Hey, ive only just changed to 18 - 15 on my limey, after running 18 - 16 for ages and was struggling to get any decent height backwheels or sidehops, so i put the 15t on thinking it would help, but to be honest i have noticed and difference. im running 175mm cranks, so if i were to get some 165mm mod cranks, surely this would help a bit? cheers, jake.