Bicycle Introduction and Background

Karakuri: How to Make Mechanical Paper Models That Move, by Keisuke Saka is a book that teaches you how to make paper models of mechanisms to create desired moments. For my project I recreated an example of a bike in the book. The person riding the bike pedals as the front wheel rotates.

The model used 3 gears, two large and one small. The small gear is attached to the input and the other two are connected in series. The top most gear has an axle going through that is bent on both sides of the gear to represent on a bike. This pedal is the input to the four bar mechanism made by the bike (ground), pedal, lower leg, and upper leg. This motion causes the knee to be 21.4 mm above the axle at its highest and 6.8 mm above the axle at its lowest.