Surly's Hurdy Gurdy Chain Tensioner is a nifty device that allows for precise chain tensioning on a singlespeed or internally geared drivetrain. They are also useful on derailleur geared bikesh for keeping that rear wheel from slipping in the dropout under heavy pedaling loads. The Hurdy Gurdy is designed for the Surly Cross-Check’s semi-horizontal front-loading dropouts and will also work on many other similar dropouts.
Investment cast of stainless steel for durability and good looks. Its two axle holes allow for a wide variety of fore/aft wheel positions. It will work with standard QRs, bolted axles, and nutted axles up to 10mm.