Good debate goin here...
I can talk from experience from both aspects here.
I have recently baught my z400 and I instantly chanced my thumb to twist due to for racing and my kind of riding I need(??) twist. But after 3 races 1 of my acidents and the second is debatable, is due to the twist throttle.
If the rider hits an unexpected bump or set them self up wrong on the seat they may pull back on the throttle to correct them self and this can get them in to big trouble... I still love it though and I feel I have more control with this setup due to my thumb position on the handle bar. Dont quote me on this as I am still on my ''L'' plates as it comes to racing quads.

Gareth...

 

im 13 and i just got a 1992 yamaha yz125 ditbike on july 3 2004. and ive been on a 4-wheeler sence i was 6. i have a blaster and a kodiak. ive riden a dirtbike before for maybe about a hr total in my life. it was fun the only thing i didnt like was the throtle i wiped out and when i fell over i was hanging on and i didnt let the throttle out so it just keep sliding on the ground. so after about an hr of driving the one i just bought i asked my dad if he knew if u could put a thumb throtle on. cause i hated the twist

 

I would give anything to be able to ride a bike again but my wrist will not let me use a twist. Since owning my quad I have fallen in love with the thumb throttle, better control and quicker WO response. The thumb IMO allows you to relex more on the bars.

 

I feel the same way about what was said about the physical difference between bikes and quads and how you handle them. Bikes (motocross bikes) have totally different ergonomics than quads and were designed to be ridden primarily standing up. The distance between the bars and pegs on a quad is much closer than a bike, placing your body in an exagerated slumping position when standing. For me, it's even more pronounced because I am 6' 6". Taller bars can rectify some of it, but it just comes down to the fact that the majority of quad buyers sit down 90% of the time when they are riding. Therefor, quads are designed around the idea that the rider will be seated for the majority of the time. As far as the thought that your wrist ends up in an akward position with a twist, that's because you are gripping the bars incorrectly. Not one pro in the world walks up and grabs their bars with a ham-fisted, straight-on grip. All of them hold it like a tennis racket and grab ahold of it in a forward position, ensuring that at WOT, their wrist and forearm are in a straight line. This type of grip also forces you to keep your elbows up. There are advantages to each type of throttle, but they are only relative to the end user. What works for one person may not work for another. No two people in the world see things exactly the same way, so preference really is the only reason why they are used.


As far as my preferences, I couldn't ride a bike with a thumb, and I won't ride a quad with a twist.

 

Twist...I have to have ALL my fingers wrapped around the bars. Hittin' bumps with the thumber had me launching into trees when traveling at a fast clip along rough trails.

 

i have been told that with a twist u would have more control... for example when riding, you can go from flooring your quad to your desired throttle by pulling back up with the twist...with a thumb u would have to wait for the throttle to come back. like i said with the twist you can go faster or slower by moving the twist to your desired position. its just a differant feeling thats all.

 

well, me and my friend are both really good riders, and he has a few quads, but now he's got his lt250r set up for trails and he has a twist on it. It's really hard for him to keep up with me in the trails because the twist throttle is more touchy and it's harder to handle in tight trails.

 

how can you get a sturdier grip with a thumb throttle, when your thumb is on the throttle, where as with my twist my thumb is wrapped
around the grip

 

because with your whole hand on the twist, it twists around the handlebar

 

This may be a little deviation from the twist/thumb debate, but maybe it's a lot like game controllers. My buddies all use the analog mode, whereas I have to use the regular buttons.