- MTB Bottom Bracket on a Road Bike
Does anyone know what a road bike HTII bottom bracket measures total width? – ie the full width when the cups are in place on the bike?
I need to install some cranks first thing and all I have is a XT MTB BB
The cups will obviously screw in and I can just ditch the inner sleeve or cut it down a bit, reading elsewhere, someone is saying the the road cups are 1mm narrower [10mm Vs 11mm] so in theory a 1mm spacer each side should bring it all where it needs to be.
Can anyone save me the trial and error time in the morning?
TIAPosted 7 years ago
the meausrement of the cups is ever so slightly larger on mtb compared to that of road.Posted 7 years ago
a 1mm spacer on your xt cups would make them 3mm too widePosted 7 years ago
So you’re saying the MTB cups are 0.5mm wider on each side?Posted 7 years ago
sorry, 1mm wider per cup plus 2x 1mm spacers would make it 4mm too wide.Posted 7 years ago
you advice is the total opposite of this I found, now confused 😐
i was under the impression that road cups where slightly wider.Posted 7 years ago
I guess some ‘suck it and see’ time will be required after all
thanks for your help guysPosted 7 years ago
Running Mtb bb on shimano compact cranks no problem just try itPosted 7 years ago
Road cups are definitely wider, i’ve measured them just to satisfy my curiosity(think it was 1.5mm per cup in my fading memory).Posted 7 years ago
Cheers for that – I’ll stick a spacer either side and see how it isPosted 7 years ago
Just for the record and in case anyone else needs the info at some time
English thread Shimano road BB cups are 90mm wide when installed without any spacers in a road frame and the MTB cups are 88mm
I’ve just left it at 88mm and see how it goesPosted 7 years ago
I’ve done it a few times with no problems on our bikes over the years. Although at the moment I’m running a Truvativ MTB crankset on my road bike as needed easier gears for a weeks riding in the Alps and couldn’t afford a compact chainset and the original one was massive.Posted 7 years ago
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