The cassette is (are) the sprockets on the rear wheel that the chain runs on. They wear as you pedal and as the chain stretches. They start out nicely machined and symmetrical and wear out over the miles becoming skinny and worn asymmetrically. ( looking like a shark's tooth) Then your chain starts skipping and jumping on the teeth, especially in your favorite gears under load. You need a new chain, cassette and possibly a new front chainring. iCycle can help you with that. Lots of replacement and upgrade cassettes in stock TODAY! 7sp, 8sp , 9 Sp, 10sp , 11sp, 12sp
