Shimano Zee M640 Rear Derailleur

Shimano ZEE M640 Rear Derailleur. Shimano Zee is a line of gravity components that are an ideal starting point for aggressive riders and racers. Think of Zee as the gateway gravity component line that allows riders to get on board with Shimano's gravity program and experience premium new component technologies. The Shimano ZEE M640 Rear Derailleur Shadow design allows for a low profile body and bracket to avoid chainstay and obstacle contact. Shimano added a stabilizer switch to reduce chain drop and slap and the Top Normal return spring optimized for RapidFire shifters. The short cage version allows you to run a 28T max cog for faster riding with fewer big jumps between gears, while the long cage version accommodates up to a 36T max cog, which gives you a higher cadence and the ability to spin up hills.