In-depth guide on upgrading your old Di2 bike

Updated January 22, 2024 by BetterShifting Terry

There are plenty of reasons for wanting to upgrade your old Di2 bike to a more modern setup. People have contacted me for advice on upgrading their bikes for the following reasons:

  • Upgrade 11-speed to 12-speed Di2
  • Upgrade from Ultegra 6770 10-speed Di2 to 11-speed Di2
  • Replace broken parts and upgrade at the same time
  • Enable Synchro-Shift by upgrading derailleurs/battery
  • Improved shifting and ergonomics
  • Tidy up wire routing and improve your bike’s aesthetics

I could go on because the list is virtually endless. Whatever your reasons, this page should answer any upgrade-related questions.

No 7970 - sorry!

Unfortunately, the DURA-ACE 7970 series as released in 2009 cannot be combined with modern components. You could of course replace every component on your bike, but that would be costly - and not what this page is about.

The 7970 series was Shimano’s first Di2 road bike series and when they released Ultegra 6770 in 2011 they made some changes that render the DURA-ACE 7970 hardware incompatible with any newer Di2 hardware. This is most obvious when looking at the plug. The older 4-wire system isn’t compatible with any current (2-wire) E-Tube component - you simply cannot connect them to each other.

EW-SD50 vs 7970 plug

If you would still like to upgrade your 7970 bike however, have a look at the Building a Bike guide that lists the components you need to build a modern Di2 bike.

Chain and cassette

If you upgrade your bike from 10-speed to 11-speed Di2, or upgrade from 11-speed to 12-speed, then you can generally keep your current crankset. Sure, the chain line is different for 12-speed Di2 (44.5mm vs 43.5mm), but that isn't a huge difference - and one that can usually be overcome by pushing the crankset out 1mm.

You will need to change your chain and cassette to match the derailleurs you're using though.

It is not possible to use 11-speed Di2 with a 10-speed cassette or chain. You also cannot use 12-speed Di2 with an 11-speed cassette/chain... except for ERG mode on your indoor smart trainer.


Knowing about the basic Di2 components and terminology will help you understand the concepts explained on this page. If you feel something is missing here please let me know.

  • Junction A: The junction box at the front of the bike. Either below the stem, handlebar drops or the downtube. Usually a display on mountain bikes. Has a button, LEDs and a charging port.
  • Junction B: A “dumb” junction box that connects the rear (FD, RD, battery) to the front of the bike. Basically a 4 way splitter. SM-JC41 is the internal version, SM-JC40 the external one.
  • D-Fly / Wireless unit: Enables BluetoothLE / ANT on road bikes. Current generation units are the EW-WU111 (mounted near front of the bike) and the EW-WU101 (mounted near the rear derailleur). The mountain bike displays also feature the same connectivity. These are optional. Not standard.
    Note: the older SM-EWW01 is also called “D-Fly”. This doesn’t support BluetoothLE however, only private ANT (so it will not connect to your phone).

6770 Di2 with external battery

Different reasons for upgrading your Di2

Depending on the reasons for upgrading your bike you’ll need to replace different things. Instead of writing one generic bit of text that covers everything only so-so, I’ve taken the time to write an in-depth guide for each of the scenarios. If you think one is missing please just send me a message and I’ll update and tweak this page as needed.

The scenarios covered on this page are:

I’ll also talk about other upgrades you can do such as installing a Wireless Unit and internal batteries vs external battery mounts.

If you want to skip ahead just click any of the links above to go to the corresponding section.

The most important tool - Di2 Compatibility Charts

When it comes to figuring out what components will actually work with your other components the Shimano E-Tube Compatibility Chart is invaluable. This document lists all E-Tube Di2 components (so no 7970).

Using it is simple - you find the right page depending on your battery or battery mount and then try to connect the boxes. If you can connect all the boxes by following the lines, your selected components will work together.

E-Tube compatibility chart

The latest E-Tube Di2 compatibility charts can always be found on the E-Tube Project Website Be sure to read the notes at the bottom of each section, because sometimes there are limitations depending on the selected components.

Quick note on upgrading to 12-speed

Since Shimano has just released their 12-speed Di2 groupsets, I thought I'd update this page with a little bit of information on that. A lot of users are interested in upgrading their existing 11-speed Di2 groupsets to 12-speed Di2.

