Introducing Stringbike: the bike with no chain

[legalskier]

(PhysOrg.com) -- Hungarian bicycle designers have unveiled their new Stringbike in Padova, Italy. The design replaces the traditional chain with a symmetrical rope and pulley system, which they say is more efficient, makes for a more comfortable ride, and provides improved maneuverability around winding streets. The new system is more complex than a chain and gears and consists of a rope and pulley on each side of the bike. The rotation of the pedals forces arms at each side to swing forward and backward on its shaft. When moving forward, the arm pulls the driving wire that is wound around a drum on the rear wheel, forcing the wheel to rotate. The arms at each side alternate so that when one is moving forward the other is moving backward. The new system has 19 "gear" positions and the transmission ratio can be changed at any time by turning a shifting knob on the right handle grip. This moves the pulley shafts up and down along a traction path on an eccentric disc, which has 19 notches to adjust the height of the pulleys and distance between the center of rotation and the shaft. The gears can be changed even if the bicycle is stationary, but gear change speed increases with the speed of the bicycle.

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[bvibert]

Interesting idea. Not too sure how well it would hold up in an off road environment though...

 

[marcski]

I don't see where the design is that much simpler? While there is no rear cassette, the pulley system seems to be just as complex or even more so? Plus wouldn't the "strings" be even more apt to stretching with use than a chain?

 

[mondeo]

Could always go to belt drive. That's quieter.

Seems like reinventing the wheel to me. Chains are plenty efficient (mid-90% range.) But I should probably clean mine at some point.