The cassette you use on your bike has a significant impact on your climbing ability and performance. With a larger low gear, you'll be able to climb steeper hills with ease. The Shimano Deore CS-M5100 11-Speed Cassette is designed for trail mountain biking. It is compatible with Shimano's HyperGlide freehub bodies and is available in both 11-51T and 11-42T options.