My shimano external bb (MTB)needs replacing and i have a spare ultegra bb from my road bike. Is there any reason why i can’t use it on my MTB? Is it less durable than any given MTB-specific bb? Or, is it all about marketing?

advice please

thanks

only one way to find out…but I reckon it’ll be fine.

I’ve had no problems so far using a ‘road’ Hope BB on an MTB if that helps.

They’re not the same though they may work. For a start, the mtbs are designed for 73mm shell with spacers to take up the space for 68mm. Road are for 68mm and iirc will therefore have less thread in the frame if used on an MTB.

17 quid posted for a brand new XT from a 2011 chainset still in bag if that interests you!

trail_rat £14 posted and I’d take the bb,

Gareth

I was in the same situation when the BB died on my downhill bike. Used the Ultegra I had spare which lasted longer than the original RacFace X type.

The Ultegra has since been worn out and replaced, withno negative effects that I have been able to notice.

been using ultegra bb’s on hardtail and bouncy mtb’s with no problems.

Trail rat I will give you the full £17 for it please.

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MM

You can get it to work but Clubber is right. The other thing to take in to account is that the road cups are slightly wider, which can cause problems with chain line etc.