Trek Bontrager bottom bracket problem

lfoggy said:

I've got a Trek with a Bontrager chainset with a 'hollowtech' design with the new style bottom bracket where the berarings sit outside the bottom bracket shell and the axle is connected to the chainset. The non-drive side bearing is making horrible noises and needs replacing but I am having trouble working out what new bottom bracket to buy. The chainset is a Bontrager Race Lite. I'm happy replacing them myself but just need some guidance on what to order. (I know the bottom bracket shell is 68mm with an English thread.)
Is there any standardisation between Shimano and the other makes, i.e. if I buy a Shimano BB will the Bontrager chainset fit ?

I'm not sure if the Bontrager crank is a GXP, but even if it is, the non-driveside cup-and-cartridge from a Shimano Hollowtech II BB can be interchanged ...

BUT, you can simply replace the cartridge bearing(s) ... the size is marked on the plastic seal (i.e., 6805-2RS for Shimano & FSA) ... it should probably cost you less than £2, but it might be a little more. The replacement cartridge will cost less at a "bearing" shop than from your LBS. Like "regular" bearings, cartridge bearings come in different "grades" ... some have seals on both sides ... some cartridge bearings do NOT have seals on both sides ... some do not have any seals at all.

If the crank is GXP, then the driveside cartridge is a different size.

BTW. You CAN service the cartridge bearing(s) in your BB ... it requires gently (?) lifting a part of the seal on-one-side OR completely removing/discarding it (discard ONLY IF you are planning on periodic re-greasing) ... flushing out the existing grease OR squirting a little WD-40 into it ... "drain" & squeeze some fresh grease under-the-seal ...