A bicycle at rest or in uniform motion in a straight line will continue in that state of rest or uniform motion in a straight line, unless acted upon by a headwind or an extreme gradient.
A bicycle being pedalled normally along a level road will accelerate until it reaches a speed limited either by the rider's abruptly waking up to the awful consequences of coming off his machine at the next corner, or by the bumpiness of the surface.
Every carefree descent leads to a far more agonising knee-grinding ascent.
There ought to be one about the consequences of getting stuck in a herd of cows that are being driven in to milking along a very narrow country lane.