I finally got around to removing some harder plastic-y grips on some sale carbon ski poles today. I thought others might like to know how easy it really was. This is not new information, just confirmation that it works.
I brought water to a rolling boil in an 8 quart pot and held the full grips completely underwater for around 3 1/2 – 4 minutes. I used a glove-style pot holder to twist the grip and it came off really easy. I shouldn't have been surprised that the adhesive would be that easy to dissolve/melt, but it was.
Now I just need to order those Gossamer Gear grips!
