replacing SIDI buckles
I obtained repacement buckles for my nine year old Sidi Megas (one buckle was damaged in an accident).
The buckles are more compact now, and I discovered that the original caliper strap was now too wide to fit into the new buckle.
I checked the SIDI website and they advise to replace the strap (part SID0021) whenever you change the buckles (The straps are made to be compatible with older model shoes).
Therefore, if you are going to buy new buckles, make sure to get new straps.
BTW it worked fine for me.