Shoes for cycling can loosely be broken down into mountain bike shoes and road bike shoes. However, what shoes you get will depend on whether you choose to use clipless pedals or if you want to use toe clips or regular pedals. When you choose clipless, you get great efficiency, but you limit your choices.
If you choose not to go clipless and use either toe clips or simply the pedal itself, you can use virtually any shoe you choose. However, using a stiff-soled shoe will help with energy transfer. Use cross-training shoes or, better yet, trail-running shoes, which are typically lightweight and have a stiff sole. Some of these shoes can also be bought with a Gore-Tex liner so that they are waterproof.
Road Bike Clipless
Shoes for road biking are typically lightweight and have an exposed cleat, making it hard to walk in them. The best road bike shoes have a carbon fiber sole for unmatched stiffness and support in a lightweight design. Road bike shoes are very sleek and aerodynamic. Some also incorporate the unique Boa lacing system, which uses a dial to tighten the laces equally over all the lace points.
Some designs for road biking are a hybrid between a sandal and a shoe, such as the Keen. Shimano, make or top clipless pedals, has its own line of popular shoes. Sidi makes several different models of road bike shoes that are compatible with most major clipless pedals.
Mountain Bike Clipless
Mountain bike shoes for clipless pedals usually have a recessed cleat and are not as stiff as road bike shoes, because mountain bikers may have to get off the bike and walk on steeper, rockier terrain. The rubber soles will have a tread pattern to aid with this. Mountain bike shoe design varies from sleek shoes that are similar to road bike shoes to shoes that look more like hiking shoes or trail running shoes. Sidi, Shimano, Keen and Pearl Izumi all make excellent shoes for mountain biking. Again, make sure that the shoes are compatible with your pedals. See how efficiently mud and debris are cleared from the sole and pedal when locking into the pedal.