Your tennis shoes are excellent multi-taskers. They can get you through a basketball game, a jog around the neighborhood and even an impromptu square dance. But if you plan on doing a lot of mountain biking, you'll need shoes that meet the unique demands of serious pedaling.
Mountain biking shoes have several qualities and components that separate them from regular athletic shoes. First of all, they're extremely lightweight. Since they're designed only for pedaling, they don't need all the support and cushioning that basketball or running shoes require. They're also light to save you energy. If you're already working hard to pedal up a steep, muddy hill, you don't want to expend extra effort just lifting your shoes.
Mountain biking shoes usually have a stiff, carbon polymer sole that maximizes the power transfer from your leg muscles to the pedals. The soles of high-end racing shoes have a high arch to keep the foot in ideal pedaling position.
Heel slippage is the biggest shoe-related problem while mountain biking. Slippage can cause serious blisters, take power away from your pedaling and just be plain annoying. Most mountain biking shoes are designed with a special molded plastic heel that adds extra anti-slipping support. Most shoes also have several fasteners (both lace and Velcro) to make sure that they fit snugly across the length of the shoe.
Most mountain biking shoes are in the $50 to $100 range, but high-end models can reach $300 a pair. The Shimano M310, for example, can be custom-fit by heating up the shoe to 200 degrees and molding it to the precise contours of your foot. It also includes a "ratchet" style strap at the top, similar to a ski boot, making for a super snug fit. The heel has a "cat's tongue" fabric insert that slips on easy, but is hard to slide off.
Higher-end mountain biking shoes also come with detachable cleats and spikes. Cleats allow riders to clip into their pedals, giving extra traction. And spikes can be screwed into the soles of a mountain biking shoe when it's time to hike the bike up muddy terrain.
Now that your feet are taken care of, let's look at hand protection while mountain biking.