What is better a Disc or Deep section wheels ?

The pros seem to use a deep sectioned rim for the front and a disk on the rear, so I would imagine that would be the optimal setup given the rules regulating TTs.

badkarma said:

The pros seem to use a deep sectioned rim for the front and a disk on the rear, so I would imagine that would be the optimal setup given the rules regulating TTs.

It can really depend on conditions as well. Usually full disc rear and deep front are the way to go, as well as with tubular tires. If its REALLY windy, some may prefer deep dish vs full disc because of side drafts. I think that going from regular wheels to full disc wheels you can save something like 2-3 mins on a 60 minute time trial, does that sound right to anyone? I know I left that info somewhere....lemme find it...

tomblack10 said:

Hi

I am wanting to buy a new disc wheel for the 2006 season. I will be mostly doing 10mile time trial but also a few 25's.
The problem is I dont know wether a set of deep section wheels e.g. cosmic carbone wheelset is more aerodymanic and more efficient to my than a e.g. Renn Disc wheel .

Does anyone know ? What's better ?
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Disk is more aero but may be problematic in strong winds and weight may be an issue in time trials with a lot of climbing. If your TTs are flat to rolling, you should keep your Renn for the rear. For the most aero combination, use a Tri-spoke or deep rim low-spoke count wheel on the front.

If focused on TT improvement, more bang for the buck would be spent on better aero position on the bike. Being that your body is the biggest source of drag, not the machine, anything you can do to make your back flat and to have your kit as slippery as possible would be more results effective than in putting a disc wheel on the rear. Almost necessary is for someone else to evaluate your position on the bike. You can't see yourself so you can't tell how aero you really are. Minor position changes can make a big difference. This is based on wind tunnel studies of athletes.

This is why an aero helmet is used by the pros. This is why the pros also use shoe covers. Everything possible is done to reduce drag. The thing is, the wheels are only a small part of the equation.

Unless the course is relatively flat and its not very breezy, I would say go with deep sections. Reason is, discs were never meant for climbing by any means. IMO, any time you make up on the flats will be lost in the climb.

TWOPBikeGuy said:

It can really depend on conditions as well. Usually full disc rear and deep front are the way to go, as well as with tubular tires. If its REALLY windy, some may prefer deep dish vs full disc because of side drafts. I think that going from regular wheels to full disc wheels you can save something like 2-3 mins on a 60 minute time trial, does that sound right to anyone? I know I left that info somewhere....lemme find it...

I think its around 2 minutes at 27mph if I remember correctly, over a 40k course.

I have a set of Zipp 404s, a set of tri-spokes and a Zipp disk. I chose my set-up purely on the course and conditions.

Calm day, flat course - the rear disk and a front tri-spoke is smok'in
A little wind - I will run the disk + 404 in front
A little more wind - I run the tri-spoke in back + 404 in front
A little hilly - I run the 404s

If I could only have one option, I would probably go with the 404s all around. We have enough wind in my area that there are times when a disk would scare the mess out me.

This may be of interest:

http://www.velonews.com/tech/report/articles/9608.0.html