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  1. #1
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    Brompton Wiki - Adding electric assistance

    Because of the many threads that come up on the Brompton yahoo discussion forum about adding electric assistance and that many of the enthiasts like myself have had to type and re-type replies, I have agreed to update the associated area on the Brompton wiki.

    As I am not a reseller hopefully it will be independent, although I must confess that having converted several Bromptons to electric assistance I have my favorite components.

    However all my conversion have been DIY from motors sourced directly form China i.e. building wheels and adding electrics rather than purchasing the many kits that are now available.

    Its still a work in progress, but I have added a few links at the bottom of the page to kit and component providers.

    http://bromptontalk.wikispaces.com/Electric+Assist

    There is also a nice video showing exactly how a kit can be fitted. Although it is provided by a specific supplier the process is pretty similar for the various kits available.

    In addition much of the information is also transferable to other small wheeled bikes and folders. I myself have also added assistance to a Dahon Uno and a Xootr Swift.

    Regards

    Jerry
    Last edited by jerrysimon; 07-16-13 at 07:56 AM.
    Brompton M2L (SRAM A2), Brompton M2L(X), Dahon Uno (SRAM A2), Both Swift Xootr & Moulton TSR2 now gone

  2. #2
    Senior Member Still Pedaling's Avatar
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    I enjoyed that first video. It doesn't seem all that difficult really, but what about all that cable hanging down, did he not strap it securely to the cross tube?

  3. #3
    coprolite fietsbob's Avatar
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    Where does the power torque windup go?

    the security hooked washer and the dropout slot seems inadequate.

    saw the results of a motor stripping the dropouts of a Motor
    retrofitted on a Catrike, .. owner ruined the frame, when 1 end was not fully seated.

    he hot-dogged a corner and flipped the trike
    I suspect then didn't do adequate safety inspection .
    Last edited by fietsbob; 07-16-13 at 11:48 AM.

  4. #4
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    The first video is using a heavier more powerful motor and those replacement forks and dropouts are really beefed up. As you say a lot of wiring mess plus I don't like that battery on the seat post.

    The second video is where you fit a kit into your existing forks. The wiring and battery is much more subtle being in the bag. This motor is less powerful 180W but adequate and I have used a similar motor for the last 3 years and 6000 miles pretty much daily, without any problems with motor or frame

    As stated I am not a retailer of any of the systems listed and have no affiliation with them, but I do buy all the component parts direct from China to make up my own kits. I have converted a few family and friends bikes but pretty much at cost of the parts only.

    Regards

    Jerry
    Last edited by jerrysimon; 07-16-13 at 12:21 PM.
    Brompton M2L (SRAM A2), Brompton M2L(X), Dahon Uno (SRAM A2), Both Swift Xootr & Moulton TSR2 now gone

  5. #5
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    Jerry - Thanks for posting this. I have always been intrigued by electric bicycles but have never owned one. From reading your posts in the past, I know that you have explored the world of electric bikes, particularly folders, and I believe that what you have assembled DYI is an ideal arrangement, preferable to what I have seen available as kits or fully outfitted bikes, thanks to the high value you place on light weight.

    Maybe someday I will take the plunge, but until then, I will take vicarious enjoyment from your efforts, and those of others.

  6. #6
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    Quote Originally Posted by DoubleDiamonDog View Post
    From reading your posts in the past, I know that you have explored the world of electric bikes, particularly folders, and I believe that what you have assembled DYI is an ideal arrangement, preferable to what I have seen available as kits or fully outfitted bikes, thanks to the high value you place on light weight.
    Thanks. I have spent a lot of time and money designing and installing the lightest system possible, but then for me it is a hobby

    Given that a Brompton is often purchased for its small fold and portability, I considered minimising the weight of any electric assistance is important. Maintaining/not compromising the fold is also one of the other big challenges when retrofitting e assist.

    After three years of tinkering this is my final solution for lightweight portable e biking.




    An M2L-X with motor fitted that weighs 11.5kg (same as a stock M3L) in terms of carrying with battery and controller in the bag.

    Not cheap, but by far my most successful portable conversion.

    Regards

    Jerry
    Brompton M2L (SRAM A2), Brompton M2L(X), Dahon Uno (SRAM A2), Both Swift Xootr & Moulton TSR2 now gone

  7. #7
    coprolite fietsbob's Avatar
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    they all require spreading the forks to 10+?

  8. #8
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    The 80mm wide motors I use, require about 5-6mm spread though in practice wider as they spring back.

    The dropouts also need to be opened out from 8mm-10mm to accept the flat of the motor shaft i.e. about 1mm on each edge.

    All shown in the video on the wiki.

    Jerry
    Brompton M2L (SRAM A2), Brompton M2L(X), Dahon Uno (SRAM A2), Both Swift Xootr & Moulton TSR2 now gone

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