The cyclist uses steering and body movements to control the lean of his bicycle. This lean (i.e., the deviation from the vertical position) is important both when driving straight ahead and when taking a turn:
- When riding straight ahead, the lean must remain small, otherwise people will swing too much from left to right.
- When cornering, the correct lean angle must be chosen, appropriate to the bicycle’s speed and the sharpness of the turn.
A cyclist can control the lean of his bicycle in two ways:
- By changing the position of the handlebar, for which he uses his arms.
- By changing his trunk and lower body.
We already discussed the role of steering impulses when cornering on the page about countersteering. The role of steering impulses in riding straight-ahead is based on the same physical principle, but the rider’s goal is different. Specifically, if the bicycle leans to the left (right), the rider can correct this by applying a pressure on the handlebars in the same direction: by applying a pressure to the left (right), the bicycle leans to the other side. By dosing the pressure on the handlebars, the bicycle can be set exactly upright. Often, only a little pressure is required to set the bicycle upright, and therefore it is not always necessary that the front wheel is visibly turned.
Besides the handlebars, the cyclist can also use his trunk and lower body to keep his bicycle upright. It is thanks to this fact that, with some practice, we can cycle no-handed. However, we do not know the precise stabilising movements of the trunk and the lower body. It is often said that a bicycle can be leaned by shifting the center of mass to the left or the right, which is possible by moving the upper body in the same direction. By moving the upper body away from the lean, gravity would bring the bicycle upright. However, this way of leaning the bicycle is much slower than by pressing on the handlebars. If you want to quickly put your bicycle upright, you have to quickly and accurately press on your handlebars in the direction of the lean.