Build your own cheap Di2 satellite shifters (DIY)

Published January 20, 2023 by BetterShifting Terry, Last updated January 24, 2023

If you've ever looked online for Di2 satellite shifters you will have no doubt seen the price tag. More than $ 100 / € 100 for a pair of satellite shifters? Ouch!

Sure, they're great quality and guaranteed to work… but they're costly. Did you know that you can actually make your own? Your own homemade, DIY Satellite shifters? At a relatively low cost?

All you need is any dumb button or switch and an EW-SD300 (12-speed) or EW-SD50 (11-speed) wire.

Not for 11-speed Disc

Before we start, I need to apologise to 11-speed disc riders (ST-R8070 / ST-R9170 / GRX). The method described here will only work on 11-speed rim brake bikes and 12-speed Ultegra and Dura-Ace road bikes.

Why? Well, the 105 disc shift lever and the 11-speed disc brake shift levers do not have the required satellite shifter port. These shifters only have regular SD50 / SD300 ports, and any component you plug in there needs Di2 firmware (and thus a PCB) to register on the Di2 CAN-based network.

How does this work, exactly?

The great thing about satellite shifter ports is that they'll accept any simple switch. In fact, regular Di2 components will not work in those ports. Only satellite shifters.

Every 12-speed shift lever has one of those satellite shifter ports, and the 11-speed rim brake shifters do too. This is always the bottom port.

E-Tube ports on a shifter

And yes, it looks different. Satellite shifter connectors have little 'tabs' or 'fins' on them to make sure you do not plug a Shimano satellite shifter into a regular Di2 port.

I know what you're thinking, but don't worry. You can plug a normal SD300 or SD50 wire into a satellite shifter port just fine. We'll take advantage of that to hook up the DIY shifter to the rest of the system.

What buttons to buy

Let's discuss the parts you need in more detail, starting with the buttons.

First, the buttons or switches. Any momentary switch will do. Ideally waterproof or at the very least water-resistant. Even if you do not intend to ever ride your bike in the rain, I bet you do wash your bike every now and then.

This will be the main part of your satellite shifter, so make sure you get it right.

Buttons online

Unless you plan on installing another battery, make sure the button you buy does not require power for an LED or a light. Any basic two-wire button will do, there's no need to make this any more complicated.

Di2 wires

The next part you'll need is a Di2 wire. If you're building this shifter for use with an 11-speed bike you'll need an EW-SD50 wire. Is yours a 12-speed bike? Then you need an EW-SD300 wire.

One single wire has two plugs, one at either end. Cut that wire in half and you'll end up with two wires that you can connect to your buttons

As for the wire length, that's up to you. It also depends on the shifter placement. For this project, I decided I wanted to put a shifter in the handlebar drop and went with a 600mm wire,

I figured that this would let me make two 300mm satellite shifters, and that 300mm would be more than enough.

I was wrong.

Now… this isn't a huge issue, because I can extend the wires using regular electrical wire, but save yourself the trouble - make sure the wire you buy is long enough.

You can tuck away excess wire in the frame or handlebar, or hide it underneath the bar tape. Long wires cost the same as shorter ones, so there's no cost-saving benefit there either.

Buy the wires at your local bike shop, or, if you want to support the site, use one of my (affiliate) links:

Building the satellite shifter

With that out of the way, let's build the actual shifter. The process is really simple.

  • Cut your E-Tube wire in half
  • Strip the wire and expose the inner wires
  • Connect the wire to your button/switch

Tools?

You can do this without tools if you really want to, but there are a couple of things that make life a lot easier.

I recommend using a decent wire stripper to, well, help strip the wires. They're pretty tiny and you'll need all the help you can get.

Depending on the button you've bought, you may also need a soldering iron to join the wire, and heat shrink tubing to secure and protect the joined wire.

Here are the tools I used:

Cut the E-Tube wire and expose the wires

Take your Di2 wire out of the box if you haven't already, and cut it in half. A pair of scissors or other cutting tools will do.

