It's called Mountain Biking!

Races these days are loosing touch with what mountain biking is. Some events are long in kilometers but lack the technical challenges that differentiate us with road riders. Many races I participate in are really fun but are more like a road race with a bit of dirt just to say it's a mountain bike race. One race that's a true MTB race is the Nimby Fifty, what it lacks in distance it makes up in gnarl. The steeps are steep, when you see three arrows pointing down, it's no joke. Many sections on the course are more suited for a downhill bike than a cross-country one. Here's a good write up from Pinkbike that sums it up nicely.

Two videos that give you a good idea of the terrain. The first one is a climb (done on a trials motorcycle) and the second one is the same climb and one of the many downhills (this time on a MTB) enjoy.