BBB used shims they made, molded with an anti rotation key to fit in a groove (shown) in the quill shaft , they are 1/16th thick ,
like the tube wall of the steerer tube so they are combined to be the same 1 " outside diameter.. 25.4mm


I have bought threadless stems , and they included the split shim to use that on a 1" threadless fork.

Otherwise, they should be available from where you get the stem ..



FYI .... 0.125 " is 1/8" _ 1.25" is one and a quarter inch _ 31.8 the metric equivalency. (31.75, to be more accurate)







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