SRAM EX1 XG-899 Cassette - 8 Speed 11-48t BlackSRAM EX1 XG 899 Cassette 8 Speed 11 48t Black. The 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. Machined from case hardened tool steel Cogs are designed to work specifically with inner and