A person is on a bicycle, there are several situations like the bike is at rest, accelerating,etc. The one I'm having most trouble with is when bike is in constant velocity. For the bike,I have gravity and force of person acting downward, normal force upward, force applied to the right and friction to the left. ON the person, gravity and force of bike on person is once again there. Horizontally, I know I need to have the friction of the bicycle, but what direction is the friction acting? And what is the force that balances out friction to achieve net force of zero? Thanks for you help.