It used to be that snow and sand were about the only things that could stop you from getting your adrenaline fin on a mountain bike. Now, Ktrak wants to let you conquer even those surfaces with their Rear-Drive Kit, â€œa universal attachment that replaces the rear wheel with a track drive system. It is designed to create traction on previously ‘unridable’ surfaces, such as show and sandâ€. Basically a set of tank treads for your bike, it gives you traction where other wheels would only manage to sink in and slip around. Plus, it makes your bike look really freaking cool. Get yours January 2007.