It's a crucial part of a bicycle's drivetrain, transferring motion (and energy) from the legs, via the crank, to the driven wheel. It's also one of three bicycle components in constant contact with the rider's body, and therefore crucial for riding comfort and safety. Pedals consist of an axle, bearings, and a housing. In their basic version, a bicycle pedal is a flat element (platform) made of plastic or metal (usually aluminum) connected to a short, bearing-mounted shaft that attaches to the crank. The most common pedals consist of a platform and a movable shaft. In the cheapest versions, the platform is made of plastic. Platforms made of aluminum and steel often have serrations or a grater to prevent slipping of the shoes. The main limitation of these pedals is the low efficiency of energy transmission – they are transmitted solely through pressure (this covers approximately 45% of the leg movement phase). The obvious advantage of these pedals is the ability to be used without specialized shoes. Before clipless pedals appeared on the market, attempts were made to reduce the limitations of platform pedals by using toe clips (with or without straps). Clipless pedals, as the name suggests, feature a special clip mechanism that permanently connects the shoes to the pedals. The connection is achieved by grasping and snapping a cleat attached to the shoe. With practice, clipping into the clip occurs almost automatically when the foot is pressed on the pedal. Releasing the foot requires developing a twisting reflex. Clipless pedals "hold the shoe more effectively than toe clips, and the shoes should automatically release from them in the event of a fall." Currently, more than a dozen types of clip mechanisms are available on the market. The most common solutions are:
SPD - That is Shimano Pedaling Dynamics – a clipless mechanism originally designed exclusively for mountain bikes. The SPD system is almost as popular on mountain bikes as the Look system is on road bikes. There are also proponents of this standard for road bikes.
KEYWIN "This company's cleats were the first of their kind in the world. The pedal-to-cleat connection is incredibly strong and effective. This type of road pedal has now become the norm in competitive cycling."
LOOK – Pedals of this standard are very similar in structure to Keywin pedals but are much more common on the market. LOOK also produces clipless pedals that are direct competitors to SPD, i.e. MTB LOOK –they are slightly more resistant to dirt than SPD, but are not as widespread as the Shiman solution
Less common solutions come from companies Crank Brothers and Time .
