| This article needs additional citations for verification.
Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (June 2009) </td>
</tr></table>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 was its small cleat which fitted in a recess in the sole of a shoe designed for SPD use. The shoe could be also used for walking whereas previous systems had a large protruding cleat. Clipless pedals use a system of cleat retention which is quite similar to that of a downhill ski binding. Generally, clipless pedals are seen to be safer than the older style of pedal/shoe integration using toeclips, toestraps and shoeplates due to ease of disengagement. 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 cleats ("single release") and silver cleats ("multi release"). 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, both so the spring tension can be maintained as it softens through use, and so beginners can have it 'soft' and easy to get out, and then tighten it up as they progress.nl:SPD-pedaal pl:Shimano Pedaling Dynamics