SD300 wires cut in half

Now get that wire stripper out and take off the black outer layer. I took about 30mm - 40 mm off so I could comfortably strip the inner wires. I recommend doing this in a two-step process, rather than taking the entire length of the outer layer off at once.

The inner wires are 0.9mm in diameter, and you need to be careful not to damage them.

Don't have a wire stripper? Take a sharp knife and carefully cut away the outer layer. This may take a couple of tries, but can be done. Some people actually prefer this over using a wire stripper.

Inside you'll find two very small inner wires:

E-Tube wire inside

Next, you'll need to expose the strands of the inner wires. You can either use a wire stripper or use your fingernails or knife. Each wire is made up of 36 smaller wires (strands).

SD300 and SD50 wire inner wires

The strands will probably come untwisted as you strip the inner wire, so twist them back to form a single wire again.

If your button lets you connect the wires to it directly then you're pretty much done at this point. Simply connect the wires to your button and you're ready to test whether or not your creation works - shifts the bike.

Here's an example where I could connect the wires to the button using the button's connectors.

DIY shifter button : Other buttons and switches come with wires attached to them and usually require you to join your E-Tube wire and button wire together.

There are a couple of ways to do this, but the most popular seem to be soldering and crimping. Since I have a soldering iron that I hadn't used for a while I decided to give soldering a go. I did the same when I added 7972 satellite shifters to my commuter bike.

Button and E-Tube Wire

I'd love to show you images of both methods, but my soldering "handiwork" probably isn't the best example to learn from. Instead, here's a video that explains both methods in more detail.

Waterproofing

It makes sense to add some protection against the elements. No one likes glitchy shifting or ghost shifts.

The most basic (and cheap!) protection you can add is heat shrink tubing. It shrinks when heated, causing a tight seal around the wire.

Before I soldered the wires together and made a permanent join I slid some heat shrink tubing over the two inner wires, and a larger one over the wire's outer layer. This way my wires are protected, and won't accidentally touch and cause ghost shifts.

There's "regular" and waterproof heat-shrink tubing. Naturally, the waterproof version is preferred - all bikes get wet at some point.

If your E-Tube wires connect to the button directly, I'd also protect that area. Heat shrink tubing is one method, but my preferred solution is to use epoxy resin to create a robust, waterproof area around the connectors. At the same time, this will also protect against pulling the wires loose.

And yeah, these won't do you any good if your button isn't waterproof - as you can see in the video at the bottom of this page.

Set up and test the buttons

Chances are pretty good that your buttons will work out of the box, but if they don't then they're probably disabled in the software.

If you're on 11-speed Di2, connect to the bike using the charger and a windows computer.

You can change the satellite shifter button assignments through the customize page. Open the shifter properties and make sure the satellite shifters are enabled. This is also where you can change the shifter function.

E-Tube Project

Do you have a 12-speed Di2 bike, or 11-speed with the D-fly? Then simply connect to your bike using the mobile app.

Again, open the customize page and tap the shifters to customize them and their button assignments.

E-Tube Cyclist

Want to know more about changing your Di2 button settings? I've published a page on just that right here: Change Di2 button setup.

More! More!

Did you know that you can connect more than one of these satellite shifters to each satellite shifter port? You cannot program them individually, so they'll all perform the same function, but this is a great way to have satellite shifters on both the tops and the drops.

How? Simple! Connect them to a four-port junction (EW-JC304), and then run a single wire from that junction to the satellite shifter port.

Di2 shifter with two satellite shifters

You can do this with regular Shimano satellite shifters too, but you'll have to cut the little tabs/fins off the connector.

Build your own

That's it! You should now be able to build and set up your own DIY shifters. I'd love to see what you can come up with. Please share your creations in the comments below, or tag me on Instagram (@BetterShifting).

Any problems? Questions? Ask me anything.

BetterShifting Terry

About the Author - BetterShifting Terry

I enjoy playing with bike tech - both bike building and wheel building, bike maintenance and of course, Di2. Besides writing content and working on the technical side of BetterShifting, I also work as a Software Developer in The Netherlands. Read more on the About this site page.

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