Ahead Stem Shim 25.4mm To 28.6mm 90mm Long. Ahead Stem Shim 25.4mm To 28.6mm 90mm Long. Allows The Use Of 1-1/8 Stem On 1" Steerer Tube. We carry over 3,000 bicycle parts and accessories. If you have any questions about any of our parts, please send us an email.