Three main forces are considered for this calculation: gravitational,\(F_{g}\); friction, \(F_{f}\); and drag, \(F_{d}\). In GTA, friction is disregarded, as it represents only a small fraction of the power; also, the losses, \(l\), mainly represented by the friction of the chain and other mechanical components of the bike, are negligible.
Obviously, the speed used in this equation has no relationship with the velocity used to update a particle’s position. Here, the speed is calculated through Eq. (7), representing the cyclist ascending or descending (vertical) speed, using two consecutive values of the cyclist’s objective function (OF ).