Can i use MTB BB in...
 

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[Closed] Can i use MTB BB in road frame?

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 scud
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Sorry if this has been asked before, I have a lovely new Reilly Gradient "gravel" frame with 68mm wide threaded BB shell, i also have a new Rotor ceramic BB in spares box, but going to fit it, i realised it is marked "MTB".

Am i right in thinking MTB BB are not as wide, and if so can i simply space it out?


 
Posted : 16/04/2018 4:25 pm
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I just put an XT BB on my road bike to replace an Ultegra

I just reused the plastic middle spacer as XT was different length.


 
Posted : 16/04/2018 4:49 pm
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The centre tube is definitely different, but I think I’ve heard there’s a difference in the cup depth too?  Really not sure. I’m quite surprised there isn’t an easily googlable answer on this.


 
Posted : 16/04/2018 5:10 pm
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Probably yes.

I've put an XT BB / chainset into a Genesis CdF to replace the Sora one supplied.


 
Posted : 16/04/2018 5:24 pm
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The external element of the cups are a different width - unfortunately I can’t remember which one is wider, the first I found out was when I copied he expected setup but the wee hole for the safety tab wasn’t far enough out


 
Posted : 16/04/2018 5:38 pm
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MTB normally us a longer centre tube and longer threads.


 
Posted : 16/04/2018 6:08 pm
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I'd you're using square it's a yes.

Oh for days when everything just fitted (apart from the weird one with the Italian thread obviously)


 
Posted : 16/04/2018 6:11 pm
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If it's HT2 type, then it'll need a 1mm spacer either side (presuming the centre tube fits).


 
Posted : 16/04/2018 6:14 pm
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okay...

Shimano MTB cups are slightly narrower than their road counterparts. The cups that is.

The MTB tube is wider though, as MTBs run spacers and road setups don't.

Hope (and others) cup width isn't any different though, just the central tube. I suspect the Rotor is the same, although I can't confirm it.

...and I have a Gradient too ... I actually prefer the Shimano MTB cups as it narrows the chainline a tad (Rotor cranks, XT BB)


 
Posted : 16/04/2018 6:36 pm
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ps. you can always leave off the central tube if it's too wide, as a MTB one will be with a road crank.


 
Posted : 16/04/2018 6:42 pm
 scud
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Thanks all


 
Posted : 16/04/2018 8:36 pm

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