In article ,
Simon Brooke wrote:
(Chalo) writes:

1) True continuously variable transmission ratio, which this bike has

Some people insist we want CVT, but hydraulically driven vehicles have
always had it available and are still rather uncommon. For instance,
Hondamatic motorcycles never caught on, though their system seemed to
work as intended.

The Hondamatics didn't catch on because motorcyclists in the US
are interested in sport, and not solely in practical commuting.

The Rokon and Husqvarna automatic dirt bikes were moderately
sucessful but failed because of reliability issues.
(Rokons would lose drive if the belt got wet, and the Husky
transmissions would blow up and give you four automatic neutrals).

OTOH, there are a lot of new Audis running around with "six speed"
computer-controlled CVTs.

which operated through pairs of opposed cones with a belt linking
them; the belt was automatically moved from one end of the cones to
the other to vary the ratio. The system was remarkably effective and
seemed quite a good thing, but as you say hasn't been widely adopted
(I think there were limitations on how much power it could
transmit). Similarly, hydraulic CVT gearboxes were around on farm
tractors when I was a boy, but the vast majority of tractors continue
to have mechanical gearboxes.

Most newer small diesel and garden tractors in the US are hydrostatic.
Essentially zero maintenance, and MUCH easier to use for mowing
or front-end loader work... or anything except plowing straight lines.


All wheel drive on an off-road vehicle is generally a good thing,
provided that you have limited-slip differentials or the
equivalent. If one wheel spinning brings the whole vehicle to a halt
there isn't a lot of point. However, a pushbike is much lighter than
other off road vehicles. If you do get into a situation where the back
wheel just can't grip the usual solution is to put the bike on your
shoulder and walk a bit. So AWD isn't that big an issue, although it
might be useful on loose, gravelly climbs.

The front wheel doens't have much traction on climbs since
all the weight is transfered to the rear.


Yamaha have done some experimental 2wd off-road motorcycles, and
have even run them in rally raids (similar to the Paris-Dakar).
The hydraulic 2wd WR450 is supposed to go on sale to the general public
in the 2004 model year, although I'll beleive it when I see it.

The description I read sounds like it's very different from
a normal rwd dirt bike to ride.


However, the inventor of this creation claims only 90% efficiency. Am
I not right in believing that deraileur systems achieve about 93%? I
know 3% isn't much, but then bicycles are not exactly high
powered. Still, an interesting system - would definitely be fun to
play with!

I think bicycles are more like 98% efficient, if that's the
case 90% would really suck.


Eric