Choosing the correct rear cassette defines your bike's gearing ratio's, which in turn define how your bike will perform. Larger sprockets equate to lower gears, and sprocket size changes here have a considerably greater effect on resulting gear inches that similar changes to front chain ring size. For example, a 2-teeth increase in maximum sprocket size on your cassette will have a profoundly greater effect than a 2-teeth reduction in chain ring size. Due to these physics, along with the fact that chains have become narrower; many riders nowadays are preferring a 2x10, or even single chain ring set-ups; relying on the super-wide ratios offered by today's cassette designs. We stock Shimano and SRAM cassettes at internet-beating prices, making essential regular cassette replacement less painful, and more fun.