Trek 810 Mountain Bike - $150.00 Great, used mountain bike. It’s an 18” (46cm) frame good for someone 5’7”-5’11”. I have probably only used it 15 times. Here’s what Trek says about this bike: Rugged steel frame, suspension forks, Bontrager tires and wheels, Shimano shifters and derailers. Everything works great. 820 is a great bike at an even better price, and it lets you explore off-road riding without the giant price tag that comes with higher-end mountain bikes. The high-volume mountain bike tires and suspension fork take the edge off rough roads and trails. Rack, fender, and kickstand mounts make it easy to accessorize, so your mountain bike can double as a rugged commuter.