A good mountain bike jersey is a crucial, but sometimes overlooked, piece of mountain biking gear. A quality jersey is designed to wick sweat away and to keep the rider dry and cool, unless of course it's a cold weather jersey.
During the summer time, many cross country, trail riders, all mountain riders, and enduro riders utilize jerseys with the standard three pocket design. These three rear pockets allow riders to stow gear that they need to be able to access quickly and easily. Many of these jerseys feature either a full-length zipper or a three-quarter-length zipper.
Many freeride mountain bikers and downhill mountain bikers wear baggy jerseys. These jerseys are still usually made of synthetic, sweat-wicking materials, but they are baggy enough to allow the rider to wear protective padding underneath the jersey.
In the wintertime, many riders wear warm, thermal long sleeve jerseys. These jerseys are very warm, but are also very breathable, unlike some mountain biking jackets. Many winter jerseys also feature the standard rear three pockets for easy gear storage and access.