Ditch Your Chain
The Future is here…
Earlier this week, a Hungarian-designed chain-less bike was introduced in Padova, Italy. The bike has been developed by a team of designers at the Schwinn Csepel Zrt. Here is a video that shows how the bike works:
The bicycle has a new driving system using steel wires instead of chains, which has the following main units:
PEDAL This is basically identical with those of conventional bikes. Respective pedals are arranged at either side of the frame, and the cyclist rotates the two pedals around a central pivoted axis.
ECCENTRIC DISKS The pedal axis rotates these discs at both sides of the frame. The discs has a specific, kidney like shape which determines the driving characteristic i.e. the angular displacement of the rear wheel of the bicycle as a function of the angular position of the pedal shaft. The chosen shape provides for a conventional driving characteristic i.e. the same as if a chain-driven bike with circular gears were used. In a more expensive model the discs can be changed with other ones having different shapes, whereby the driving characteristic can be changed in a tour or in a contest, to load different muscle groups.
THE SWINGING UNIT Comprising a pair of oppositely swinging arms arranged for swinging movement around a pivoted auxiliary axis. The rotation of the eccentric discs results in the swinging movement of the arms in forward and backward direction.
TRANSMISSION (SPEED) CHANGER This unit is a controlled slide. It changes the longitudinal position (height) of respective pulleys guided along the swinging arms. The height of the two pulleys is always the same. When the pulley is in the outermost position, the transmission ratio is at maximum, while in the innermost position this ratio is at minimum.
REAR SHAFT UNIT Comprises respective freewheels at each side. The outer surface of the free wheels defines respective cable drums.
WIRES Interconnecting the respective cable drums with the pulleys. One end of each wire is attached to the cable drum and the other one to the frame.
CABLE BIASING A double cable reel arranged at the upper portion of the rear fork, just oppositely relative to the rear brake. The two reels are spring biased to each other, and they hold thin biasing wires wound around the respective cable drums. The role of this means is to keep the pulling wires always under tension.
[Via Jack Curry]