Real difference between 35mm and 45mm carbon wheels?

[BigPoser]

I've been checking out the loooooong carbon wheel thread and have been wondering what the real differences are between either a 35 or 38mm rim vs. a 45mm rim. Are the aero benefits really that noticeable? From that I can tell when comparing the different depths with the same widths, there is about 100gr difference however.

Any thoughts on this? Is a 45mm rim worth it?

[Marin]

about 10mm

[kgt]

Just choose whatever looks better on your bike IMHO.

[Marin]

Sorry could not resist.

I have a set of 50x23 1330g "V-Shape" wheels. I also had a set of 38x25 1540g "U-Shape" wheels.

The most noticable difference was that the 38s were unaffected by crosswinds. No idea if they were faster, that's something you can't feel, or even measure without a pretty sophisticated protocol.

I really liked the 38s, but sold them to build a new set of 35x25s that will be a bit ligher.

All you can do is read up on tests. My recommendation would be to let looks and weight decide, and to get U-shape rims.

[btompkins0112]

^ +1.....short answer is no difference, except for weight of course.

[glepore]

The crosswind difference above likely had more to do with the shape than the depth. My 50's in both wide v and u are unaffected by crosswinds under say 30mph, at which point any deep wheel would be affected.

[Bourquek]

For what it's worth, I have ENVE 3.4 which are the 35 front, 45 rear and I have noticed being pushed a little from cross winds on steep straight descents. I sometimes wonder if a 35 rear would have made a difference or not. Hard to say without experimenting.

[boysa]

I experimented with Enve 1.45 and 1.65, and the most stable combo for crosswind was 45 front & 65 rear. Much better than 45/45. I was given the idea by a Zipp rep back at NAHBS '10. He sold me on the theory the larger rear would act as a rudder/stabilizer, and lo and behold he was right. In heavy wind, it's more of a steady push than a quick shove. Sure enough, Enve soon after came out with staggered sets.