Cup/cone to square taper BB.

Eddy32
Eddy32 Posts: 18
edited July 2016 in MTB workshop & tech
Might be a simple question but,

If a cup and cone spindle measures 120mm, is there/it possible to use a 118mm BB with spacers 1mm on each side?
Someone with the same bike said "122.5mm was to big".

It's a cheap bike and uses a 120mm cup/cone BB, and a "prowheel jazz" crankset, the crankset is bent and the bearings are clicking/crunching while peadling.

I would like to replace it with a shimano un55 63x118mm BB?/ Shimano Acera M361 crankset.

Is this possible/ any ideas?

Comments

  • The Rookie
    The Rookie Posts: 27,812
    To can't use spacers, no.

    You need the axle to go with the new crankset, what axle worked with the old one is irrelevant as they have different offsets of the rings from the mounting on the axle.

    Check the specs for that Acera crankset but it almost certainly will want a 122/3mm being Shimano.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Eddy32
    Eddy32 Posts: 18
    So if replacing the crank with the Acera M361 lists "Spindle Length: 122.5mm".
    Would make the old/current BB 120mm spindle length irrelevant?
    Other words buying the Replacement Crank with Spindle Length: 122.5mm would mean I also buy a 122.5 BB, and the chain line should be fine?

    Thank you for your time.
  • cooldad
    cooldad Posts: 32,599
    Yep, axle length has to match the new crankset.
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  • Eddy32
    Eddy32 Posts: 18
    cooldad wrote:
    Yep, axle length has to match the new crankset.
    Thank you.

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