The mountain-bike discipline that races from the top of a course to the bottom is downhill.
Downhill racing is a timed event in which riders start individually and descend a steep, technically demanding course. Courses commonly include jumps, drops, rock gardens, roots, berms and other obstacles. The fastest rider records the shortest time.
Downhill bicycles are designed for control and impact absorption rather than efficient climbing. They generally use long-travel suspension, powerful disc brakes, wide tyres and geometry suited to steep descents. Riders usually reach the start by shuttle, lift or another form of transport rather than pedalling the race course uphill.
Downhill differs from cross-country, which combines climbs and descents over a longer loop. It also differs from trials, where riders negotiate obstacles while prioritising balance and precision rather than completing a timed descent.