Ceramic wheel bearings, yay or nay? Also a question on grease

[jones21290]

Hey guys, I'm new to the sport but wanted to get a decent set of wheel bearings. I already have the old ones out as the wheel didn't spin completely freely. The hubs are fine, I was just scheming on getting some ceramic bearings. Are they worth the extra cost? Also, I've found some graphite lube on ebay specifically for ceramic bearings, is it necessary to use this kind? Thanks, Alex.

 

[tafi]

There are bearings and there are bearings, but unless you are racing, ceramic bearings are not worth the cost.

Are yours sealed or cup and cone type?

The balls themselves are rarely the reason for a bearing not spinning freely. Far more likely to be bad adjustment of cones or worn/pitted races. Using too thick a grease can also cause losses.

As for graphite, I have no idea.

 

[oldbobcat]

Hey guys, I'm new to the sport but wanted to get a decent set of wheel bearings.

Ceramic bearings for bikes are application-specific, primarily for making well-maintained and efficient expensive hubs even more expensive and slightly more efficient.

It sounds like you're just trying to restore an abused or damaged hub. If that is the case, you can rebuild the hub with a new steel axle, cones, and balls as needed. Or you can just buy a new wheel. Your local shop should be able to get the correct replacement parts.

And graphite should never be used as a bearing lubricant on a bicycle. Graphite is too abrasive. Use bicycle or automotive bearing grease in steel bearings, closely follow manufacturer's recommendation for ceramic.

 

[531Aussie]

Hed used to state on their website that their testing found reduced drag with ceramic bearings while not under load, but under load, they could not measure any difference with steel balls. I can't find it now, and it's no longer on the same link.

I also noticed that HED have changed a bit of their 'aero' spiel. They used to say that wheels created approximately 0.25lb of the ~6.5lb total drag created by a person on a bike, but they've changed it to say that wheels generate ~0.5lb of the 6.5lb. I wonder if the change was a result of extensive testing, or due to some cajoling from their sale department

 

[daveryanwyoming]

... They used to say that wheels created approximately 0.25lb of the ~6.5lb total drag created by a person on a bike, but they've changed it to say that wheels generate ~0.5lb of the 6.5lb. I wonder if the change was a result of extensive testing, or due to some cajoling from their sale department

Probably marketing driven, but either way it's a total swag based on a lot of assumptions. For starters rider position and size is the big ticket item when it comes to aerodynamics and you can't say that the drag on any given rider is 6.5 pounds any more than you can say all riders weigh 70 kg or any other arbitrary number. If you're sitting way up in the wind on your tops or on a 'comfort' aero bar fit or are a really big person then the wheel savings is likely to be swamped out by your overall frontal area's contribution to CdA. You can't just linearly add up the isolated drag of each of the components like wheels, frame, helmet, etc. and come up with the overall drag for the whole bike-rider-position-equipment system.

Either way I'm sure their wheels save quite a bit for a reasonably sized rider set up in a good TT position, is it half a pound of drag out of a total of 6.5? Probably not for an arbitrary rider but there's definitely some savings there...

-Dave