Unfortunately, it's not as easy as just replacing the two derailleurs as you could before. This is mainly because the 12-speed components are not compatible with 11-speed shifters at all.

At the time of writing, you'll need to upgrade every Di2 component to 12-speed, otherwise it just won't work. You can use your existing 11-speed crankset though, if you really want to.

I will revisit this subject in a separate page, when the 12-speed dust has settled a bit.

Upgrade 10 speed Ultegra 6770 Di2 to 11 speed Di2

With the exception of the DURA-ACE 7970 series Di2 Shimano have actually been pretty good with regards to backwards compatibility. This means that it is relatively simple to upgrade an Ultegra 6770 10 speed bike to 11 speed Di2.

The bare minimum you need is two new derailleurs.

That’s it.

Upgrade 6770 to r8050

Yes, it really is that simple. There are some caveats, of course - but if you want to spend the least amount of money and still upgrade your Di2 bike to 11 speed then that’s all. Just buy two 11 speed derailleurs and you’re done - and replace the chain and cassette, of course.

Now if I were to upgrade a 10 speed Di2 bike to 11 speed Di2 I would also take the opportunity to upgrade some other parts, but we’ll get to that later. First let’s have a look at upgrading the derailleurs.

New Rear Derailleur and Front Derailleur

As you may have seen in the compatibility charts above, almost any combination of components will work. In this section I’m assuming you have an Ultegra 6770 setup the way it was originally produced - with the SM-BTR1 external battery and either the SM-BMR1 or the SM-BMR2 external battery mount.

This is the Di2 10 speed setup we’re upgrading to 11 speed:

Let’s take a look at the compatibility charts. Scroll down to "DI2 with SM-BMR1/SM-BMR2/SM-BTR2". At the time of writing this is page 3 of the PDF file.

Start at the top and follow the lines connecting the ‘Master Unit’ (battery/mount),Junction A and Shift units, until you get to the derailleurs. You’ll see that the line splits into 10 speed on the left and 11 speed on the right.

Di2 compatibility charts page 3

Note that once you’ve selected a 10 speed rear derailleur you cannot combine that with an 11 speed front derailleur. It is the same the other way around - you cannot combine a 10 speed front derailleur with an 11 speed rear derailleur.

Just in case you were thinking of only upgrading the rear derailleur and keeping your existing 10 speed front derailleur - it probably wouldn’t work. I say probably, because originally this worked just fine. At some point Shimano determined that using a 10 speed front derailleur and 11 speed rear derailleur did not provide the user experience they wanted and they disabled this in a firmware update.

So yes… if you never ever update the firmware on any of your components and find an 11 speed rear derailleur with really old firmware then you can use that with your existing 10 speed front derailleur. But really, save yourself the hassle and just upgrade both derailleurs.

What derailleurs should you get though? The good news is that you can use any 11 speed Di2 road or grx derailleur. You cannot use a mountain bike derailleur with a road derailleur, but mixing road and grx works just fine. Once again though, Di2 components from the same series have been designed to work together and will work better than using a road front derailleur with a GRX rear derailleur for example.

Old 6770 derailleur vs new R8050 rear derailleur

Personally I’m a big fan of the R8050 derailleur - the short cage version will accept cassettes up to 10-30T which is pretty good for most of us. They’re also a bit more flexible than the 6870 series derailleurs when it comes to synchronized shifting.

You can keep your existing 6770 shift levers if you want. You can even keep that SM-EW67A-E junction box and your old external battery and battery mount. They will all work with newer Di2 derailleurs.

If you want to use synchronized shifting by the way, do read the section on Synchronized Shifting - it explains the bare minimum synchronized shifting requirements.

About those caveats..

However, if you rush off to your favourite webshop be aware that even though the compatibility charts state that these components will work together, they may in reality not work at all when you install them.

You may be required to update the firmware on your old components.

Since the bike setup we’re talking about here uses the SM-EW67A-E Junction you cannot just connect the bike to a Windows computer and update the firmware - there is no way to connect this bike to your computer. The firmware on an SM-EW67A-E bike can only be updated using the SM-PCE1 / SM-PCE02.

These units are relatively expensive and most consumers will have no use for them. They only do diagnostics and do not charge the bike. It is therefore a good idea to ask your local bike shop whether or not they have one of these units and what it’d cost to update the firmware on your bike.

