Ritchey Stem Shim Adapter The Right Stem for the Fork You Already Have Mismatched steerer and stem clamp diameters are one of those fit problems that can hold a build back or keep a perfectly good fork on the shelf. The Stem Shim Adapter solves that with a simple alloy shim that bridges the gap between what you have and what you want to run. It handles two common conversions: a 25. 4mm steerer up to a 28. 6mm stem, or a 28. 6mm steerer up to a 31. 8mm stem. Whether you're building up a classic steel fork with a modern stem or sorting out a parts-bin build, this is the piece that makes it work. Features25. 4mm to 28. 6mm conversion lets 1" steerer forks run a standard 1-1/8" stem clamp28. 6mm to 31. 8mm conversion lets 1-1/8" steerer forks run a 1-1/4" stem clamp Alloy construction durable and lightweight for a fit-critical component Genuine Ritchey part engineered to pair correctly with Ritchey stems and maintain a secure, properly torqued interface | Ritchey | Stem Shim Adapter 28. 6 To 25. 4Mm, 1-1/8" To 1"