Countersteering (Pushing on the inside handlebar) is by far the most effective input from the rider to lean the bike. The only reason people lean off the bikes is to keep the bike more verticle, which yields more traction, which allows higher corner speed. Thats a bit more for advanced and track riding. Edit: Just remembered Twist of the Wrist 2 has a very informative scene about this very subject. Weighting a peg yielded hardly any turn, even body lean didn't do much.