Wanted to give an update on my switch over from Shimano M520 pedals to ATAC XS.

Firstly the difference is very subtle. If you are used to one for clipping in/out you may not even know the pedals were switched unless you are looking for it. More like the difference between new and old cleats.

When pedalling the ATACs feel a little more like there is a hard ball you foot is resting on, not in terms of a presssure point, but in terms of the ATACs require a bit better ankle control otherwise they let you splay your feet outward.

The clipping in out with ATACs feels a bit more gummy, a bit more sliding friction (not talking about spring resistance) This perhaps could be the difference between brass vs. steel cleat.

I have on a few occasions found that the ATACs can grab/hold the cleat, but you are not clipped in. But just like the Shimanos, they do give a click to indicate you are positively clicked in, so this is not an issue.

As to holding retention, the primary reasons I bought the ATACs over the Shimanos, this I have not tested yet.

Al