Extend 12-speed SW-RS801 Satellite Shifters

Updated September 3, 2023 by BetterShifting Terry

The 12-speed satellite shifters are pretty neat - they work by plugging them into the bottom port of the Ultegra and Dura-Ace shift levers (not 105), and they work right out of the box!

Sure, you can program them to perform other functions, but you generally don't have to.

Shimano makes three different versions of the SW-RS801 satellite shifter:

All of these shifters are essentially the same unit, the only differences are in the wire length and clamp size.

Two SW-RS801-T shifters, with the 31.8mm clamp and the 24mm clamp

These shifters only work when plugged into the bottom port of Ultegra and Dura-Ace shifters, and you cannot even plug them into a different port if you try. The connectors have alignment tabs that make sure you don't use them in a regular E-Tube port.

Why extend satellite shifters?

Most people who want to extend 12-speed satellite shifters want to use their sprint shifters on their clip-on aero bars. These shifters aren't cheap, and I get it. If you can use the same shifter in two different locations, why not? Also, the -E version of the SW-RS801 satellite shifter isn't available for purchase until late 2023.

Others want to use shifters in places other than the ones intended by Shimano.

Whichever the reason, you can definitely extend the satellite shifters. You can also use this method to connect two satellite shifters to the same shift lever. For example, a sprint shifter and a climbing shifter.

One method - splicing the wires

A while ago I thought the only method to extend satellite shifters was to splice the wires. This involves cutting the connector off of the satellite shifter wire, and stripping the outer housing and the two tiny inner wires.

While it can definitely be done, it's not recommended for novices. Cutting up Di2 wires, and soldering or crimping wires together can cause some strange Di2 issues.

No one wants to ride a bike that automatically shifts every time you hit a bump in the road.

Preferred method: use an inline junction

I love hacking Di2, but this doesn't always have to involve cutting up wires.

To extend the satellite shifters, I'll use the EW-JC302 inline junction.

Extend a satellite shifter, step by step

Before we get started, make sure you have these items:

Step 1: Unboxing

Take your shifter, junction, and wire out of their boxes. As you can see below, the alignment tabs prevent you from plugging the satellite shifter into the EW-JC302 junction.

This won't fit, the alignment tabs are in the way

Step 2: Cut the alignment tabs off

Use the knife to carefully cut off the alignment tabs.

Yes, really - cut them off! This will not impact the shifter's functionality at all, and this will make it fit into a regular SD300-type port.

While it looks nice in the photo, don't cut your tabs off like this

Again, be careful. Cutting off the alignment tabs won't harm the satellite shifter's functionality, but cutting off half of the connector definitely will.

Be sure to cut off only the alignment tabs.

Do not cut off more than required.

Either cut straight down or lay the plug on a flat surface and cut it that way.

Here's what happens when you cut too much off. This shifter still works just fine, but it isn't pretty. Take care.

Step 3: Plug it in!

That's it! You're done.

Plug the satellite shifter into the JC302 inline junction, and connect that EW-SD300 wire to both the inline junction and your shift lever.

Use the bottom port.

With the alignment tabs cut off, and with the satellite shifter extended using a junction and regular EW-SD300 wire, the satellite shifter now fits into any port on your shift lever.

However, ONLY the bottom port will work.

Only use the bottom port. Please.

Really. Don't even try to use one of the other ports.

The satellite shifters do not have any firmware or circuitry that'll let them function in any regular port. You must use the bottom port on the shift levers, and only the bottom port.

Your bike won't explode or catch fire when you plug these shifters into a regular port by mistake, by the way. The satellite shifters just won't work.

Don't do it :).

Multiple shifters?

I used EW-JC302 on this page, but you could also use EW-JC304. This junction has four ports, and it'll let you connect up to three satellite shifters to a single shift lever.

All you need to do is cut the alignment tabs off.

Two DYI satellite shifters

This is great when you want to use both sprint shifters and climbing shifters. Or when you want to build your own satellite shifters.

One little caveat though - all satellite shifters connected to a single port on a shift lever will perform the same function. You can not program them individually - the bottom port on a Di2 shift lever is just a dumb port.

Share your setups!

Have you extended your shifters? Or installed four or more satellite shifters on the same bike? Why? How?

I love reading about your hacks, and seeing them, of course! Leave a comment below, or send me a message or WhatsApp.

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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