• Reviving this rather than creating a new thread but has anyone tried shimming a 1" (25.4mm) steerer for a 1 1/4 (31.8mm) stem? I know that 1"-1 1/8 exists so surely you can do the same just with a thicker shim to accommodate the stem?

    I spoke to a mechanic who was very unkeen on the idea but I've got a stem and bar combo I had planned to use and would quite like to stick with...

  • As steerer shims are single piece slotted, the problem is going to be compressing the shim in order to clamp everything up.

    28.6mm (1 1/8”) - 25.4mm (1”) is a difference of 3.2 so shim wall thickness will be 1.6mm.

    At 31.8mm - 25.4mm the difference is doubled to 6.4mm so shim wall thickness would be 3.2mm.

    You may exceed the torque rating of the stem before you reach a satisfactory clamping force.

    As shims to do the job don’t actually (afaik) exist and you’ll be having to make/have one made then you could go for a two piece design but poor alignment of the pieces may cause issues.


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