These can often be an overlooked area of mountain bike clothing, but they are essential to help avoid blisters and protect your hands in the event of a fall.You'll often find the backs of the best cycling gloves are aerated for comfort, while the palms will be double layered leather for better protection.
There's nothing quite like splashing through muddy puddles during a downhill run on your mountain bike, but you'll enjoy it more if your mountain bike clothing keeps at least some of the elements off you.
You might think a standard set of waterproofs would be fine for cycling, but you'll be a lot more comfortable wearing mountain bike clothing that is specific for the job. Cycling waterproofs will be much lighter and more breathable than standard ones, and will still allow for complete freedom of movement.
The best waterproof mountain bike clothing folds and rolls down into a small light bag that can be stowed away in a backpack in case its needed. You'll want to travel light when you're mountain biking, and proper mountain bike clothing makes life a lot easier in this respect.
Finally, if you are likely to be out biking along dirt roads during the evening, you might want to invest in some reflective gear as well. Making sure you'll be seen is an integral part of all good mountain bike clothing.