Say I wanted to attach a dynamo up to some pedals or something - what factors would affect how hard the shaft would be to turn? Is it governed by the physical configuration of the dynamo (windings, etc)? Or is it the (electrical) load attached that matters - and how does that work? If I wanted to be able to alter the resistance (as in physical difficulty) of the pedals up and down in steps, how could I do that? What kind of steps could I get? And how would that affect the power/voltage/current/physical-electrons-coming-out-of-the-dynamo? I feel like I know a lot of terms and 'theory', but I have very little instinct for how things go together in practice.