I've tried Thumb extentions too. They work with big hands, but not small hands. My wife will chew your ears off on this one!!

 

Awhile back my wife had surgery on her thumb. I needed to find an alternative throttle. I discovered a product called the "Handy Throttle". It adds twist throttle function to the existing thumb throttle and you can still use either twist or thumb. Costs $40. Wanted to try the twist without altering the thumb if I didn't like it.
After using it on my wife's quad--I converted my own Ozark to a twist and will never go back to the thumb throttle. Use to be hard to keep from accidentally punching the thumb throttle when climbing a boulder strewn river bed. Doesn't happen with the twist-- and my hand is completely around the grip making it more secure.

 

i have a twisty on my shee and love it makes the all day rides much more enjoyable. I did break both my wrists *the scaffoid bone right below the thumb* and the twists are easier on my thumbs than the thumb throttle. Ive been meaning to get one for my BF since i mow and plow for hours on end on it. Never heard of the Handy Throttle might have to look into that would hate to have a twisty freeze on me while plowing, although my twisty on my shee has never froze on me during the winter it doesnt see as much snow time as the BF does.

 

Some people like them, I personally hate them on quads. They are very hard to be fine with in the rough and tight areas. Unlike a bike where the machine leans with you, a quad makes for an awkward angle while turning with a twist throttle.

I think in a place like the dunes or desert where you are going to be on/off wide open all the time they are OK. But in woods and tight trails they can make for some scary moments where a light touch is in order.

My father who was a lifetime biker put one on his KFX700 and raved about it while on the fast open trails.... but then after two pretty good crashes because of the twisty he went back to the thumb.....

FWIW Motion Pro makes a thumb/twist combination setup. That would probably be worth looking at for someone looking to have the best of both....

 

I tried one on my old Honda ATV and didn't like it at all. Made it more difficult to handle the throttle in rough terrain.

Not that thumb throttles don't have their drawbacks. I've stabbed a thumb throttle in reverse too hard while standing up and pinned my leg against the thumb throttle. Couldn't get my weight back enough to release it quickly enough. The end result was full power reversal with the rear of the ATV deciding to leave the ground and then wedging itself frighteningly high up a tree trunk.

 

What about a trigger throttle. We run them on Jet Skis, for that app they work great. Anyone tried them on a quad?

 

twist works great as long as your used to it. One of the Motion Pro kits should fit right on there.