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I bought a new crank for my bike, when fitted tight the crank is stiff to turn as I think it is rubbing against the bottom bracket housing.

Any advice on what to do, have I bought the wrong crank?

  • Is it a square taper bottom bracket and crank? See https://www.sheldonbrown.com/bbtaper.html Looks like you may have put a JIS crankset on an ISO spindle. Unfortunately, you may have damaged the crankarms by deforming the taper in them. Commented Feb 14, 2019 at 10:40
  • They both looked to be a square tapered. I did not know about the difference between ISO and JIX. Will look into that, I am pretty sure I did not damage anything as I did not have to use any force. Will check in more detail and maybe get a different bottom bracket perhaps ? Commented Feb 14, 2019 at 10:49
  • I think what @AndrewHenle is getting at is that by using the wrong kind of crank for your BB's taper, the crankarms are riding too close to the BB cups and may be rubbing against them, creating the problem you describe. It's hard to tell from the photo, but there's usually some BB spindle showing between crankarm and cups
    – Adam Rice
    Commented Feb 14, 2019 at 18:32
  • @AdamRice The actual problem is different square taper types can have slightly different angles to the taper. If you torque what's likely a softer aluminum crank arm down on a slightly "off" hard steel bottom bracket spindle, you can deform the aluminum crank arm slightly. If that happens, even if you later put the crank arm onto the proper spindle, it might not seat properly because of the deformation, which means it will wiggle around just a bit with each pedal stroke. Each wiggle will deform it slightly more, which makes the wiggle that much worse. Commented Feb 17, 2019 at 16:29

1 Answer 1


The problem was embarrassingly having a JIX crank and an iso BB. Seemed to fit fine. You live and learn

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