I've got to order a new chain and sprockets for my bike (VTR250) and I'm after some info on chains. I've heard of 5120, 520, 420, 410 chains and whatnot - but what's the difference? Is there a discernible difference between chains? I'm after something of good quality and like everybody I'll take anything to get a "racier" feeling bike. But I don't want something that'll be rubbish in a few months.