Just bought a pair of Shimano WR42L roadshoes with SPD cleats for indoor cycling classes ($25 since the bike shop has decided not to sell shoes anymore! SCORE!). The guy at the shop installed the cleats, so I don't think there's an issue with that, but 2/3 different bikes I've tried using them on, won't let me clip in. Now, I'm new at the clip in shoe game, but with one of the bikes, I tried the studio's loaner shoe and was able to clip right in, so I don't think it's me. It feels like the cleat is going in, but isn't big enough to stay put. The shoe comes right out as soon as I start pedaling. I have very small feet (size 37 shoes). I've read elsewhere that small road shoes have a tighter sole radius, and that I might need to add a plastic shim. Has anyone else heard of this or experienced it personally?