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Drop bar brifter-actuated e-bike throttle

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    Drop bar brifter-actuated e-bike throttle

    The front derailleur is removed when installing the mid drive motor. With drop bars, this leaves an unused mechanism in the left shift/brake lever (“brifter”). The Bafang thumb throttle is intended for flat bars and does not fit on drop bars. This hack repurposes the brifter shift mechanism to remotely activate the thumb throttle.

    https://i.imgur.com/58IpRny.mp4

    Click image for larger version

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    Last edited by BattMan; 03-11-2020, 08:31 AM.

    #2
    This was made using spare parts in my garage:
    Bafang thumb throttle
    Accessory bar extension
    Barrel adjuster
    Presta valve nut
    Cheap reflector
    Shift cable and housing
    Cable lock nut



    I removed the reflector and kept the mounting bracket to use as a cable stop. This bracket uses M5 screws and nuts, so it would have worked with a shift cable barrel adjuster from a rear derailleur. I only had this brake barrel adjuster with M6 thread, but luckily the nut outer dimension matched the bracket. I added a round nut from a presta valve stem as a lock nut.

    Click image for larger version

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    Click image for larger version

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    I drilled 2 holes in the thumb throttle lever to connect the shift cable to the throttle. This let me route the cable up to the lever and push the loose end back out the bottom. The cable length is secured with a lock nut under the lever.

    Click image for larger version

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    Last edited by BattMan; 03-11-2020, 12:13 AM.

    Comment


      #3
      This build is nice! I'm in progress of setting up a gravel bike.

      How do you like your set-up?
      Any changes you would recommend to your build?
      How is the throttle control?



      Last edited by rickhap; 03-27-2020, 05:12 PM.

      Comment


      • BattMan
        BattMan commented
        Editing a comment
        The shifter mechanism lets me lock the throttle, like cruise control. This 2 speed shifter has 4 positions (like half shifts to match the deraileur cage to the chain line), so it can cruise at partial throttle.
        I added brake sensors to interrupt the throttle if I touch the brakes.
        I accidentally touched the throttle when I was not on the bike and it ran away without me. So, that is a problem. I can't let anybody borrow this bike - it will cause a crash like those Toyotas with the stuck accelerator pedals.
        I think I will open up the mechanism and remove the pawl to eliminate the cruise control feature.

      #4
      Wow, this is outside the box! Stumbled on this looking for an extension cable for the thumb throttle and learned it would never fit on a drop bar. Great idea repurposing the front shifter.

      Comment


        #5
        BattMan hasn't been on the forum for a while but I do like his idea. Even before he said it I wondered about at least combining it with a cutout to reduce the chance of runaways.

        Comment


          #6
          Very clever and clandestine too.
          "My favorite childhood memory is Having Energy” -Libby Harper

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