Bicycle Design

Compressor pneumatic bike

I always like it when industrial design students and recent grads send me renderings and descriptions of their bicycle related school projects. Not only is it interesting to see their concepts, but also those submissions make for pretty easy posts on my part (a good thing for busy Fridays like today). A couple weeks ago, James Breaux, a recent ID graduate of the University of Louisiana at Lafayette, sent me his concept for a bicycle powered by a pneumatic system. In an effort to keep this post easy, I’ll let James explain the idea in his own words:

“The Concept: A pneumatic system that replaces the chain. With every crank of the pedals, compressed air is pushed through the chain stays, which then turns the rear wheel, similar to the cannonade jack knife concept. However, one main difference in my concept (other than the pneumatic/hydraulic difference) is that when the rider is coasting downhill the bike will store up air inside the main chamber of the frame through a flywheel system. This also acts as an air brake and the stored compressed air can be released while pedaling uphill as an added boost (not meant for long propulsions or to replace actually pedaling). The frame of the bike can be manufactured through a process called super forming, which is essentially vacuum forming metal that is heated to very high temperatures, the tubing of the bike can be made lighter and completely air tight.

Here are some stats that an engineering professor helped me come up with for the bike

– A 180lb person riding a 30lb bike can travel 50 meters at a 5% incline with the bike filled at 20psi working at a 25% efficiency rate

– It takes about an hour to fill 1.5 cubic feet of air at 50psi with a low voltage compress that is rated at 1000th of a horsepower

-A human can put out between a 10th to 1 horsepower. This means the frame could refill the air compression in 10-15 minutes through coasting or pedaling.”


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16 responses to “Compressor pneumatic bike”

  1. Harv Avatar
    Harv

    “- A 180lb person riding a 30lb bike can travel 50 meters at a 5% incline with the bike filled at 20psi working at a 25% efficiency rate”

    25% efficiency? Pretty poor when compared to a chain-drive system which runs at a nominal 99%. Thermal considerations are quite significant here. When a working gas is compressed, heat is released. This heat is transfered away and its energy is lost. Only way to mitigate this is with a lot of insulation. Not easy to do considering the physical size constraints of a bicycle frame.

    Next idea? 🙂
    .

    Reply
  2. eradler Avatar
    eradler

    The idea might be rechecked for using the braking energy but you have to come forward with pneumatic motor efficiencies > 80% to compete with electric powertrains using supercaps

    Reply
  3. Ron Avatar
    Ron

    James,

    Interesting idea. Low efficiency as harv said. This is also an age old concept, several patents exist :

    1. Deneal’s Locomotive Drive

    2. Z.T Ubil’s Frame Air Reservoir

    3. Moore’s upright reservoir on seat tube

    Not a marketable technology in my view.

    Reply
  4. bikesgonewild Avatar
    bikesgonewild

    …ron…what’s interesting on the #3 moore’s bike from 1898 is the suspension stem…

    …the engineer’s posting in, lead me to believe that at this juncture, the compressor pneumatic bike concept is a case of hans & franz wanting to pump us up & really nothing more…

    Reply
  5. Anonymous Avatar
    Anonymous

    Hey, c’mon …

    You’d always have air at the ready for filling tires.

    Reply
  6. Fritz Avatar
    Fritz

    Horribly inefficient as others have noted, but you have to give the kid points for thinking waaay outside of the box. I like this kind of creativity — who knows what kind of interesting and nonintuitive solutions these folks might eventually come up with?

    Reply
  7. jimmythefly Avatar
    jimmythefly

    I’d love to have some sort of regenerative braking, I can’t stand hitting ared light and feeling like I’m just wasting all that energy into heat on my brake pads. All the solutions seem to end up too heavy, where the energy gained wouldn’t offset the extra weight. (electric, flywheels, this).

