Square Taper to Hollowtech II

ed1973
ed1973 Posts: 284
in MTB workshop & tech
So I’m sat twiddling my thumbs and need to get something for. (Idle hands and all that) so I’m going to jazz my lads bike up, eg 2x9 to 1x11. He currently has a Shimano crank with a square taper bb, can I simply remove this and put in a Hollowtech bb and crank?

Comments

  • ed1973
    ed1973 Posts: 284
    Edit
    I need something to do
  • mully79
    mully79 Posts: 904
    It should be straightforward if* you have the correct replacement.

    Check the chainline measurement before taking off the cranks.
    Dont assume a bb axle with a different interface will be the same length as the square taper axle.
  • ed1973
    ed1973 Posts: 284
    Cool thanks for this. I have the tools for the job so will check the measurements.
  • reaperactual
    reaperactual Posts: 1,185
    edited January 2022
    Yes simple with standard BSA threaded bb.

    While you've got your tools out you'll need to confirm bb shell width for fitting the relevant bb spacers.

    (Pre 12speed) Shimano cranks will have chainline stated on the spec. Non Boost is a shade under 49mm and Boost versions have a 53mm chainline.
  • ed1973
    ed1973 Posts: 284
    Awesome thanks just have to find the spacers for the bb I have in the ‘bit box’
  • MattFalle
    MattFalle Posts: 11,644
    why do ypu want to do it, out of interest (apart from being bored).
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • ed1973
    ed1973 Posts: 284
    I like the tinkering side of bikes and mine have all been tinkered with and the boy wants a decent set up as he’s getting into it.
  • ed1973
    ed1973 Posts: 284
    Hit a bit of a hurdle and stripped the thread on crank side trying to remove it. Had a look on YouTube and it seems I’m going to have to get the hammer out to try and whack it off unless anyone has any better solutions.
  • MattFalle
    MattFalle Posts: 11,644
    try a puller or angle grinder.

    former is simple, latter is drastic.

    are you sure this tinkering stuff is really up your street?
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • masjer
    masjer Posts: 2,663
    A blow torch or electric paint stipper gun will loosen it up. The aluminium crank arm will expand more than the steel axle. Keep the heat away from the frame.
  • reaperactual
    reaperactual Posts: 1,185
    edited January 2022
    Well, now you've got something that's gonna keep you busy. 😬

    I also stripped the thread trying to remove a Hollowtech II type R.F. crankset. I tried everything and was hammering at that B#tch for days, it would not budge a millimeter, still don't quite know why it was so stuck.

    Yes drastic but the angle grinder method will work and may end up being the only way to get it off?

    I got some very helpful advice and tips here:-

    https://forum.bikeradar.com/discussion/13116740/cranks-removal-what-to-do-now#latest

  • ed1973
    ed1973 Posts: 284
    Success! Due to being able to get at the tapered part of the bb, just a 10 min job with a decent hacksaw with new blade got it off.

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