MTB Bottom Bracket on a Road Bike

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  • MTB Bottom Bracket on a Road Bike
  • jota180
    Member

    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?

    TIA

    the meausrement of the cups is ever so slightly larger on mtb compared to that of road.

    a 1mm spacer on your xt cups would make them 3mm too wide

    jota180
    Member

    So you’re saying the MTB cups are 0.5mm wider on each side?

    sorry, 1mm wider per cup plus 2x 1mm spacers would make it 4mm too wide.

    jota180
    Member

    Bugger!!!

    you advice is the total opposite of this I found, now confused 😐

    http://www.bikeradar.com/forums/viewtopic.php?p=16135141

    andyl
    Member

    i was under the impression that road cups where slightly wider.

    jota180
    Member

    I guess some ‘suck it and see’ time will be required after all

    thanks for your help guys

    Premier Icon wool
    Subscriber

    Running Mtb bb on shimano compact cranks no problem just try it

    coatesy
    Member

    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).

    jota180
    Member

    Cheers for that – I’ll stick a spacer either side and see how it is

    jota180
    Member

    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 goes

    zerocool
    Member

    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.

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