Triathlon - Spoke or wheel ocver/farings

Don't know the correct terminology here...."cover"...."faring". I've heard of some refer to these wheel bolt-on covers as the "poor mans equivalent" of a disc wheel. Others have pooh-poohed them. Opinions? Seems that they are cheap enough in the $50-100 range. For that price...do you get some benefits of a true rear disc? If true....How much benefit?

Thanks

Kurt Willett over on Biketechreview.com has some wind tunnel test results that he sells for about $20. He tested a large number of wheels, both front and rear. Some rear wheels were discs, and he also tested rear wheels with a wheel cover (a CH Aero, commonly sold by Rich Sawiris over on wheelbuilder.com). With the possible exception of Zipp's new disc wheel announced at Interbike a few weeks ago, a wheel with a cover properly fitted and attached is the aerodynamic equivalent of a 'real' disc wheel. By properly fitted and attached, I mean that border of the cover where it meets the wheel rim should be smoothly taped and the valve stem access hole should also be taped over.

Zipp claims that their new Sub9 tubular disc wheel creates 80 grams of lift at a yaw angle of 15 degrees, which, if true, is a remarkable achievement since most aero wheels simply reduce drag but create no lift.

The prevailing wisdom indicates that one would be a fool or rich to actually buy a disk over a cover.

Thanks for some opinion.

I have a Ch-Aero. Wife is faster than I. She did a sprint a couple of months ago....was not a windy day. I spent the night prior bolting the cover on. A little more difficult than it looks at first. Bolts were barely long enough. There was the slightest tendency for the cover to "pucker" as you looked around the rim circumference. Centering was a bit of a task also. The Chaero seems to come prepped for placing on a short boxed rim....if there's any depth to your rim, some modification may be needed.

She "felt" if gave her nothing extra on the course. She noticed nothing different in performance. Yes, I know new course is no comparison. I asked her to compare on our practice course. She was looking to buy a minute off her time. I've asked the question as I'm wondering if I can purchase some time in this fashion.

From what I've read here....some time appears to be had for some $$ by going aero with the helmut.

I'd say the cover gives you most of the aero benefits of a true disk. aero cover is way cheaper. Disk is lighter. Disk makes cool whoop sound.

covers are illegal in some tts if your interested in doing like state time trials, nationals and such but i belive your good in tris

If you go to wheelbuilder.com your cover will be custom made for the wheel you want to put it on. So say you have a set of 404s. Now for under $100 you have a disk set up for it as well. In any tri that you are using a disk, weight is obviously not an issue. even then, if you are using a box rim, it is all rotating weight, which is better for the riding we do.

Everything I have heard comming from wind tunnel testing is that the covers are as fast, or faster then certain disks. It is definatly one of those things that is worth it. I wish I knew about these before I bought my disk.

Now with the TT Helmets. I dont follow this forum that closely anymore. Though I assume it is a topic that has been beaten like a dead horse. Just search for it. In short, they are definatly worth it.