I need to replace the headset on my old trek 1.5 alpha 2011 model, and also my b'twin ultra 720AF will need the bearings replaced soonish.

Is there a reliable way to find out what headsets I need? I've had two close, but unsuccessful attempts at getting the right ones before. In the end I've had to give up and use my lbs, which is annoying as I have all the tools required to change these.

Any advice is most welcome.

  • 1
    blue.canecreek.com/headset-fit-finder for older bikes, but its certificate is currently expired.
    – mattnz
    Commented Feb 25, 2020 at 23:29
  • Also bottom bracket advice would be most welcome.. these things are so hard to identify...
    – John Hunt
    Commented Feb 26, 2020 at 8:13
  • According to the trek site (archive.trekbikes.com/us/en/2011/trek/15#/us/en/2011/trek/15/…), the trek has: > 1-1/8" semi-integrated, semi-cartridge bearings Unfortunately, I'm not sure what the SHIS standard is for this.. fortunately, I have a 1-1/8" headset lying around that I tried to fit to my b'twin which wasn't quite right, I'll try it in the Trek.
    – John Hunt
    Commented Feb 26, 2020 at 11:14
  • Hmm, managed to find the BB type for the b'twin here: decathlon.co.uk/ultra-cf-road-bike-frame-set-id_8500450.html - Pressfit 86, so that's a minor win. I ought to carve this info into the frame lol.
    – John Hunt
    Commented Feb 26, 2020 at 11:30
  • I called Decathlon (store for B'Twin bikes), they wouldn't help me other than "we can order you one, it costs £17.99"... unfortunately I think I'm going to have to do this and then just report back here lol.
    – John Hunt
    Commented Feb 28, 2020 at 14:50

1 Answer 1


I sent trek an email and they responded . They say the correct headset has article number 423140 and costs 29.99€

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