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Quickie, can you run an XT Bottom Bracket (the external bearing jobbie) on a roadbike running Ultegra (needing the external BB) desperately trying to work out how to build up my sons Christmas present new grouppo with no Ultegra BB and all the shops are shut !!
HELP !
Thanks
give me 5 mins, i've got an ultegra bb on a roadie and an xt bb on the ntb, i'll go measure.
no, you can't do it because the xt ones got 'mountain' on it and the road one has 'road' on it! : )
seriuosly though, i can't see why not. i could'nt measure that accurately but both seemed about the same width (9mm'ish). slap it in and see what happens i'd say.
Pretty sure they're identical except that the XT threads in a bit further (ie. it's a longer/deeper component).
It will explode and you will die.
Aren't the road cups a bit narrower than the mtb equivalent? I think the axle on the ultegra crank may be shorter, so you may end up short on spline engagement.
one is narrower than the other so it shouldn't work.
edit: beaten to it!
Bugger !
Thanks lads !!
druidh - Member
they're identical except that the XT threads in a bit further (ie. it's a longer/deeper component).
You will have exactly the same amount of spline available.
Yes. I run a HT11 road bb on my HT.
The thread depth is a red herring.
Road BBs are for a 68mm shell and have no spacers.
MTB BBs use 1-3 spacers but it always add up to 75.5mm with the shell.
So, the cranksets are not interchangeable.
It is possible to find a combination that will work, but you may fit the wrong (too short) joining tube and let the crud in.
PaulD
I wouldnt use a road BB as the cups probably wont have enough thread engagedment in the MTB BB shell.