When I first bought my bike, it needed a chain, so the genius that I am, I bought a DID chain. However, I dont remember the size. 无论如何,当我骑着自行车穿上轮胎时,技术人员说我将不得不比我想象的更早更换链条,因为我"我改变链条的同时没有改变链轮。" I didnt know you had to do that. Whoops! Anyway, I just wanted to know what the stock sprockets (front and rear) sizes are and what the chain is. 520? 530? I really have no idea. Thanks!