SRAM EX1 Rear Derailleur - 8 Speed, Long Cage, BlackThe EX1 drive train was designed specifically for the demands of electric assist mountain bikes: a wide gear range with bigger jumps between gears and sturdy components to handle higher torque loads. Liberal use of features found on SRAMs high end MTB parts provide high value, quiet operation and ease of service. X Horizon design minimizes chain slap, maximizes 1x drive train performance Engineered for high torque, low cadence E bike operation Product