In my quest to get a disc wheel for the 2009 triathlon season a few things bother me. Weight and versatility.
I have read all the posts on weight vs aerodynamics but for an ex-road racer the “weight does not matter as much” cool-aid is often hard to drink (although I am coming around).
Versatility - If I buy a disk I will probably only use it 4 times this year. Seems like a bit of a waste. Perhaps I should race more…
To come to a solution to the problem I was thinking why not buy a quality lightweight clincher and then a wheel cover? (Rolf Elan + wheel cover). This total weight would be about the same as most disc wheels (or lighter) but give me another set of wheels to ride on when I do not need the disc.
What is the advantage of a true disc wheel versus a wheel cover?
What am I missing here? (Why would anyone buy a disc?)
Have people quantified time savings on an IM course from going from a deep dish wheel (808) to a disc?
BTW. My current race wheels are 808’s which are a bit heavy already so I did not want to add a wheel cover.
I only ride clinchers. I dont want to get into this debate but I used to race tubulars and will not go back. An expensive experiment.
My A races are 1/2 and full IM’s.
Your 808+wheelcover will be faster than any standalone disc (including the Sub9). It will be marginally heavier than a standard lightweight clincher rim + cover but again, more aero.
no advantage of a true disc wheel versus a wheel cover, except any difference in weight (which usually argues for the wheel+cover)
If you want the time savings, scour the zipp site for their comparison over a 40k for each of their wheels and then extrapolate out to IM distance.
bottom line, buy a cover for your 808 and rest confident that it’s the least expensive, most aero, and most versatile combination you can have. easy enough?
Thanks for the quick response.
Question: Why would an 808 with a wheel cover be faster than a standalone disc? Would this not imply that Zipp is doing something wrong in the construction of their discs? (intuitively this does not sound correct)
808 With a cover wont be faster than any other wheel with a cover. You may as well get a 32 - 3x with a cover as opposed to am 808. The wind wont notice. Then again, neither will your finish time.
I’m of the type that would rather avoid the fuss w/ putting the cover on and taking it off several times over a variety of races… for a little extra $$, prefer to have 2 separate wheels; much easier to swap out quickly if/when I feel the need. Originally figured on just getting a regular wheel + cover since it seemed pointless to spend a bunch for a nice aero wheel and then cover it up, but then I got a used disc pretty cheap. As near as I could figure, it weighed about the same (if not slightly less) and didn’t cost any more than what I was looking at for wheel + cover individually w/ shipping, etc, factored in.
I guess the one big advantage to the wheel + cover in my scenario would have been repairability… If I wrecked it or did something stupid, the regular wheel would likely be salvageable (maybe replace some spokes or rim and true/re-build), whereas a cracked/wobbly disc is pretty well toast beyond replacing hub bearings or something.
carefully read through joshatzipp’s postings on this forum. he implies that the 808 + wheelcover did better than the sub9 disc in the tunnel. This is probably why the sub9 disc is extremely similar to an 808 with a cover (although its a bit closer to a 404), and its probably what gave them the idea in the first place.
Consider doing this. Buy the strongest, lightest, used rear clincher wheel you can find and PERMANENTLY bond the disc wheel covers to the wheel’s spokes and around the hub area. In the worst case scenario you’ll break a spoke and be out another $65 for replacement covers.
Back in the 80s I did this and marketed disc wheels made this way and I have to say I never had a wheel go out of true or broke a spoke. I had to spray paint the covers a lighter color because the heat of the sun would cause them to warp on a really hot and sunny day.
Maybe it’s luck but I think the process of bonding the spokes to the covers fortified the spokes. I used foam insulation spray and I promise you that your covers will never come loose or rattle if you do it right. It’ll even sound like an actual disc wheel if that matters.
There are at least two sources that have indicated certain wheelcover setups are faster than certain disc setups in wind tunnel testing, across a range of raw angles.
This may not be universally true but the N=2 testing has been a win for the wheelcover aerodynamically both times.
It is really the way to go imho. If I had infinite money I would buy a Jet clincher disc instead since its a bit nicer looking. (it is essentially a permanently bonded wheelcover)