Originally Posted by
csport
I am slowly building a Surly DT, decided to use hybrid ceramic BB (with one ceramic bearing),
https://www.somafabshop.com/shop/ird...=967#attr=2680
Not as expensive as a full ceramic BB, they also have sales from time to time.
My motivation for it was longevity and resistance to mud. It is probably a nice thing to have (if it works), OTOH I do not think a regular BB will catastrophically fail (lock up) in a instant. I expect it to creak and grind for a while before it completely fails.
Agree with what the others say about performance. The diameter of the BB is small. BB-MT800 or BB-R60 are less than 4cm in diameter - the radius of the cartridge with the bearings is less than 2 cm. For a 90 rpm cadence the angular speed is 90/60 * 2 * pi = 10 s^{-1}. Then for every kgf (10N) of drag in the bearings the torque is 10 * 0.02 = 0.2 N*m. The power is 0.2 * 10 = 2W.
And in the reality the drag is probably much lower, then the power loss in the BB is less than 1W.
Wow thanks for the amazing information! I very much appreciate everyone that takes the time to respond. I have noticed more and more that the difference for a more expensive BB seems to be longevity and not much if anything at all in the way of performance to gain. Since my bike is only a few months old and I don't ride in the rain, it probably doesn't make much sense to spend on a BB for now.