I`ve been reading all you`r posts and i never saw my combination of sprockets..when i got my bike (second hand), the bike was with 12ft and 36 rear sprockets. Now i need to chance the front but i can only with with 15...so, how will having 15/36 affect my bike? I`m really confused. I know that having bigger front sprocket will prolly boost my top speed, and lower my torque, but is going up from 12 to 15 a lot? Will that make some damage to the machine or something?