The SM-BMR1 is a bit of a special case. An old E-Tube manual mentions that the battery should be disconnected from the SM-BMR1 battery mount and that it should be updated using the SM-PCE1.

Also, when someone brought me a crashed or “bricked” SM-BMR1 I could not restore it using my SM-PCE02. I spoke to Shimano about this and they suggested using the older SM-PCE1 instead - and this indeed managed to restore the battery mount firmware. I therefore recommend not updating the SM-BMR1 if at all possible. If you do have to update the battery mount please get a friendly bike shop to do it for you.

Note: upgrade the rear derailleur only - if you're feeling adventurous

So... it is actually possible to upgrade your bike to 11 speed by just upgrading the 6870 rear derailleur. However, as you've read above, Shimano has blocked this in firmware. If you're brave and feel like downgrading the 6870 rear derailleur to firmware version 2.5.2 then you can use the RD-6870 with an FD-6770. Keep in mind though that you will never be able to upgrade your RD-6870 firmware - if you do, the bike will stop working until you upgrade the front derailleur.

You can read more about downgrading firmware in this forum thread or Carlton Bale's page.

Upgrade to Enable Synchro-Shift

Synchronized Shifting is available on road bikes, mountain bikes and also on Shimano Di2 gravel bikes - the GRX Di2 series.

While road and grx are the same ‘category’ to E-Tube Project, mountain bikes are a category all on their own. You may not care about the ‘category’ your bike falls into and rightly so, but this isn’t just about semantics - the synchronized shift requirements are different for road/grx and MTB.


In order to use Synchronized Shifting on Road/GRX bikes you need any two of these derailleurs:

You will also need a modern battery or battery mount. Those originally released with the 6770, 6870 and 9070 series won’t do.

BT-DN110 battery

If you’re using an internal battery this should be the BT-DN110. The older SM-BTR2 will NOT work. Does your bike use an external battery? In that case you will need the external battery mount BM-DN100.

SM-BTR1 and BM-DN100

Of course you could also upgrade your external battery mount to the internal battery, but keep in mind that it is not a simple battery swap. In that case you also need:

Do you have an SM-EW67A?

If you upgraded a 6770 Di2 bike to 6870 or newer it is possible that you still have an SM-EW67A-E junction installed. This isn’t compatible with the BT-DN110 or BM-DN100, so you’ll have to upgrade that too.

This is not a bad thing - the modern junctions SM-EW90 and EW-RS910 not only allow you to charge batteries (internal only), but also change settings and update firmware using a Windows computer and the SM-BCR2.

Mountain Bikes and Synchronized Shift

Synchronized Shift has been available on mountain bikes long before the BT-DN110 internal battery or BM-DN100 external battery mount were released. The Synchro Shift requirements for mountain bikes are therefore a bit more complicated.

MTB riders

You don’t necessarily need a new battery or mount, but a display is required.

Each of these combinations will enable Synchronized Shifting.

  1. SC-M9051 / SC-MT800 + BT-DN110
  2. SC-M9051 / SC-MT800 + BM-DN100
  3. SC-M9050 + BT-DN110 / SM-BTR2
  4. SC-M9050 + BM-DN100 / SM-BMR1 / SM-BMR2

Looking at the list above, 1) and 2) enable wireless connectivity using BluetoothLE. Because of this the SC-M9051 and SC-MT800 will not work without the BT-DN110 or BM-DN100.

The older SC-M9050 as used in 3) and 4) does not feature wireless connectivity and therefore can be used with any battery or battery mount.

It’s not just about hardware - firmware updates

Depending on the components you’ve installed and when you last updated them you may also have to upgrade your firmware. In some cases the newer firmware enables features like synchronized shifting - on the 6870 and 9070 series for example.

In other cases updating your firmware is required to make the components “see” each other - the bike simply won’t work without updating firmware.

RD-R8050 firmware updates

Do you use an external battery? Then you probably do not have the SM-BCR2 internal battery charger or one of the SM-PCE units. This means that you cannot update firmware yourself. In this case it can be worth it getting the local bike shop to do your upgrade or buy an SM-BCR2 or SM-PCE02 yourself.

Note on Synchronized Shifting using 6870 / 9070 series

If you’re thinking of upgrading your bike to the 6870 or 9070 series, consider getting a newer front derailleur instead. The FD-6870 and FD-9070 limit the flexibility of synchronized shifting setup in a strange way. The point at which the bike shifts from the big to small ring can only be set to the last two sprockets or cogs on the cassette (the easiest gears).

