On 25 Nov 2003 23:43:18 -0800, (Chalo)
wrote:
It looks like the fella behind this CVT hydraulic bike is trying to

It says that it's a constant 1:2 ratio in the description. Where
did you see CVT?

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3641257316

Some people insist we want CVT, but hydraulically driven vehicles have
always had it available and are still rather uncommon. For instance,
snip
How did CVT become associated with the HPV community, when human power
seems to tolerate a wide range of RPM?

Probably a similar answer as to my question: Why do we have 10 speed
cassettes with sprockets that are one or two teeth different from
the next? Apparently, tolerance != efficiency (probably not enough
so to make the drivetrain efficiency loss worth it, though).

This is another feature that some have tried to provide, while others
wonder why. The benefits of four-wheel-drive in cars look similarly
esoteric to me, yet many people opt to pay a premium for 4WD or AWD

In cars, there are these effects:
1. In slippery conditions, you're less likely to get stuck
2. In slippery conditions, with only one axle driving, with a
steady amount of throttle (enough only to maintain a speed), hitting
a low-traction spot can result in loss of lateral traction for the
tires on that axle. This is not a big deal for FWD but easily causes
spinouts with RWD.
3. An AWD sportscar can produce a great powerslide (I think). I
imagine that it combines a classic RWD powerslide with the FWD
powerslide that I practiced (which, I believe, most people don't
know is possible, but is really easy). If the front lacks lateral
traction, and you're steering the way you want to go, and you give
it gas, the tires rotation will pull you in the direction they're
pointed. If the rear is loose, then the rear wheels give the
classic RWD powerslide.

AFAIK, a RWD powerslide is damn near impossible to do on clean, dry
pavement. FWD powerslides work fine with such traction.

Disclaimer: Don't try it! The "FWD powerslide", as I call it, is
extremely dangerous and requires a commitment to keeping full
throttle through the whole curve. As soon as you let go of the
throttle, the front wheels will let go and you will plow straight
ahead regardless of where you steer. Additionally, front traction
may exceed rear traction, in which case you have nearly impossible
to correct oversteer. If you brake, you will absolutely unweight
the rear tires and spin out.

cars. If such a thing were available for bikes (and without glaring
shortcomings), I wonder whether there would be any noteworthy handling
benefits. I don't ride my bikes in the muck, but perhaps those who do
would appreciate 2WD?

Handling benefits would only show up in very low traction situations
(snow, mud, deep sand). Actually, it would be useful in deep sand.

However, the point would be for steep, loose hills. You get to
concentrate on pedalling instead of having to devote attention to
maintaining traction. There is a hill I can't get up; I even have
super low gears on my MTB, but in the end, I can't seem to throw my
weight around for proper traction. The only person who I've seen
make it up the hill went in with loads of speed and was strong
enough to _never_ slow down at all. He was in a pretty high gear,
too.

Technique can make it work, but it sure would be nice to have
technology to help.

3) Integral braking, which the inventor's website mentions, but which
does not appear to be incorporated into this bike

I think that having a bike's drive and braking functions integrated
into the same apparatus is the most desirable potential feature of a
hydraulic drivetrain. Check valves could be adjusted to match
available maximum braking torque to the load, and the force required
to close the braking valves would be miniscule compared to that
required to actuate normal rim or hub brakes.

To be useful, it would need two-wheel-drive, and separate drives for
front and rear, else you wouldn't be able to proportion it. Sounds
cool.

5) No intrinsic configuration constraints
drive wheel far removed from the crank. Even a crank is not a given;
it could just as well be treadles or something else yet.

That would be cool, some different form of interface. What are
treadles? Maybe foot and hand pedalling could be combined.

chain drive. If you don't assume either of those things, then what?

How about a bike shaped like a cow? That would be cool.

I suppose the answer to that will have to await another feasible
alternative, if there is one.

There probably is one, and probably nobody will come up with it till
long after we're all dead. I hope that statement is wrong.

Chalo Colina
--
Rick Onanian