What is the benefit of ceramic bearings for my Mavic Cosmic Carbone SL? They are not cheap.....but is there any differnece between brands? There are some for $240 on ebay...and some for $120 on ebay. What will I gain/lose by swapping over...and do different brands really make any difference!?!
ADAM

The idea is to reduce rolling resistance by using harder materials. Imagine if your normally 120psi tires are run at 50psi. There would be lots more resistance. Now, imagine the same tire at 300psi. If it could hold 300psi, it would have a very tiny contact patch. It wouldn't handle or ride worth a crap, but it sure would roll pretty free. Ceramic bearings (silicon nitride I think) are harder than steel and I believe they hold a round shape better. Can't say why there is a price difference. Name brand vs. off brand?

Would you see a difference? Lance and the guys he competed against would, but I don't know about mere mortals...

Well, Mavic ceramic bearings are supposed to "add[] 20m-40m per 1km ridden". If my math is right, that means instead of going 30kph, you'll go 30.6-31.2kph. I think I've read that the effect is more noticeable at lower speeds (i.e., before air resistance becomes the dominant factor).

Si3N4 has good fracture toughness I believe, and probably good surface roughness as well. Ball to ball friction would be low, and would not wear like steel on steel. I think mountain bikes would benefit more due to greater dynamic loading. I think even the cheapest ceramic bearings would be fine, cause if the factory can manage to even make the dang stuff, then what you're buying is better than steel.
As for the 'investment' factor, I'd say you're doing better getting good bearings than by gram counting. A bike is just a way to connect you to the wheels.
Now if you could get a bearing race made of partially stablizied zicronia, that would be the bomb.

-n

Acme Ceramic Bearing Company?