This means that you will encounter some cross chaining before the bike automatically shifts from the big to the small ring.

When I first ran into this limitation I tried every possible combination of E-Tube settings and even swapped out my RD-6870-GS for an RD-6870-SS - it made no difference. It wasn’t until I got my hands on R8050 series derailleurs that I realised that the limiting factor was the FD-6870.

The image below describes this better than I can:

Synchro shift 6870 vs r8050

What you’re looking for are the white boxes underneath the ‘50T / Top’. These are the gears you can move the light blue coloured box to - this is the gear at which the bike will shift from the big to small ring.

Readers have confirmed that the same is the case for the 9070 series. When you use FD-R9150 or FD-R8050, you can select the shift point from a much wider range of gears.

Whether or not the cross chaining is enough to put you off (full) Synchronized Shifting is up to you. It is at the very least something to be aware of.

Upgrade your bike’s looks and improve wire routing

With the focus on aerodynamics and clean looking bikes lately people have been trying to greatly reduce the amount of visible cables on their bikes. Shimano’s Di2 flexibility lets you easily upgrade your older components to make your bike’s cockpit area a little cleaner.

There are several ways to do this, so let’s discuss each on its own. It’s up to you do decide whether or not each of these is worth implementing on your bike.

Swap that external battery for an internal BT-DN110

While this isn’t possible on every bike, moving from an external to an internal battery is definitely at the top of my list when tidying up a bike. External batteries are usually located either underneath the bottom bracket or mounted to one of the bottle cages.

Swapping it out for the internal battery isn’t as simple as just buying the battery - there’s quite a bit more to think of and it’s relatively expensive. Still, this way you not only improve the way the bike looks, you’re also adding a PC interface to the bike.

Keep in mind though that this will only work if there is a way for the Electric Wire connecting the battery to enter the frame. Di2 wires are only 2mm in diameter, but the plug itself is 5mm.

Di2 plug diameters

If you are unsure whether or not this will work on your frame consider buying just one EW-SD50 to try this out with the real thing.

First of all, moving the battery to a new location will require at least one new and longer EW-SD50 Electric Wire. If your bike allows you to hide the SM-JC41 junction B in the frame then you might as well do that too. The SM-JC41 is just a four way splitter and it is relatively cheap. Keep in mind that you may need longer Electric Wires here too though.

Charging your brand new internal battery can only be done through the Junction A. Any Junction A will do, except SM-EW67A-E - this doesn’t have a charge port. Installing the SM-EW90 / EW-RS910 or SC-MT800 / SC-M9051 will also allow you to connect your bike to a Windows computer using the charger - the SM-BCR2. Yes, you’ll need to buy a new charger too.

Finally, securing the battery in the seatpost can be done using bubble wrap or a piece of cloth - my preferred way is to use a Di2 seatpost battery holder.

Replace your SM-EW67A

While it is completely possible and valid to use the SM-EW67A junction with an R9150 setup, this junction has seen better days. Nowadays you should really be using at least the SM-EW90 or EW-RS910 on road bikes and a display on mountain bikes.

Upgrade SM-EW67-A

Not only do these newer junctions allow you to charge internal batteries, they also let you use synchronized shifting and connect your bike to a computer.

The SM-EW67A-E was originally designed as an OEM part, allowing bike shops to quickly build a Di2 bike using standard components. To make things simpler it came with three electric wires built into the junction.

If you are replacing yours with a newer junction keep in mind that you will also need two or three new E-Tube electric wires - to both shifters and junction B.

Eliminate the EW-JC130 Y-splitter

Most modern road bikes come with the handlebar/frame junction EW-RS910 installed - and usually the EW-JC130 Y-splitter cable as well. This makes sense, because this is how Shimano describes the cockpit setup in their dealer manuals. Also, it’ll give you the greatest amount of spare E-Tube ports - in case you ever want to install two extra shift buttons for example.

The EW-JC130 is connected to the left shifter and the EW-RS910 junction and then runs all the way to the internal Junction B using the inline junction EW-JC200 and a long EW-SD50 wire. Again, this setup makes sense for most people. That EW-JC130 and EW-JC200 look a bit bulky however.. and if you do not need more than one spare port there is a way around them.

