I ride bike trials and have gotten good at keeping a straight line. On a good day I can ride along the top of a handrail. To keep a bike going straight at low

I ride bike trials and have gotten good at keeping a straight line. On a good day I can ride along the top of a handrail. To keep a bike going straight at low speeds, you shift your weight, and by that I mean you swing your elbows or you knees, not your whole body. You also can vary the sensitivity of the steering input by controlling how much of your weight is over the front wheel. You can also use the front brake if you are deviating from your line. It allows you to push against the resistance generated to realign your center of mass.