Triathlon - Wheel covers

I'm thinking of getting a wheel cover for my QR tri bike. Here's my question: will the wind push me around more if I have a wheel cover? I am afraid of having problems on a windy day. Also I understand the single most useful purchase in terms of reducing drag would be an aero helmet, then a wheel cover - any thoughts on that?

Thanks

Yes, the wind will push you around a bit with a disc cover, but you'll also be a lot faster with the disc cover, even in windy conditions! And, the wind's effect on the rear wheel is much less than the wind's effect on the front wheel. If you're not running a super deep (80mm or more) front wheel you should be able to handle your bike in anything up to, say, 35mph winds with no problem.

An aero helmet certainly makes financial sense (as does a wheel cover), though it's often tough to tell whether an aero helmet or race wheels gives you more speed (it usually depends on the rider). Also, some of the aero helmets out there aren't suited to certain body types, make sure you get one that "fits" the contour of your back with your head in the right position!

How do I do that?

A buddy of mine tried wheel covers, but they didn't work very well at all for him. Hard to mount, and kind of heavy too.

IMO, you'd be better off saving up for a real disk wheel with tubular tires. Lighter, higher pressures, more aero...and, thus, faster.

Lighter, higher pressures, more aero...and, thus, faster.

One out of three right, and the conclusion highly doubtful.

One out of three right, and the conclusion highly doubtful.

FWIW, my Zipp 900 disk:


weighs only 950 grams
uses tubular tires that I run at 175 lbs
is definitely more aero


and, thus, faster.

BigCat, to answer your question about getting the helmet that "fits" you, you should probably go to a shop where you can try them all on while you're on your bike in the aero position. Simply put, try to select the helmet that provides the most seamless transition between helmet and upper back, for the smoothest laminar flow of the air leaving the helmet.

About tubulars, the problem with tubulars for triathletes (and I run tubulars as race wheels, so I'm not biased against them) is the following disadvantages:

- Pain in the Ass to install
- Hard to get as true as a clincher
- More expensive for equivalent quality

outweigh the advantages:

- Tubulars can be run at higher pressure (it's rarely necessary to run much above 140psi in a road race or tri anyway)
- Tubulars can be changed quickly, if glued right and you're carrying a full spare tubular
- Lighter (doesn't really matter in a tri)

FWIW, my Zipp 900 disk:


weighs only 950 grams
uses tubular tires that I run at 175 lbs
is definitely more aero


and, thus, faster.

Like I said one out of three. Tires at 175 psi are slower than at 120, tests show no difference in drag between disks and wheel covers (and I don't know how you could tell the difference yourself), and since weight has such a minor impact except for courses ending with very steep climbs, thus probably not any faster.

Like I said one out of three. Tires at 175 psi are slower than at 120, tests show no difference in drag between disks and wheel covers (and I don't know how you could tell the difference yourself), and since weight has such a minor impact except for courses ending with very steep climbs, thus probably not any faster.

Right...that's why all the pros are running clinchers and wheel covers. :rolleyes:

If you've got links to studies showing no difference between wheel covers and disk wheels, please post 'em.


FWIW, my buddy with the wheel covers ended up sending them back for a refund. They were a pain in the butt to mount, and wouldn't stay put. For his next major TT, he's borrowing my Zipp 900.

Right...that's why all the pros are running clinchers and wheel covers. :rolleyes:

If you've got links to studies showing no difference between wheel covers and disk wheels, please post 'em.


FWIW, my buddy with the wheel covers ended up sending them back for a refund. They were a pain in the butt to mount, and wouldn't stay put. For his next major TT, he's borrowing my Zipp 900.

My $.02

All of the downsides to running tubes are mitegated by having a mechanic and a following car, few triathletes seem to have this support.

I will give you this, a Zipp or comparable disk is going to be marginally lighter and aero, small enough margin that unless your getting it for free its simply a waste fo money to go for the real disk over a cover. Pros get them for free, hence its worth it for them.

My wheel cover to took 10-15 minutes ot install the first time, it takes a chain whip, cassette socket and two nickels, its not brain surgery.

If you've got links to studies showing no difference between wheel covers and disk wheels, please post 'em.

http://www.google.com

http://www.IveGotNothing.com

fixed.

fixed.

you misspelled it. http://www.ImTooLazy.com

SSP, asgelle is kind of right.

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Tubulars are on average, slower - http://www.biketechreview.com/tires/AFM_tire_crr.htm

Higher pressure doesn't have more rolling resistance, there is a point of diminishing returns around 120 psi. And it has been shown that on bumpy roads your higher pressure tires will take more energy to move forward because of loses in up and down movement. So Asgelle is right in this regard.

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Disc covers may be as effective as your Zipp, asgelle is being vague because of confidentiality purposes I believe. I suggest you search and ye shall find.

Whats interesting is that your flat disc is actually now one of the least desireable shapes. Zipp/Hed's new bulge shape, or a lenticular shape has been shwon to be faster under real world conditions. A disc cover is indeeed lenticular. Additionally, JoshatZipp has stated that wheelcovers installed correctly can be very effective.

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Yup it's lighter. And by my calcs with analyticcycling.com 8 kg weight loss is worth about 10 seconds in a 40k hilly tri.

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To the OP, get a wheel cover from wheelbuilder.com (he'll cut to fit your wheel), get some electrical tape to "smothe the edge", and get whatever aero helmet feels nice on your head and doesn't stick up in the air when you ride.

May add another disadvantage of a wheel cover compared to a disc?
It doesn't make whooomp whooomp whooomp whooomp when passing someone :-)