com/index.html (go to the technical section).
Both have some good information on different aero aids, and both do time estimates based on 40k TT's (the second one bases a lot of research on wind tunnel results).
http://www.bsn.com/cycling/WheelAerodynamics.html


Andrew

re: "I am interested in the best (cost-effective) aero wheels"

There are several websites online (the links escape me now) where people have created homemade disc wheels...by several methods...all of them very inexpensive. In one instance, a guy used a normal set of spoked wheels and melted hobbyshop kite material around the edges...it looked very well done, he enjoyed it, but noted also that you couldn't easily adjust the spokes (he left a concealable hole for presta valve access). If you did this to a high spoke-count wheel, it could be a good thing.

I'll see if I can find those links...one was on a recumbent site I remember.

:beer:

Good point, you can even buy covers, I think Excelsports sells them for like $50-60 for the CH Aero covers, I've never seen any aero data on them, but I'd imagine you would get a fair amount of the benefits (plus they snap on and off so you can still work on the wheels when needed). The downside is weight of course.

I found a couple of links to DIY wheels covers;
http://wisil.recumbents.com/wisil/wheeldisk/wheeldisk.htm
http://www.angelfire.com/realm/cvccbikers/misc/wheel_cover.html

Andrew

good find Andy!:)

thick 1" steel rim with narrow steel hub with unsealed steel bearings and 0 guage steel spokes.

Indeed, work on your aero positioning before worrying about the wheels (and then, spoke count probably matters more than aero shaped rims).

On the flats, if you have a frontal area of .35 meters squared, you'll need to crank out about 369 Watts to go 40 kmh. If you were to get aero wheels, you would be able to reduce the frontal area by only a fraction. But, let's be super generous and say that your total FA is reduced to .34 m^2. That means that with those 369 watts you could go 40.37 kmh.

But, if you go into a better aero position, you could conceivably get your FA down under .30 m^2. That would mean you could go 42 kmh with the same wattage.

Your kilometer-age may vary.

Cheers,
Jamie