I took the washcloth off to measure the OEM grip. The thumb part is hard. On the right, the throttle ring is also hard, but it has a bigger diameter. On yours, is the thumb part cushioned?
No, those grips I use and linked to are hard rubber. Not hard like plastic, but very firm rubber and quite grippy, which I like. I don't press my thumbs against the grips, they just sort of hang underneath until called upon for a PAS shift, mid-loud bell on the left and the shifter or throttle thumb activator I added on the right.
The Fat Paws arrived. One photo shows the OEM left grip. The top is soft but thin. The bottom is hard rubber. Another photo shows my hand with the damaged joint marked. In riding, it could rest on the edge of the hard rubber when I reached for a control button with my thumb or when I applied the brake. Then a bump could cause the hard rubber to recoil against the joint.
Another photo shows a cross section of the Fat Paw. The hole is about 14mm, so it has to stretch around a 22mm bar. Easy with alcohol! There are no edges to hammer vulnerable parts of the hand. The outer layer may be a millimeter thick. It feels as soft as the top of the OEM grip. The rest of the foam is much stiffer. It feels solid until you press hard. It can absorb shock without feeling spongy. The last photo shows that it really isn't very fat.
I'm getting back into the habit of using the front brake.