    Reply
  8. Hallian Avatar
    Hallian

    I certainly like the thinking, I heard somewhere that the urban cyclist uses somewhere in the region of 70-80% of their energy accelerating again after having to top at lights or slow down for pedestrians/ traffic etc. A regenerative solution would certainly be useful but using a compressible medium in the drive I am certain is not practical. The bike would feel horrible to ride if nothing else. How about hydraulic drive with some kind of accumulator re-gen?

    Reply
  9. Richard Avatar
    Richard

    I actually graduated with James, and I know that the 25% efficiency was simply a base figure, and not at all meant to be the actual working efficiency.
    Actual figures would be much higher; the 25% was a “worst possible scenario” figure. He’s got more research that backs his design up, maybe he could provide the higher end of the spectrum for skeptics.

    Reply
  10. Andy Cochrane Avatar
    Andy Cochrane

    i like the idea of regenerative braking in bikes, and this design is really interesting in approach- the efficiency issue would need to be worked out for sure. i wonder what a hydraulic drive train would be like (it would be heavier than a chain) in conjunction with some sort of air compression for energy storage… might that solve some of the efficiency issues?

    Reply
  11. Anonymous Avatar
    Anonymous

    I have been working on a concept like this myself. Not using compressed air though. I think for about 3 lbs I can build a regenerative brake system with 94% effeciency.

    Reply
  12. Justin Avatar
    Justin

    It would add an interesting element to racing…the ability to store energy. If you could do a bunch of work before a hill climb to store energy then open a throttle to zip up the hill that’d be pretty awesome. The strategy would totally change.

    Reply
  13. Anonymous Avatar
    Anonymous

    Leave the drive train alone. That would be spinning your wheels. For pure regenerative braking, efficiency doesn't matter. The energy your storing was 100% inefficient to start with. What is important is the component weight. If the added components could be transparent to normal riding until engaged (during braking), it would be a win for sure. Time to get clever with materials and triggering mechanisms. As to thermals, stopping at a light and then reclaiming the energy seconds later gives the gas little time to transfer heat outside the system. The tricky part would be the non linear response of the system.

    Reply
  14. linear actuator Avatar
    linear actuator

    Pneumatic tools usually requires compressed air. Now that's pretty impressive

    Reply
  15. ACB Avatar
    ACB

    Old post, but worth a shot, well as fellow ID here, I’d say it’s a growing process of Innovation, but to say that compressed air generates continuous motion for the bike (most unlikely), many factors needs to be re-considered (super vacuum formed metal?I’d say it’s metal forging…expensive) that’d be like filling a tank of compressed air size of a hummer (takes a while,just to go round a block) you’d be pedaling to nowhere,good job though of generating “out of the box” innovation,you’d never know where you could pick up where somebody else left behind

    Reply
  16. Tom Waxman Avatar
    Tom Waxman

    its a concept previously administered to
    steam engines and steam power transmition,
    Consider this :
    As the rider Pedels forward , two pneumatic
    piston pumps which are pinion attached to the designed rotary pedal crank arms ( one for each side , pumps / pistons are horizontally opposed )
    these piston pumps continuesly work in unison stroke by stroke , filling the bike frame
    with compressed air. The pumps are also designed to be pistons. As the bike frame tank reaches capacity a reserve capacity tank no 2 located in the drink bottle holder fills with air and becomes the primary tank, a computer controller decides when to open and shut
    four solenoid valves.
    At 30km an hour for 5-10 mins the riders tanks have built up 300psi.
    Now for the cool part , The controller detects minimum pressure acheived based on
    air input and bike speed , and the reverse flow system from the filled tanks is opened.
    a crank angle sensor tells the controller to open the reverse flow too the pump/pistons.
    The rider is still compressing air with the other pump/piston.
    The rider now has 300 psi of air , pushing the rotary pedal crank arm forward releiving the amount of actual power/ torque required from the riders legs.

    not perpetual , the rider has to pedal too move forward but
    but instead of the riders legs doing all the work the piston/pumps
    releive some 30-40% of energy required to keep the bicycle moving.!

    thought this up in my brain a while ago and have been workin on designs.
    use this free infomation to change the way we ride!.

    Reply

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