I've never understood why you throttle a motorcycle by twisting the handle. It's not a particularly comfortable or natural motion, and it's relatively easy for external factors (shifting in your seat, a bump, etc.) to affect the amount of gas you're giving the bike.
Seems like it would be a lot better to map the throttle to a thumb trigger, like on a jet ski.
Edit: also, I just remembered those various videos we've all seen at one time or another where someone is riding a motorcycle at low speed, loses his/her balance, and can only manage to hang onto the bike by the right grip. That's a moment when you really don't want the throttle mapped to the grip.
it's relatively easy for external factors (shifting in your seat, a bump, etc.) to affect the amount of gas you're giving the bike.
Seems like it would be a lot better to map the throttle to a thumb trigger, like on a jet ski.
Those two statements seem to conflict IMO. There is usually less play in a thumb throttle, so external factors are more likely to have a larger influence than they would on a twist grip.
A thumb throttle is also more likely to accidentally slip to 0% than a full handlebar. With motorcycles, suddenly losing all power can be just as if not more dangerous than too much power. If you're not prepared, the rear wheel can lock up and cause you to lose control of the bike. It's very dangerous because you lose all steering, and if the tire engages while they aren't lined up with the direction of travel, the bike will flip, usually throwing you in front of it.
Like other things, you get used to it. It's probably more comfortable, and for a new rider it can be difficult to get your head around 'gripping harder will probably make you go faster, not slow you down'. Shifting in your seat/going over a bump shouldn't really affect it though, can't say I've ever noticed it happen while riding.
Snowmobiles work like that, too. My guess is that not having your thumb gripping the bars makes the handlebar grip much less secure, especially since you're not really gripping the throttle with your full fingers since two of them typically are covering the brake.
But it does definitely give you wrist cramp on long rides...
On powerful bikes, just a few millimetres of grip twist provides a huge amount of accelleration/decelleration. It's not the big kind of twist that you do with a boat outboard engine, but a small movement. I can't think of any time in all my bike riding when I've inadvertently 'given it the nuts'.
There's something particularly Teutonic about that thing with the turn signal switches. It's the same with how Mercedes always try and keep their car switches and buttons in the same position, and with the same design.
I suppose the psychology is, we make the best machines, so why would you ever want to buy anything else. If you only ever drove a Merc or a Beemer, why would it bother you?
