This design is for bikes that have no extra space under the seat tube for mounting a traditional friction drive system. Constant friction between motor and tire is maintained by two 1.2mm springs, and adjusted with zip ties on the other end of each spring.

BUILD INSTRUCTIONS
https://gum.co/LqmWJ

PART LIST

• Motor
  https://www.banggood.com/custlink/DDvKqn1Pv7

• VESC
  https://www.banggood.com/custlink/GD3KMLY6lf

• Throttle Grip
  https://www.banggood.com/custlink/m3v3UjR0gv

• Arduino for Analog to PWM converting
  https://www.banggood.com/custlink/Kvvmkoh00h

• Tension Springs

• Screw
  1pcs M8 x 60mm bolt
  2pcs M3 x 30mm bolts
  4pcs M4 x 35mm bolts
  4pcs M4 nyloc nuts

Video
https://youtu.be/CECEI_Vuol0