Bicycle Mechanics - What was the inventor thinking

when he designed this monstrosity?

http://cgi.ebay.com/Cannondale-Prototype-Fluid-Drive-Hydraulic-Bike-Bicycle-/270655833311?pt=LH_DefaultDomain_0&hash=item3f045844df

That's actually cool as hell.
The seller's price point is a little off, but kudos to the inventor for coming up with an entirely new drive system.

That's actually cool as hell.
The seller's price point is a little off, but kudos to the inventor for coming up with an entirely new drive system.

Anything hydraulic is extremely inefficient, think of the inefficiency of an automatic transmission.

Maybe it's a constantly variable gearing setup? I guess that would be an innovation.

VEry cool.

Just because we've always done someting a certain way does not me that is the best way to do it.

It's a great proof of concept, but I agree $10 is a bit too much.

If the bike has no torque converter,I would be pretty much direct drive.You would have to compress the fluid in order to lose power,that isn't going to happen.

Looks like there could be vanes in the system though,meaning torque lose or gain,depending.

Efficiency of fluid drive is real close to chain drive.About 95% for fluid/98% for chain.

If the bike has no torque converter,I would be pretty much direct drive.You would have to compress the fluid in order to lose power,that isn't going to happen.

Looks like there could be vanes in the rear though.

Efficiency of fluid drive is real close to chain drive.About 95% for fluid/98% for chain.

There would be loss of power through fluid friction as it passes through the system, and it is possible that there would be further losses if there were vanes or gears where some fluid 'passes,' but still a good attempt!

I have always wanted to have my pedals driving a generator and the generator powering an electric motor at the rear wheel, but I know it would not be particularly efficient so I have not spent the time trying it.

There have been numerous successful experiments with fluid drive systems on the front wheels of motorcycles to come up with two wheel drive on them. Problem has always been added weight and added power requirement.
IMHO, you will be better off trying to build a modern shaft drive system for a bicycle, specially with the lighter materials now available....Uhmmm......maybe hollow CF shaft and drive housings and light alloy geartrain parts......you might even be able to get rid of most lubrication requirements with the right materials.

Chombi

Interesting rake on that front fork.

There have been numerous successful experiments with fluid drive systems on the front wheels of motorcycles to come up with two wheel drive on them.
You will notice none of them are in production in any useful numbers

Hard to not lose when efficiency gets compared with a well oiled clean roller chain.

A good mechanism for a pedal powered drive system, that application to a bicycle a bit kludgy, especially one with the fork backwards.

but there are lots of other machines that could benefit from a human power source

a flour mill, a water pump, maybe a pedal powered Forklift?
but thats 3rd world uses , or maybe this one when the oil goes away.

If the bike has no torque converter,I would be pretty much direct drive.You would have to compress the fluid in order to lose power,that isn't going to happen.

Looks like there could be vanes in the system though,meaning torque lose or gain,depending.

Efficiency of fluid drive is real close to chain drive.About 95% for fluid/98% for chain.You may want to revisit your numbers. Fluid-drive is efficient on large powerful systems, but on something as small as a bike with the small power-output, you're presented with a lot of drag from the seals.

yea, makes a big difference Too, if the motor is a few hundred watts at best,
rather than a few hundred horsepower.

Not my numbers.That's industry standard for chain vs fluid drive in general.

Efficiency has nothing to do with size or input.

On chain drive,if 10 HP goes in,9.8 HP come out.100 HP goes in,98 comes out.The only difference is the size of the chain. Same with fluids.

needs a motor. why pedal a bike that weighs 55lbs

My point exactly, human powered stationary tools, in a dusty environment,
like a Grist Mill.

or an inboard pedaled outboard prop boat motor..
flexible outboard so banging into bottom won't break so much stuff

with a bunch of driving pumps and just a couple driven pumps all the partier's
on the houseboat could change the location of the house party.

VEry cool.

Just because we've always done someting a certain way does not me that is the best way to do it.
In the case of bikes what we have now is the best way to do it. 160 years Evolution has brought us today's bike.

Not my numbers.That's industry standard for chain vs fluid drive in general.

Efficiency has nothing to do with size or input.

On chain drive,if 10 HP goes in,9.8 HP come out.100 HP goes in,98 comes out.The only difference is the size of the chain. Same with fluids.Don't know which industry you're quoting, but everything I find about hydraulics says 85% best-case-scenario:

http://www.machinerylubrication.com/Read/659/hydraulic-pump-condition

You also have to differentiate between volumetric-efficiency versus mechanical-efficiency. Just because you can get the output-shaft to run at 97.5% of the speed of the input, doesn't mean that 97.5% of the power got there. It's actually much lower than that due to various factors such as viscosity and shear friction.

You will notice none of them are in production in any useful numbers

Yes, because the technology is still in it's infancy, but the major motorcycle company, Yamaha, had been working on prototypes for a couple of years now and the results have supposedly been good so far I think there is also a small company out there that's already selling a conversion kit for a certain dirtbike already. Two wheel drive isn't new in motorcycles. Rokon had been making two wheel drive bikes since the early 70's with a mechanical drive to the front wheel. The bike they made was more of an expeditionary/utility bike and is more for slogging slowly through the wilderness. If Yamaha does push through with 2 wheel drive bikes, I think the armed services and other government departments (Police, DNR, Homeland Security...etc) will be very interested. the niche is certainly there.

Chombi

when he designed this monstrosity?

http://cgi.ebay.com/Cannondale-Prototype-Fluid-Drive-Hydraulic-Bike-Bicycle-/270655833311?pt=LH_DefaultDomain_0&hash=item3f045844df

Man! That's got to be ONE slow bike!

Don in Austin

In the case of bikes what we have now is the best way to do it. 160 years Evolution has brought us today's bike.

Perhaps. Perhaps not.

The only true wisdom is knowing you know nothing.

Man! That's got to be ONE slow bike!

Don in Austin

+1 but think of the cardio workout.:p:thumb:

But..but...but...but....IT'S A CAD!!!!!!

Actually, it's been done before. An inventor built a streamlined recumbent bicycle (Human Powered Vehicle).

The problem was, it leaked hydraulic fluid all over the Velodrome Track (Polished Wood) , and they made him go out with a mop and clean up the mess he made.

I have always wanted to have my pedals driving a generator and the generator powering an electric motor at the rear wheel, but I know it would not be particularly efficient so I have not spent the time trying it.

I have a front dyno hub driving a rear electric hub motor both using special magnets I got from an Inca Priest when I was mountain biking in the Andes. I give it a push, the dyno starts driving the wheels and I can accellerate up to 60mph with zero input power. ;)

Perhaps. Perhaps not.

The only true wisdom is knowing you know nothing.
The more I learn the less I know. Took 50 years to understand that.

Homilies don't press my buttons.

The fact is, there are very real constraints applying to the design of a bike drivetrain... it has to be lightweight, durable, and efficient.

I'd like to see someone try to say that doesn't mean it has to be quite simple...

So if it has to be so simple, how many decades do you need to be pretty sure you've found the best way?