A while back I shared a test run of my air powered bicycle; this is an overview of the mechanics.

The pedals are connected via chain and pulleys to an air compressor, which fills the tank. The tank then powers an air motor which consists of two double-acting pistons driven by a 3D printed cam - these turn a shaft which turns a chain connected to the bike's original rear sprocket.


While it was a cool project and I learned a lot... the efficiency is something like 3%. A regular bike is 90% efficient or more - there's almost no loss in the chain parts! This machine loses a TON of energy to heat - as evidenced by the compressor melting its output hose! I replaced the output with a copper tube and added the cooling fans - you can see the blue glow when they're running.





I'm also working on part-ejecting 3D printers under the PrintShift project - check it out:
  / printshift