I had a problem with a 1R, in fact. It won't grip well the bars (diameter to match that stem), unless tightening a lot the bolt. Any shim (even the Nitto one) would be already too much, so I made sure to grease well the bolt (to prevent stripping the threads) and used the carbon assembly that I use for the road bike (which has carbon seatpost and fork steerer), the Finish Line fiber-grip. It really works! Grips well and no creaks :)
Yeah, that's good!
I had a problem with a 1R, in fact. It won't grip well the bars (diameter to match that stem), unless tightening a lot the bolt. Any shim (even the Nitto one) would be already too much, so I made sure to grease well the bolt (to prevent stripping the threads) and used the carbon assembly that I use for the road bike (which has carbon seatpost and fork steerer), the Finish Line fiber-grip. It really works! Grips well and no creaks :)