Mountain bikes are designed to be ridden over rugged terrain and technical trails with logs, rocks, roots and other obstacles. They have a sharp frame geometry that puts the rider in a commanding position to pedal and climb efficiently. They have lower gear ratios that allow riders to pedal through steep and difficult terrain. Because of their intended use, mountain bikes are sturdy and overbuilt to handle the abuse of the trails. They usually have larger, heavily knobbed tires and strong brakes like hydraulic disc brakes. Many mountain bikes feature a kind of suspension shock over the front tire or both front and rear, allowing the frame to comply with the bumps, jumps and challenges of the trail.