Sram xg 899 e block mtb cassettesrams xg 899 e block mtb cassette is part of the new ex1 ebike specific drivetrain and has been specifically designed for the extra torque and demands of electric mtb bikes the xg 899 features larger steps between the sprockets which is a completely new technology that has been designed to optimise the power output of your electric off road bike the individual cogs architecture has been engineered to work with the chains inner and outer links giving you extrem