Shimano Pedaling Dynamics


Shimano Pedaling Dynamics, also known as SPD system, is a design of clipless bicycle pedals. The SPD pedal was released by Shimano in 1990. While not the first, its innovation is a small cleat which fits in a recess in the sole of a shoe designed for SPD use.
Shimano makes a number of different SPD cleats, and not all cleats are compatible with all pedals, especially between "road" and "mountain" SPD product lines. Among otherwise-compatible cleats, there is an important distinction between black "single release" cleats and silver "multi release" cleats. The former can only be released from the pedal by twisting the heel outwards, while the latter can also be released by a sharp pull upwards and are therefore easier to use for novices.
There is a small allen key adjustment for the strength of heel twist to release, so beginners can have it 'soft' and easy to get out, and then tighten it up as they progress.