Bottom Bracket axle broken - replace with same or ceramic?

You can get ceramic bearings but not ceramic axles. Is that what you mean?

Quoted post said:

Originally Posted by Bigbananabike [IMG]/img/forum/go_quote.gif[/IMG]

My 10 speed 105 axle has broken.
Should I replace with the same or get ceramic (its become my race bike too so some free speed would be nice) ?

What is a good ceramic brand?

BBB ;-)

Some of the ceramic bearings now are sufficiently durable for bike use, but you're not going to see a lot of free speed. Lets say you put out 200 watts and that ceramic BB bearings will save you 5 watts. That means now you lose 5 watts less, so you get an effective power increase (after losses) of 2.56%. In terms of velocity, your velocity would theoretically increase by 0.847%. Not exactly a huge jump......and that's in a perfect world where ceramic BB bearings save 5 watts over standard bearings. I just picked a number out of the air.
Campagnolo claims their CULT bearings save 3.5 watts, so those bearings would give a speed increase of 0.59%. Again, that's not very huge.

If I had to pick ceramic bearings to use, my first choice would be CULT bearings (I have Campy cranks), followed by HSC hybrids (inexpensive but perform well) and Ceramic Speed bearings (tres expensive but may very well be the caviar of the ceramic bearings for bikes world). I have heard very little that's good about Enduro bearings and a lot that is not good, but I've never used them. Frankly, I'd put the money elsewhere in the bike or in training rather than dump money in ceramic bearings.

Quoted post said:

Originally Posted by alienator [IMG]/img/forum/go_quote.gif[/IMG]

Some of the ceramic bearings now are sufficiently durable for bike use, but you're not going to see a lot of free speed. Lets say you put out 200 watts and that ceramic BB bearings will save you 5 watts. That means now you lose 5 watts less, so you get an effective power increase (after losses) of 2.56%. In terms of velocity, your velocity would theoretically increase by 0.847%. Not exactly a huge jump......and that's in a perfect world where ceramic BB bearings save 5 watts over standard bearings. I just picked a number out of the air. Campagnolo claims their CULT bearings save 3.5 watts, so those bearings would give a speed increase of 0.59%. Again, that's not very huge.

If I had to pick ceramic bearings to use, my first choice would be CULT bearings (I have Campy cranks), followed by HSC hybrids (inexpensive but perform well) and Ceramic Speed bearings (tres expensive but may very well be the caviar of the ceramic bearings for bikes world). I have heard very little that's good about Enduro bearings and a lot that is not good, but I've never used them. Frankly, I'd put the money elsewhere in the bike or in training rather than dump money in ceramic bearings.

Thanks for the good reply.

The bike shop mechanic said he wouldn't spend $ on CBs either and thought as an upgrade DA would be a better bet.
[FONT= times new roman]I’ve seen some ceramic bearing sellers claiming 8% friction decrease – which may be true but seems hard to believe. [/FONT]

[FONT= times new roman]BBB[/FONT]

If you can break something like a 105 crank axle then worrying about ceramic bearings should be the last thing on your mind. 😉