From Anarchonomicon:

Motorcycle are fast, nimble, and outstrip even tracked vehicles in off road capability. In the woods a bike can get between the trees right under the densest canopy and travel along single track trails no wider than what a person or deer might walk, and wind between and, for the skilled enduro rider, Over! massive rocks and terrain that would rip a tank apart. Bikes preform uniquely well in mud, while the dual-sport bikers reading this are probably shuttering at memories of wrestling their bike up after a fall or stall in waste deep water, or their feet slipping about while trying to keep their bike balanced upright as they try to turn around on a trail… A fit guy can individually wrestle his bike out of spots professional teams would struggle to recover any larger vehicle from. With others to lend you a hand recovering even a heavy bike becomes fairly trivial.