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Bicycle with flywheel

  1. Dec 30, 2007 #1
    Hi all, whilst bored recently I thought wouldnt it be a great idea to have bicycles where the pedals accelerate a massive flywheel and then you release some kind of clutch mechanism to propel the bike forwards.
    As i thought about it the main problem was what to use for such a flywheel (I was hoping to reach 20mph on flat), and either it therefore needs a balance between weight and speed...also since it would act like a gyroscope i wasnt sure where it would be positioned -- if this is unavoidable i guess i could just put up with the inability to steer (above your head with flat side parallel to the ground??)...
    Anyone have thoughts of a feasible way of building this??? I have to say it seems unlikely, mainly the difficulty of getting the flywheel to store enough energy... but if i could pull it off it might be good fun??? Thought some mechanical engineers might be good people to help,
  2. jcsd
  3. Dec 30, 2007 #2


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    Sounds like something I would think of.
    Overcoming the gyroscopic effect would be mechanically difficult while still being able to transfer energy. An electromagnetic motor/generator flywheel with a triple gimbal mount might work.

    described here under inertial navigation:
    Hmmmmm.... There's something to think about; adding a second flywheel to counteract precession.

    Also, rolling resistance is proportional to weight. Your flywheel would have to be light enough to not exceed the energy recouped. If you live in the city, it might be feasible. But on long hauls I don't see it as anything but a burden to carry around.

    Of course there are obvious advantages:
    1. Regenerative braking.
    2. You can power up the flywheel at stoplights. No reason to just sit there.

    They discussed your idea a bit at halfbakery.com:
    I've been researching energy storage options for about 2 years, and here at the forum for about 3 weeks now. I was leaning towards a hydraulically compressed coil spring system, but your electro gimbal mounted flywheel sounds like a good option to consider. I'll be back if I ever get the math done.

    ps. I'm not a mechanical engineer, but thought I should throw in my 2 cents worth of research.
  4. Jan 31, 2008 #3
    I just ran across your post and I might be working on the same thing your talking about.
    Check out some of my videos on Google and click on ( from user) to see all of progress so far.
    http://video.google.com/videoplay?docid=-5591140509449393106 [Broken]
    copy and paste this I am kind of new to this thing here

    The viedo is of my brother riding there are no brakes yet. I am working on the handle bars so I can pump them up and down with a pull rope off a lawn mower I think it might give me more power to the pedals.
    I have 72 speeds to gear up the flywheel 18 from the bike sprockets and 4 gears from a lawn mower trans. top geat is 1:128 time on the flywheel.
    I put a bike speedometer on the flywheel to see the RPM's I have to multiply it by 9.5 to get the right RPM the way it is set I need to change it to reed the right numbers.
    The flywheel is a pc. of 1/2" steel plate I cut at work on a laser it is about 145lbs and 36" in diameter.
    Last edited by a moderator: May 3, 2017
  5. Jan 31, 2008 #4


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    Just spotted this thread, i have been thinking along this line. I have an electric bike (450 watt), the thought that intrigues me is to have two counter-rotating tesla turbines, mounted vertically, and drive two exaust impellers with your legs(geared for a high RPM). The reduced air pressure at the center of rotation, lets you take advantage of increased wind resistance as you go faster. Getting the speed of the turbine blades to a high RPM will let you draw short cycles of electric current to help keep the batteries charged.
    If i understand Tesla the turbine is a thermaldynamic converter, warmer air in, colder air out, based on energy converted.
  6. Dec 26, 2008 #5
    I independently came up with the same idea while trying to think of what to write for an essay for the Cornell engineering application. I think that the best way to do this is to mount a flywheel inside the rear wheel and have it rotate on a bearing on the rear axle. To begin to spin up the flywheel during regenerative breaking, a clutch would be activated and connect the flywheel and wheel in a low gear ratio (it has to be specially geared to get enough speed and therefor angular momentum). The clutch would just be a rotating rubber piece connected with a chain to the flywheel that would connect by rubbing against the metal portion of the bicycle wheel. So, basically, the rider pulls the clutch, which connects the rubber piece to the wheel which spins at a high speed, which directly connects to the flywheel, which then rotates at a high speed
  7. Dec 26, 2008 #6
    by the way check out "gyrobike on youtube," It proves that the idea of a flywheel actually helps with balance.
  8. Jan 7, 2009 #7
    Gyro Bike Test two is real funny, the bike get away from him and crashes in to his car.
    Last edited by a moderator: Sep 25, 2014
  9. Feb 18, 2009 #8
    I have a pretty well worked out design, and have seen a considerable amount of information on this subject over the 15 years in which I have been interested in such a device. I would love to partner with anyone interested in prototyping, especially, but not restricted to, the New York area. Call me - it can't hoit! 212-440-9901
  10. Nov 13, 2009 #9
    a flywheel is ideal for this - a better form of energy storage in many ways than a battery (lightweight, high power density, able to release energy fast, etc.) the gyroscopic effect would actually be beneficial to stability, as long as it were aligned parallel to the wheels (which also act as gyros, when in motion.) another good option would be compressed air (using a carbon-fiber tank), or perhaps a combination of the two. these could capture energy through regenerative breaking, and could also be recharged by plugging in. it seems very feasible. i'm surprised noone has come up with such a system comercially yet. they would be especially popular in europe where bikes are already a very common form of transportation.

    there are battery-powered devices to provide extra boost on acceleration (e.g. schwinn's "tailwind"), but batteries are very bulky and heavy - less than ideal for a bike. as far as i know, no mechanically stored energy system on the market to date...
  11. Nov 13, 2009 #10


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    Old thread. A bunch of binary posters. Two oldy moldy tinkerers putting in their 2 cents worth.

    Based on the following video, how fast would this guys 50 lb flywheel have to rotate in order to store 1500 joules of energy?

    https://www.youtube.com/watch?v=<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/JVvfq7NyNKU&hl=en_US&fs=1&"></param><param [Broken] name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/JVvfq7NyNKU&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

    And why did I pick 1500 joules?

    Love that video. Been there, done that. :)
    Last edited by a moderator: May 4, 2017
  12. Apr 23, 2010 #11
    How about this for a idea - not sure if it would work but a new build on the back wheel would need done. Build the flywheel into the center rear wheel - add some gear ratio unlike a toy car then when the flywheel reaches speed. Centrifugal force kicks in and the flywheel moves further out in quarters(splits) from the central hub and when at a max centrifugal force the fly momentum would then catch the wheel and add thrust to the ride. When braking it would have to be stoped or the slowing of the wheel would cause the flywheel to retract but keep some momentum. This would work probably on longer hauls and not stop start bike rides.
    Centrifugal force could be controlled by springs. Pulling the flywheel (made of numerous counter weights) back once the bike slows down.
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