Had a problem taking the MSF class with my left hand going numb but thought it was just from having to hold in the clutch so much. I still think that might be the reason as my hand was really sore after the class. Well today I was riding my Sportster and damn.....my left hand goes numb. It is really my thumb going numb and not the whole hand. It has been suggested to try gel gloves or different grips to stop the vibration. Now my question is......wouldn't my whole hand go numb if it was the vibration? Why would just my thumb go numb. Guess I'm asking if any of you guys experienced this and what did you do to fix it.