>Use of stored energy is obviously allowed or else you couldn't make use of gravity when on a hill.

You've walked past gold in search of silver. A biking competition that disallowed the use of gravity would be wild. What would that even look like? How could it be run? Compressed air jets to maneuver bikes onto friction platforms? Entire courses built into the non-rotating sections of space stations? Racers suspended on bungee cords to counteract natural forces?