When choosing a new chain and sprockets for your scoot, there are a number of things to take into consideration. A popular modification for racers is to replace a stock machine's 530 chain with a thinner and lighter 520 series chain and matching sprockets. Generally, roller chain is denoted as follows: the first digit specifies the chain's pitch, in 1_8 inch increments. The remaining digits correspond to the width of the chain in 1_80 of an inch. A 530 chain, then, has a pitch of 5_8 inch, and a width of 30_80 inch, or 3_8 inch. A 520 chain is 1_4 inch wide, correspondingly lighter, but also somewhat weaker than a 530 chain. There are some exceptions to this; For instance, 125GP machines utilize a 428 chain, which is a 425-sized chain with slightly thicker sideplates. Front sprockets are usually steel, but rear sprockets are available in either steel-which is somewhat heavy but lasts a long time-or aluminum (lighter, but less wear resistant).