Gravel Dropper Post with Di2

One of my gravel bikes is set up with 2x Shimano Di2. I’d like to add a dropper post. Couple questions… One is how to accommodate the Di2 battery in the setup. Are there dropper posts with built-in battery carrier (have not come across any), or does one simply drop the Di2 battery down the seat tube to the bottom bracket, and then place the seatpost? Secondly, since I am running 2x, can one program the accessory buttons on top off the drops to activate the dropper post? My other gravel bike is built with SRAM AXS - obviously much easier to integrate a dropper post with this setup as compared to Di2.

I have no input regarding di2 battery placement.
I will just point you to the Magura Vyron Elect dropper post, it is wireless. I use that on my gravel bike. The trigger can easily be placed in the drops, as it uses rubber bands.
I works quite well.
Note the I’m running 1x, but that placement should work with 2x.


I put the battery in the fork steerer tube on my MTB. The other option is the down tube, if you can get to that.

You would probably have to take out the fork, and push the battery in through the head tube… not ideal. Or indeed put it in the down tube through the bottom bracket.
Both are not that great, since you’d have to remove the cranks/BB or fork if you ever need to get to the battery.

My MTB frame/handlebar were not really made for internal Di2 routing, so I made a small hole in one of the spacers and routed the wire through that:

And no, the battery hasn’t fallen out the steerer tube yet ;-). It’s pretty secure!

(here’s more on that battery holder: Install the Di2 battery in the fork steerer)

2x, can one program the accessory buttons on top off the drops to activate the dropper post?

Not as far as I know :frowning:

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Seems like Shimano need to make an electronically activated dropper post with an internal Di2 battery. An e-tube connector on the bottom would allow any Di2 bike an easy upgrade. Either configure the additional buttons in the levers or that useless left hand 1x shifter to control it…

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as we learned in the past decades - SHIMANO is not really on the fast lane in terms of “NEW” stuff or am I missing something here ???
There are beautiful buttons on the GRX Di2 hoods - left and right hand but so far they want you use your “where am I - how fast am I devices” with those and nothing else - :sleeping:

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You can use those buttons to shift, but yeah… the default function for those buttons is D-Fly Ch1/2… it’s a bit silly :frowning:

Can you please get a bit more specific - I would like to use those buttons as an alternative shift option - THANKS :blush:

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  • Download E-Tube Project 3.4.5 or 4.0.4 (ARCHIVE | E-TUBE PROJECT)
  • Use the charger to connect the bike to a Windows computer and run E-Tube Project.
  • (if ETP 4.0.4 complains that your BCR2 needs to be updated, run ETP 3.4.5 and it’ll auto update)
  • After you connect to the bike, use ‘customize’ to set up the buttons

How you do this depends on the E-Tube version you’re using. If you’re having a hard time finding the settings, here are two guides (written by me ;-))

E-Tube Project V4.0.4: Change button setup - enable buttons on Di2 shifter hoods
E-Tube Project V3.4.5: [E-Tube 3] Change Di2 shifter button assignments

way cool - THANKS :pray:

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I have Di2 on my gravel bike. I run a Di2 grx shifter on the right and use their auto shifting to shift the front derailer. On the left side I run the grx dropper post shifter. The shifters look pretty different since one is manual and the other Di2, but they actually feel really similar in use.

For the battery I use a battery holder that they make for mountain bikes that attaches to a water bottle holder. I have heard that you can put the battery in below a dropper post in the downtube, but this seemed easier to me.

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I’d be putting the battery into the seat-tube below the dropper past wrapped in bubble wrap so it won’t drop/rattle but so the dropper cable can come past it. Consider using an over-length bottom bottle cage bolt to act as a safety pin so it can’t migrate down onto your BB

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The cool thing about the SM-BTC1 is that is isn’t just a battery holder, it’s also a 5 (6 if you count the wire to/from the battery) port junction :).

I do dislike how chunky it is though… it’s quite big. Looks good on your bike, but on my Zwift bike it was installed using the down tube bottle mount holes - and it was quite in your face :slight_smile: