SPD cleats keep turning in Northwave road conversion
I got some Northwave SPD race shoes (Sonic 2 I think) and converted them so that they could be used with SPD cleats (I like SPDs). This involved cutting a flap, removing an adapter and putting in the cleat plate. I've used a torque wrench to tighten the cleats to the recommended 7-8 Nm, but when I try them in the SPD pedals they do not come out very easily and rotate, making them unusable and dangerous. I've tried two different cleat plates (Shimano and Boardman). It's a bit annoying as when they rotate they damage the bottom of the shoe a bit. Any ideas what I'm doing wrong? or suggestions that I could try?