Downward force on a hill is m*g*sin(phi)

m is the mass of the object (rider+bike)
g is the gravitational acceleration on Earth (9.81 m/s^2, or 32.2 ft/s^2)
phi is the angle that the hill is inclined

MASS does matter!!!

If a bike slid down a hill (rather than rolling), then mass would cancel out of the equations, but rolling resistance is difference than kinetic friction.