Shimano UN26 question

jbwilliamz Posts: 187
edited October 2011 in Workshop
Hi guys,

This potentially could be a very dull question.

I'm in the process of building up a winter hack. I've got an old Orbea Asphalt (Mente) frame with a Shimano UN26 bottom bracket. Basically, is the frame limited to this BB? Or could I put an external bearing BB (or any other for that matter) on it?



  • BB's can be confusing but all you need to know is whether it's an English or Italian BB, it should say the width on the old BB shell. If it's 68mm then it's an English thread.
    You won't be able to use BB30 Bottom Brackets but otherwise all should fit.
    If you want to move away from the square taper type bottom bracket then you'll also need to change the crankset. Could get expensive !
    I recently changed a UN26 for Shimano Hollowtech BB with no problems .
    There's warp speed - then there's Storck Speed
  • Cheers!

    I've got a spare Shimano 105 chainset, so was hoping to get that on there.

    In terms of measureing the BB Shell, am I right in thinking I can just turn the bike upside down and measure the BB shell in that way?
  • Pseudonym
    Pseudonym Posts: 1,032
    68 is the shell width, so flipping it and measuring the BB will probably give you the answer, although I doubt if the width will be exact....
  • StorckSpeed
    StorckSpeed Posts: 291
    edited October 2011
    You can definitely measure the bottom of the BB with the bike turned upside down and this should be OK. 68mm for an English thread, 73mm for Italian.
    If you remove the UN26 BB from the bike there's some writing on it.
    Usually something like 68 - 110mm.
    68 refers to whether it's English or Italian, 110mm is the overall width, including taper arms.
    Shimano 105 with Hollowtech BB shells will be great and will run perfectly.
    There's warp speed - then there's Storck Speed
  • Cheers guys!