StringBike no chain!!

 The Stringbike is a bicycle that uses a rope and pulley drive system instead of a traditional bicycle chain and sprockets. It uses two Dyneema ropes attached to pulleys attached to swinging lever and cam mechanisms, one on each side of the bike. These mechanisms replace the round sprockets found on chain-driven bikes.
https://en.wikipedia.org/wiki/Stringbike



 總部位於匈牙利首都布達佩斯的 Stringbike 重新設計整個傳動裝置，用高強度傘繩代替鏈條，把自行車改成上圖的樣子。 它是這樣運作的：. 當你雙腿蹬踩踏板時，踏板的傳動桿會帶動形狀不規則的轉盤前後擺動，擺動過程中，轉盤會扯動傘繩，而傘繩連著轉盤和後輪，於是最終帶動輪子向前捲動，讓自行車前進。
 http://technews.tw/2017/11/25/stringbike-string-to-move/
 

http://www.stringbike.com/stringbike_bike_dsigners.html