I can do most things on my bike having changed most parts over on my frame. The one thing I dont have a clue about though is bottom brackets. I have removed and serviced my current one, but what I dont know about is the different types.

I am planning a new bike build and at the risk or losing all credibility can someone very breifly explain….

are all bottom brackets suitable for all frames? (in UK), most are 68mm right? I think some are push fit, and some are threaded?

Ive read the wiki page http://en.wikipedia.org/wiki/Bottom_bracket which explains a lot, and it seems the main compatibility issues are between bottom brackets and cranks, not between bottom brackets and frames?

So can some one explain the different bottom bracket frame interfaces?

What frame is it?

new build is gonna be kinesis crosslight pro 6, but all the tech stuff just says 68mm UK.

Aye – that’s a standard, threaded BB the likes of you get with most sets of cranks.

so any threaded BB will work?

was looking at this:

I think you’ve picked the only one that isn’t compatible.
GXP uses two different size bearings and will only work with GXP cranks.

GXP will not work with Shimano cranks…it is unique to Truvativ cranks and has different size (axle bore) bearings left and right.

Most cranksets come with a BB that will fit 68 or 73mm shells with the British (left and right handed) threads.

Consensus seems to be that GXP and Race Face will last a few wet days, Shimano Deore a bit longer, and for that all-week ride, go XT or XTR from Rosebikes for value.

What is now on your shortlist?

PaulD

I think you’ve picked the only one that isn’t compatible.

with the frame or any other cranks?

I wanted a SRAM force road chainset, so wouldnt that work fine? what are my other options for BBs for SRAM force chainset?

The threads in to the frame will be the same, it’s the bearing size/crank diameter that’s odd.

Aren’t road BBs 100mm ?

Road BBs are for a 68mm shell, so will not fit a 73mm BB unless you change the polymer spacer/seal.

Lots of BS about different sealing versus MTB, but knowing Shimano they are probably directly comparable bearings and cups with the different spacer.

SRAM Force comes with a GXP (or optionally BB30) BB included.

http://www.chainreactioncycles.com/Models.aspx?ModelID=75588

PaulD

so is BB30 better than GXP?

whats the difference?

BB30 is a new ‘standard’ that has larger bearings which are pressed into the frame, so if your frame is 68mm Threaded, then you will have some difficulty fitting a BB30.
The chainsets are otherwise the same, just supplied with a different pair of bearings.
So, if you get a BB30 frame later, just get bearings and move the cranks over.

PaulD

If you’re buying SRAM road cranks, get the GXP bottom bracket. Sorted.