What is the mountain biking discipline focused on descending steep trails?

The mountain biking discipline focused on descending steep trails is downhill mountain biking.

Downhill, commonly abbreviated DH, sends riders from the top of a steep course to the bottom as quickly as possible. Courses are rough and technical, often including jumps, drops, rock gardens, berms, roots and other obstacles. In races, riders usually start at intervals and are ranked by elapsed time rather than racing side by side for the entire run.

Downhill bicycles are built for stability and impact absorption rather than climbing. They commonly use front and rear suspension, strong frames, wide tyres, powerful disc brakes and a dual-crown front fork. Because these bikes are heavy and have gearing intended mainly for descending, riders often reach the start by ski lift, shuttle vehicle or other uplift system.

Downhill is not the same as enduro. Enduro races include timed descents but also require riders to climb between stages, making them longer and more varied. Cross-country emphasizes sustained pedalling over climbs and descents, while freeride focuses more on creative lines and aerial manoeuvres. Downhill racing instead prioritizes speed, control and technical precision on a dedicated descent.