Hi friends I have a little doubt on the gear ratios of a bike like a mountain bike which have front sprockets also. It's clear that we get maximum RPM and min torque out of a bike when the chain is on smallest sprocket at the rear and largest at the front(highest gear ratio). But i read that when climbing hills bikers choose smallest sprocket at the front and largest on the rear in order to ride with constant effort. This is what i can't understand. Why would they choose smallest sprocket on front? Basically, my question is what is the need for small sprockets at front? Because while climbing hill we need more torque and so we should choose largest sprocket at rear that's ok but why smallest or smaller at front. Because choosing small sprocket at front will just reduce the rear wheel rpm but will have no effect on output torque. So it will give no help while climbing. If you say that the advantage is more torque at lower rpm then rethink that torque remains same only rpm of rear wheel reduces and if we just wanna lower the rpm we can pedal slowly. Torque at rear wheel depends only upon rear sprockets. Then what is need for small sprockets at front while climbing hills. Plz help me clear out this.