For 150 euro more I can buy mavic wheels with sfk ceramic (hybrid) bearings here at a LBS. Is that worth the money? (1150 euro for cosmic carbones with skf ceramic bearings)
The company making these special bearings is SKF. Their customers for these bearings vary from avionics (Boeing, Airbus) to L'Aerospatiale, medical appliances, etc.....You get the picture...
Either way, ceramic ball bearings come in two main categories: full ceramic balls and housings and what is commonly refered to as the hybrid bearings: ceramic balls running in hardened steel bearing housings.
As an upgrade to an existing hub only the hybrid type is used, the ceramic balls decrease friction by about 90% (not always that much but still) and continuously hone the bearing reducing pitting in the process.
This is probably the upgrade you're talking about as offered by Math Salden in Holland.
Overhere (Belgium) we can buy the bearing balls as an upgrade for BBs and hubs. The distributor has the exclusive rights for SKF ceramic bearings as applied to bicycles for a couple of years so no need to search through other channels.
Whether that's worth the additional extra 150 Euro on top of the wheelset is open to debate and entirely up to the customer. The asking price given the materials and labour involved certainly isn't exorbitant.
However, I would only consider this if the wheelset is already of impecable pedigree and if the company doing the upgrade is willing to pick up the original manufacturer's warranty.
Besides that, yes, it should make for a noticeable improvement; anything that reduces friction should.
One caveat: never use lithium grease with this type of bearings as it will tend to offset the reduced friction, use PTFE loaded oil instead.
Full ceramic bearings within a ceramic housing don't even require any grease or oil to be present, friction is that low.
- Are bearings in a ksyrium SL from 2003 easy to replace? And what kind of bearings do I have to buy for them?
Once you know how it's not that hard to do but you need the tools and the correct parts. If it were my wheels I'd send them to a competent mechanic and be done with it.
When I am correct: hybrid ceramic bearings do not have any weight advantage compared to normal bearings because the balls are made from steel but have an ceramic layer.
Not correct. See the explanation above, the ceramic balls are made entirely out of silicium nitride. Ceramic housing could be made with just the cage made of ceramic, the housing only keeps the bearing assy together.
Full ceramic bearings do have a little weight advantage but are very very expensive?
However you'll gain more from the reduced friction in everyday use then you would from losing say 500g weight off the bike.