As a note 51’s and 52’s are single release and 55’s and 56’s are multi release. that only thing different about the is the release route offered..
multi release cleats are terrible – who uses them? and they really do not have any more ‘float’ that single release… though they do release in loads of different positions (mainly when you don’t what to!)
also rotation on spd increases over time (sic) as they wear… I find left ones wear most as that is the foot I put down
OK were splitting hairs here on what we define at float but essentially allows your heel to move laterally?
It seems to be… though as above you can do this with atac’s – heel in and out laterally but with the cleat rotating on the pedal, but also with atac you can also move you who foot laterally i.e. the cleat can move laterally in relation to the pedal.
it is this latter feature that i think helps with their comfort.
the most comfortable SPDs were the original double spring XT ones