The Shimano 50, 51 & 55 are made for standard recessed-mounting shoes (ones you can walk in). The
'50 has zero float, the '51 (most popular) has moderate float, and the '55 is the multi-release
version that allows you to get out by twisting your foot in multiple planes (not at once!). For most
people I consider the '55 to be dangerous, because it can release unexpectedly when people stand up
to climb etc. Many have no problem, but some definitely do.
The '52 cleat was made for a specific pedal, the ill-fated 858 if I recall correctly. That
particular pedal didn't work with the other SPD cleats, but the '52 cleat was backward-compatible
with the other pedals.
Then you get into the '70 & '71 cleats, which are used with non-recessed (racing-style) shoes, with
the '70 being fixed and the '71 having rotational float. These cleats are a bit more expensive and
easily spotted because they have pontoons coming out from the sides.
--Mike-- Chain Reaction Bicycles www.ChainReaction.com
"Robert Strickland" <
[email protected]> wrote in message
news:[email protected]...
> What are the differences between the various grades of Shimano SPD cleats (SH-51, SH-55, etc.)?
> Are they all compatible with the various SPD pedals
or
> do some pedals only accept certain cleats?
>
> Rob Strickland