Bike riding is one of those sports that anyone can enjoy and the benefits are almost limitless. The motivations for cycling vary, from just wanting to get a bit of fresh air, to wanting to dramatically enhance your fitness. Generally speaking the type of cycling you do will affect how your muscles will adapt. If you cycle very long distances at relatively low intensity, your muscles will become very good at endurance and will build many slow-twitch fibres. On the other hand, if you cycle hard and fast, your muscles will build fast-twitch fibers and become more powerful. So which muscles get worked the hardest when you ride a bike.
Quadriceps (thigh muscles). Without doubt the muscles that produce most of the force when cycling are the quadriceps. These muscles work to extend the knee joint and provide a downward force on the pedals, which is then passed onto the crank. Racing bikes in fact are designed to locate the quads directly over the crack so that maximum efficiency is achieved. When travelling at speed the quadriceps contract and relax at an incredible rate and a great deal is demanded of them.
Gastrocnemius (calf muscles). The calf muscle is a great deal smaller than the quads, but no less important when it comes to propelling the bike forwards. Flexing the calf muscles when the leg is in a straight position, points the toes towards and adds a small boost to the overall power output. Pinarello make pedals that dynamically pivot to squeeze every last bit of power juice from the calf muscles.
Hamstrings. After the quads have forced the leg down and helped move the bike forwards, the hamstrings work to to pull it back up again and reset the leg ready for another push. This doesnt require much force on a standard bike as the rotation of the pedals pushes the leg up but when you use cycling shoes that clip to the pedals, a large amount of additional force can be generated by these muscles in the upward movement