For the burliest trails and most dedicated adrenaline junkies, a downhill mountain bike is a must. Downhill bikes discard all pretense for sheer speed. Don't bother trying to wallow up a hill with 200mm of suspension; DH bike trails are usually accessed by shuttle or lift. Models like the Trek Session, YT Tues, and Giant Glory race under the most fearless athletes on bikes. But hit your local resort in the summer and you'll see every kind of downhill rig imaginable.