It's no coincidence that the long trousers favoured for tough downhill and freeride use are very similar to those worn by motocross pros. These robust trousers have to meet very similar requirements. Bike trousers for aggressive rides offer protection and durability before breathability. Since in the majority of cases these trousers are worn in the bike park rather than to cover actual distances, seated comfort also plays a minor role. Instead, padding is usually integrated at the knees. They're designed with freedom of movement that's ideal for stunts and big jumps and a surface robust enough to literally save the rider's skin in case of a fall. The typical motocross look just adds extra style points!