I can't help but wonder if you are reaching too far or if the shifters are too big for your hands? I've never had a bike with grip shifters, but I had, for a little while, a scooter with a throttle that you had to turn, and brakes that you had to squeeze, kind of like a mt. bike. My hands are quite small and I found that especially with gloves on, and I was a bit chicken to ride it with no hand protection... that when I would squeeze the brake I would also be turning the throttle!!! A little scary to say the least and I had to be very, very careful.