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-   -   StringBike. No chain, just strings. (http://www.bikeforums.net/folding-bikes/682242-stringbike-no-chain-just-strings.html)

puppypilgrim 09-22-10 11:21 AM

StringBike. No chain, just strings.
 
http://i52.tinypic.com/jpv8dz.jpg

From Rohloff to Pinion to Strings. :-)

Appears to have 19 speeds and can be shifted while stationary. Total range of 250%. Wide Q-factor. No dishing needed for the wheels. Due to symmetry of drivetrain, perfect alignment of drive components. The drive does not require lubrication or maintenance and uses a polyethylene rope.

Left and right sides do not need to use the same gearing. Therefore if one has a disability, a bike could be tailored to meet asymmetric strength requirements.



How It Works
http://www.stringbike.com/principle-of-operation

How To Change Gears
http://www.stringbike.com/Change%20of%20gears

How Efficient Is It?
http://www.stringbike.com/Efficiency%20of%20the%20drive

How Does It Feel Compared to a Chain Drive?
http://www.stringbike.com/Driving%20curves
http://www.stringbike.com/Smooth%20driving

Urbanis 09-22-10 12:54 PM

Intriguing! I'll be interested to hear the engineer types on this board weigh in.

mustachiod 09-22-10 01:02 PM

:popcorn

in before the engineer debate

Fast Cloud 09-22-10 02:44 PM

Those cams make it look sort of like a compound bow. I'll pass.

jur 09-22-10 03:06 PM

Very interesting.

:( As always, I am curious about the efficiency numbers (not wordy descriptions). As usual, there are no numbers.
:) It looks like it has the capability to be made really light. The current design seems heavier than a derailer system. The rear hub needs work for this.
:) Looks like it could be almost completely dirt-proof.
:( It looks like it needs a special frame.
:( It uses lots and lots of extra bearings.
:) It uses far fewer bearings than in a chain.

The inventors need to show not innovation but a clear improvement on what is already available, from efficiency, cost and weight POVs.

puppypilgrim 09-22-10 03:28 PM

I don't know if its a better mousetrap.

Website says no lubrication or maintenance is needed. Seems to have complex moving parts to me. And complex to me is not so good but what do I know? The pedaling feel is not like a chainring. More of a lever action. Nothing wrong with the innovation I suppose. The only thing that would need replacing over time is the string\rope ad bearings. The hub would last the life of the bike.

sjdude 09-23-10 08:44 AM

:thumb:
Thank you. Good share!

I've got a few questions though.
Are'nt there springs in the rear hub to return the strings and crank to the pre-power delivering phase?
And won't this "return" tendency zap rider energy by acting in the opposite direction of rider applied moment?

rhm 09-23-10 08:48 AM

1. Seems to me I saw something very like this in a transportation museum in Germany... on a bike from the turn of the last century.


2. And it folds... how?

Urbanis 09-23-10 09:30 AM

Quote:

Originally Posted by rhm (Post 11511550)
1. Seems to me I saw something very like this in a transportation museum in Germany... on a bike from the turn of the last century.

Which just goes to show once again that all major innovations in bicycle design--including ones we think of as very modern--were originally developed in the 19th century: folding bicycles, internal gear hubs, shaft drives, etc.

Smallwheels 09-23-10 07:31 PM

In all of the videos with someone turning the cranks by hand the motion looked very jerky. I think belt drive with an internal gear hub gives the same advantages without so many parts.

puppypilgrim 09-23-10 08:06 PM

True Smallwheels. Simpler and cheaper. For me though, I think a singlespeed chain drive is still tops for ease of use and maintenance.


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