I bought brake levers meant for 31.8mm handlebars (namely Tektro RL721, meant for cyclocross) some weeks ago, meaning to use them for a bike build which has a 20-something millimeter bullhorn handlebar.

Naturally, I didn't notice the error until now, when I am actually building it.

It's too late to return them, and they're perfectly good brakes, so I was thinking to find a way to use them. Is it possible to pad/shim this difference in diameter safely/reliably?

If so, what kind of padding would be best to use? I assume something like a metal cylinder with a fitting inner/outer radius, but not sure what such things are usually used for and where to find one.

  • 3
    The Tektro RL721 are in-line additional brake levers, they don’t work as stand-alone brake levers. They don’t have a receptacle for the cylinder on the end of a brake cable. Are you aware of that?
    – Michael
    Commented Oct 4, 2022 at 15:20
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    I was not! I really should have a bit more reseach on these. Or maybe the info on the product page is supposed to be clearer. Haven't found a single photo of them installed on a handlebar.
    – goose_lake
    Commented Oct 5, 2022 at 13:59

1 Answer 1


I have 3dprinted bushings in the past for non-critical items like lights and other accessories.

However brakes are safety-critical, and experience high-leverage.

I'd suggest printing up this starter, and use the clamp of the brake lever to hold it in place. If you're happy with that, then explore how to get the same basic shape in metal, probably aluminium. You might choose to offset the center hole a little to suit your hand and lever combination.


enter image description here

  • 1
    OK, thanks for the advice. Was also assuming that it wouldn't be so safe, I guess after all I should just try to look for another set of brake levers.
    – goose_lake
    Commented Oct 5, 2022 at 14:00

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