EW-JC130 sizes


It is important to remember that the Di2 system itself does not care how it is connected. As long as components are connected to the rest of the system, they will work. This alternate setup uses that flexibility to tidy things up a bit.

The left shift lever has two E-Tube ports. Use the top port to run a 450-600mm long E-Tube wire to the top port of the right shift lever. Now connect the right shift lever to the EW-RS910 using a 150-250mm long E-Tube wire. Using the other port on the EW-RS910, run a single EW-SD50 Electric Wire to your internal junction B. This wire will be about 900-1200mm long.

Not sure about wire length? Read this page on selecting the correct Di2 wire length for your bike.

You have now connected both shifters to each other and connected those to the handlebar junction. That junction then connects the shifters to the rest of the bike. This effectively removes both the EW-JC130 and the EW-JC200 from the setup.

Downside of this method? You only have one spare E-Tube port - the one on the left shifter. If you want to connect the SW-R9150 satellite shifters you’ll need two ports. Also, in my opinion this method works best if you can run the electric wire from left to right shifter through the handlebars. Otherwise you’ll still have an exposed wire running along the handlebars.

Hide your EW-WU111 Wireless Unit

Shimano’s dealer manuals state that the EW-WU111 Wireless Unit should be installed outside the frame - usually between the EW-JC130 and the Junction B. Because it is essentially the same size and shape as the EW-JC200 inline junction that’s already installed on most modern bikes this makes sense, it is a simple swap.

Comparison of EW-JC200 and EW-WU111

If your bike doesn’t use the EW-JC130 / EW-JC200 though, where would you put the EW-WU111? You could install it between the SM-EW90 junction and a shifter using a 150mm electric wire, or between Junction A and Junction B.

Neither of these methods is ideal - they both add an extra unit to the front of the bike and I personally don’t like the way this looks.

Instead add the EW-WU111 to your handlebar drops. You do not have to connect both ends of the EW-WU111. It is perfectly fine to connect just one end of it and leave the other side disconnected. It will work just fine.

If you do not have the EW-RS910 installed in your handlebars you can install the D-fly to either the left or the right side (drop). Do you have the EW-RS910? Then either install the Wireless Unit on the other side or install it inline between the EW-RS910 and the shifter.

And yeah.. the Shimano dealer manuals state that the EW-WU111 must be installed outside the frame - doing otherwise could cause bike computer signal loss issues. The drops are so close to your bike computer however that this will work without problem - I have never heard of issues when the D-fly is installed here.

Some people put the EW-WU111 in the seatpost. While this may work in most cases, keep in mind that it was intended to be installed outside the frame and that the distance between seatpost and bike head unit is much greater than that between drop and head unit.

Which Junction? SM-EW90-A vs SM-EW90-B

Have you decided to install an SM-EW90 Junction A? If you’ve already checked your favourite web shop for prices you may have seen that there are two versions of the SM-EW90 below-the-stem junction: the SM-EW90-A and SM-EW90-B.

The difference is in the number of E-Tube ports on the junction. The SM-EW90-A has three ports while the -B version has five ports.

SM-EW90-A and SM-EW90-B junctions

So which one do you need?

Generally speaking the three port SM-EW90-A will do just fine. It depends on the amount of shifters you want to install and the amount of ports you need. Keeping in mind that each shift lever has two E-Tube ports (except ST-R785, they have just one) and some have a dedicated sprint shifter port, a three port SM-EW90-A should be enough for most road bikes.

Time Trial bikes tend to not use traditional STI levers and each TT shifter has only one E-Tube port. For this reason it makes sense to install the SM-EW90-B on Time Trial bikes - you simply need the extra ports to connect four shifters.

This doesn’t mean you cannot use the EW-RS910 on TT bikes of course - people use that as well. They tend to add one or two SM-JC41 junctions to the base bar or stem to add more E-Tube ports to the system. The SM-JC41 is just a “dumb” four-way splitter and you can have as many of those as you like.

If you go this route your biggest challenge would be to find a way to secure the extra SM-JC41 junctions somewhere out of sight.

I hope this guide helped you upgrade your older Di2 bike to a more current setup. Of course feel free to send me any questions - that’s what I’m here for!

Also take a look at the pages on selecting the right Di2 wire length and the Di2 installation guides.

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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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