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Thread: chain-driven generator

  1. #1

    Default chain-driven generator

    Just saw this chain-driven generator on Deal Extreme:

    http://dx.com/p/me-0378-1000mah-bicy...e-black-229105

    That got me to wondering why we haven't seen more chain-driven generators. Obviously, they wouldn't generate electricity when the rider is coasting, but that might not be a problem with a battery or capacitor to smooth things out. They wouldn't have the slippage problems of tire-driven generators. Are there drawbacks? Inefficiency? Drag?

  2. #2
    Flashaholic* znomit's Avatar
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    Default Re: chain-driven generator

    I'm wondering how well it does when you change gears.

  3. #3
    Flashaholic* RetroTechie's Avatar
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    Default Re: chain-driven generator

    Quote Originally Posted by garyyoung View Post
    Are there drawbacks? Inefficiency? Drag?
    Most likely both. Between that and a dynamo built into the hub of a wheel: hub dynamo For The Win.

    Looks more like an (expensive) gimmick like you have so many on DX. That said: interesting concept.

  4. #4
    Flashaholic* Steve K's Avatar
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    Default Re: chain-driven generator

    Interesting that DX does show it mounted on a multi-speed bike. Too bad they don't have a video of it operating when changing gears. I can imagine ways to allow the dynamo's sprocket to follow the chain left and right, and considering that the dynamo is relatively expensive for a DX product, maybe they've incorporated such a feature?

    I'm a bit concerned by the white plastic sprocket that engages the chain. The dynamo load will be placed on one or two teeth at a time, and it seems like the sprocket teeth would wear fairly quickly.

    In general, the concept of driving a dynamo from the chain should be more efficient that a bottle dynamo driven off of a tire, but probably less efficient, perhaps, than a hub dynamo. Should be okay on a single speed or bike with an internal-gear-hub. I think I'd add something to be sure that the dynamo can't slip and fall into the spokes, though.

  5. #5

    Default Re: chain-driven generator

    Judging from the 4th picture, I'd guess that it accommodates changes in the height of the chain by sliding up and down two struts. But the only way I can figure it could move laterally (from small to big sprocket) is if the clamp swings around the chainstay. If so, it would twist the chain in most positions.

  6. #6
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    Default Re: chain-driven generator

    totally useless as it will not give power when not pedaling
    (has already been mentioned)
    why waste that "power"?

  7. #7
    Flashaholic* znomit's Avatar
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    Default Re: chain-driven generator

    Quote Originally Posted by yellow View Post
    totally useless as it will not give power when not pedaling
    (has already been mentioned)
    why waste that "power"?
    Did you read the specifications?
    Here's the important bit:
    Battery 1000mAh / 7.4V Lithium polymer battery

  8. #8
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    Default Re: chain-driven generator

    I imagine it would interfere less with gear changes if mounted midway between the chainring and rear cluster. I can see a dual use for this-namely to keep the chain from bouncing around. I've already had the chain bounce enough over some nasty potholes for it to come right off the chainring. All that said, I think these are a better idea than tire-driven dynamos but I feel a hub dynamo still wins hands down in terms of reliability and sheer elegance.

  9. #9

    Post Re: chain-driven generator

    It could work with derailleur system only if it was attached directly to front or back derailleur. Everything else would require overly complex and delicate centering system. This generator is meant to be used with single speeds and bikes with internal hub gears.

    If you want a reliable power source with little drag, hub dynamo is the way to go. As far as I can see, this machine has only one advantage; it is easier to assemble (and take away). If you buy a hub dynamo, you also need to buy the wheel (or build it yourself, which requires some special skills and/or time&patience). Other than that, I can see no advantages. It gets dirty, it has a plastic sprocket which wears out, it is exposed (thin plastic attachments, could be easily kicked between the spokes) etc.

    Of course, it also has a little battery. I wish there were more ways and better ways to utilize the power generated by hub dynamos. A charger for low power devices like phones, GPS, MP3, radio, tablets, flashlights, rechargeable batteries etc. would be nice. There are some solutions but mostly they are only used for powering bike lights in real time.
    In God we trust, all others bring data.

  10. #10
    Flashaholic* Steve K's Avatar
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    Default Re: chain-driven generator

    If one doesn't have the luxury of using a hub dynamo, I think the spoke dynamo would be preferrable to this chain generator. Relatively simple mechanically and can be installed on most wheels (possibly not with disc brakes, though). More efficient than a bottle dynamo, but slightly less efficient than a hub dynamo due to the typical need to use a gear train to increase the rotational speed to drive the little dynamo element.

    I used a FER2002 spoke dynamo for a year or two. Kinda nifty, but it was still cheap and wore out quickly. The kiss of death, IMHO, was that it wasn't suitable for high speed use, and I had a steep hill on my commute.

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