For bikes that use a freewheel instead of a cassette, the microSHIFT M26C is specifically designed to accommodate the 13t cog that is commonly found on the small end of a freewheels' range. Shifting will be much improved with this model versus a conventional derailleur not designed for use with a freewheel. Features-Robust composite and steel construction-Compatible with Shimano 7- and 8-speed mountain and road freewheel systemsItem Specifications-Cage Length:Short-Chain Wrap Capacity (teeth):39-Color:Black-Drivetrain Speeds:7,8-Largest Cog:34-Rear Der/Shifter Compatibility:Shimano Mountain-Rear Derailleur Mount Type:10x1 Standard