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  1. #1
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    Brompton M2L-X With E-Assist

    Just completed converting my new Brompton to e-assist.




    My previous M3L was converted as well but this is a new lighter 200W assist motor that only weighs 1.4kg. This brings the total carry weight (including motor) of my Ti Brompton to the same as a stock steel M3L i.e. 11.5kg.

    Older Tongxin Nano (2.1kg) and new Tongxin Goldant (1.4kg) motors side by side. The new motor is only 100mm diameter and looks barely larger than an dynamo. Both motors are around 80mm wide so you have to spread the 75mm wide Brompton forks a little, to slot it in.




    All the electronics and a smaller 1kg battery (good for 5-8 miles depending on terrain) are carried in the C Bag with an umbilical to connect it to the bike.









    My last conversion was throttle only whereas this one is pedelec (you have to turn the pedals to engage the motor). I tend to leave it off until I hit a head wind or an incline/hill. The Union Jack stickers reflect the current Jubilee celebrations in the UK!





    If you are interested in the build then full details are documented here

    I have been commuting daily for the last 2 & 1/2 years, 3600 miles total since 2009 on the original setup.

    Regards

    Jerry
    Last edited by jerrysimon; 06-06-12 at 04:12 AM.

  2. #2
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    This looks awesome, I need to replicate this. I had a go on a heavy e-brompton recently (the first electric bike I've ridden) and it put a massive smile on my face. I'm not a strong rider at all, largely as I have health issues to do with my spine, so I've had it in mind for some time that this type of thing will benefit me greatly.

    I see you cold-set the steel fork; did you have any issues fitting the hub in the ti fork?

  3. #3
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    Quote Originally Posted by chagzuki View Post
    I see you cold-set the steel fork; did you have any issues fitting the hub in the ti fork?
    Only my heart racing and sweat pooring down my face in terror as I did it.

    It wasn't so bad though, this motor being 80mm wide and having to spread the forks about 3mm further apart on each side. You have to actually spread them further as they sping back, more so with Ti!

    It was a risk but I have done it before on my Brompton steel forks. Harder on Ti forks and I may live to regret it, but hey you only live once. At worst it will cost me a new set of Ti forks.

    You also have to take a little "metal" off either side of the dropout for the larger motor shaft, about 1mm each side which was a challenge with Ti though my dremel did its work. I also modified the Brompton dropout washers/lugs to help maintain the secure wheel fixings.

    PS This rides unasisted much better than my 14Kg steel Brompton conversion and even that is light by most conversions I have seen!


    Regards

    Jerry
    Last edited by jerrysimon; 06-06-12 at 07:39 AM.

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