|How is it that the torques cancel when you turn a bicycle?
During a turn, you lean the bicycle into the turn. For example, when you turn left, you lean the top of the bicycle toward the left. The result is that you (and the bicycle) experience two torques. First, the support force from the ground tries to rotate you one direction—it tries to make your head go left and your feet go right. Second, friction from the ground, which is making you and the bicycle accelerate toward the left as part of the turn, tries to rotate you in the opposite direction—it tries to make your head go right and your feet go left. These two torques will cancel one another if you are leaning just the right amount. As a result, the bicycle doesn't undergo angular acceleration and you don't tip over.