Bicycle trainer comprising a seat, handlebars and rotatable pedals, and an electronically variable brake acting directly or indirectly on the rotatable pedals with a braking resistance that depends on a predetermined setting of a computer-controller, which predetermined setting is variable and depends on selected parameters to reflect simulated cycling conditions comprising at least one of a road, wind conditions and a cyclist, wherein the bicycle trainer excludes a flywheel and includes a variable-ratio transmission system and that the predetermined setting of the braking resistance also depends on a setting or change of setting of the variable-ratio transmission system so as to simulate a level of inertia or change of inertia as experienced by an outdoor cyclist when changing the variable-ratio transmission system.