This conversion set lets you use standard size handlebars with a smaller diameter in an oversized stem, solving fit issues without replacing components. Components - Handlebar stem reducer: enables installation of standard size handlebars with a smaller diameter into an oversized stem. - Bicycle handlebar washer stem adapter: lightweight CNC machined aluminum alloy, durable with high hardness, practical and resistant to deformation. - Saddle tube adapter: enables you to use standard size handlebars with a smaller diameter in an oversized stem. - Bicycle accessories: a professional and affordable washer for the bicycle handle, a robust tool that meets practical requirements. Benefits - Function: closes the gap between stem bore and bar diameter for secure, reliable clamping. - Compatibility: works with standard size handlebars and oversized stems, expanding your retrofit options. - Material and strength: lightweight aluminum alloy, CNC machined, durable and resistant to deformation. - Performance: maintains shape under load for consistent performance. Use scenarios - Upgrading an older bike with an oversized stem while retaining your current handlebars. - Retrofitting a bike for a different bar diameter without replacing the stem. - Stocking a shop or rental fleet with a versatile adapter set for quick cross bike compatibility.