Shade-tree mechanics use hair spray, glue, gorilla snot, friction tape, and special adhesive to put on new grips. We just use more contact cleaner. Spray it into a new grip, liberally coating all the inside surfaces. Give it a really good shot, a couple of seconds’ worth. Then immediately slide the grip on to the bar end. Then walk away for 20 minutes and let the tacky rubber bond to the bar end.