Mountain Biking - automatic transmission?

I was talking to a friend about whether or not anyone had build an automatic bike, and I figured somone had to have done it, so I did a little looking and found this.
http://www.grisleybicycles.com/technology.html
Anyone ever seen this? It sounds kind of cool, Its available with a max of 12 speeds, but I would asume they could make a 27 speed one if they wanted to. Not sure how it would work on a mountain bike though. Just thought it was kind of interesting. Perhaps worth a discussion on fesability.

someone who took my EE100 class a few terms ago made an automatic transmission for a bicycle for the final project. i never saw the actual piece but the professor said it was neat but it was a heavy box..

I saw some infomircial with an automatic bike and thought it looked like a POS, the comercial was hilarious though they made changing gears sound like an impossible task and it should the automatic bike smoking a road bike up a hill, and it could be all yours for just 4 easy payments of 99.95 stupid Sunday morning tv.

There have been several "automatic shifters" over the last several years, but they all boil down to one, clear, fact: they are heavy, slow and less efficient than standard shifters.

It is kind of pointless to have automatic shifting on a bicycle. What gear does it know to be in, the 1-1 combo? I don't use a granny gear on anyof my bikes, I think if I tried one, the auto shifting would screw my cadence/technique up.

Originally posted by danka24
It is kind of pointless to have automatic shifting on a bicycle. What gear does it know to be in, the 1-1 combo? I don't use a granny gear on anyof my bikes, I think if I tried one, the auto shifting would screw my cadence/technique up.

Its based on your rpms...when your rpms slow to a certain speed it shifts for you. (or when your rpms get to a certain spd)...

Giant offered a four speed(internal hub) cruiser. It had a little computer that monitered rpm and shifted the hub. It could be set for different shift points or be shifted manually. It worked pretty good but I won't have a car with an automatic and would not want a bike with one either.

They had one on tv called auto bike with weights on the spokes that moved out the faster you rode changing the gear somehow, it was way to expensive, a complete oice of crap, and didnt last long. Changing gears is so damn easy, and they made these actors get on bikes and crash and complain about them. Then they had some sorry ass excuse for a pro mtb rider test one in some race and he said it was awesome.