12-speed Dura-Ace, Ultegra, 105, GRX Di2 and 11-speed Di2 compatibility

Updated June 20, 2024 by BetterShifting Terry

With the release of Shimano’s 12-speed DURA-ACE R9200, Ultegra R8100 Di2, 105 Di2, and 12-speed GRX RX825, I’ve been getting a lot of questions on compatibility.

Especially backward compatibility.

Can you use 11-speed components with the new 12-speed Di2 series, and if so, which?

Is there an easy (cheap) upgrade path?

If you’re anxious to know the answers to these questions, I'll get straight to the point:

Yes, some of the 11-speed components are compatible… but no, there is no cheap and easy upgrade path.

Skip ahead

Let’s take a closer look at each of these topics. If you'd like to skip ahead, use these links:

Can you use 11-speed Di2 components with 12-speed Di2?

Since the new 12-speed groupsets use a different wiring standard you might expect the answer to this question to be a resounding no, but it’s not that simple. You see, Shimano made an EW-SD50 to EW-SD300 adapter, the EW-AD305.

ew-sd300 to ew-sd50 using EW-AD305

This adapter connects an older EW-SD50 wire and a new EW-SD300 wire to each other, allowing you to connect SD50 components to SD300 systems (or the other way around, of course).

For example, the EP8 drive unit features two SD300 ports, but it is compatible with SD50 type shifters and displays through the use of the adapter.

However, and this is a big one, the components you connect to a Di2 system need to have firmware that will let them communicate with the other components.

Without updated firmware, the bike simply won’t work.

Not all 11-speed Di2 components have gotten a firmware update to make them work with 12-speed drivetrains. In fact, only a few have.

The compatible components are:

If you’ve clicked the links to the component pages you have probably noticed that most of these have one thing in common: they’re all time-trial shift units. All, except the SW-R9150 sprint satellite shifter.

Shimano has decided against making EW-SD300 versions of the time-trial shifters and instead chose to update the older units’ firmware to make them work with the 12-speed systems. This way you can build a 12-speed Di2 Time Trial bike, but you’ll have to use the EW-AD305 adapter to connect your shift levers.

Also, these shifters have to be connected to the BT-DN300 battery by wire. They will not function if there isn't a wired connection between them and the battery.

You could plug them into one of the wireless shift levers, but they won't work unless you then connect the shift levers to the battery by wire.

Why are these units compatible?

So why are there are no new EW-SD300 versions of the time-trial shifters?

There are a couple of reasons for this.

First, the high-end time-trial Di2 market isn’t exactly huge. Only a very small percentage of riders use Di2 and an even smaller portion of that is into time-trialing.

Second, there was a global shortage in the bike industry at the time of release, and resources are scarce. When you have a lead time of months on simple parts like cassettes and chains it doesn’t help to add yet another new product to the manufacturing lines.

Also, Shimano and their dealers may simply be sitting a large stock of TT shifters they want to get rid of first.

Shimano has not ruled out there ever being EW-SD300 TT shift units – they’re just not making them at this time. In fact, I’m confident that they will make them at some point, probably in a year or two.

SW-R9150 - that's not a Time-Trial shifter!

So, if Shimano has chosen to make only TT shifters compatible, what is the SW-R9150 satellite shifter doing in this list?

This probably has something to do with some users - both consumers and professionals - wanting to use multiple satellite shifters. In the drops and on the top of the bar for example. Or having sprint shifters in the drops and a climbing shifter on the handlebar main section.

Multiple satellite shifters (Image by BikeWorldNews.com)

The 12-speed SW-RS801-T/S satellite shifters plug into a dedicated sprint shifter port, and each 12-speed Di2 shift lever only has one of those ports. So what do you do when you want to connect more than two satellite shifters?

You can either use multiple SW-RS801 shifters connected to the same port, or you can use the EW-AD305 adapter and the SW-R9150 sprint shifter.

Is there a low-cost 11-speed Di2 to 12-speed Di2 upgrade path?

Unfortunately no, there is not.

As I’ve mentioned above, 11-speed Di2 components need a firmware update to make them work with 12-speed Di2. None of the R8050 / R9150 components have gotten that update, except the ones listed earlier.

So no, you cannot just upgrade the derailleurs and battery and keep your current 11-speed shift levers. The system won’t work. It won’t shift.

This is a bit of a bummer since Shimano Di2 has been pretty good with regard to backward compatibility in the past. You can use 10-speed 6770 Ultegra (2011) shifters with 11-speed R8050 Ultegra (2017) Di2, for example.

Don't just take my word for it - take a look at the recent firmware updates on the E-Tube site, or read the Shimano Di2 Compatibility information yourself.

Why? Is Shimano in it for the $$$?!?

First of all, Shimano is a company, not a charity. Companies do exist to make money, strange as it may sound :).

However, that’s definitely not the main reason for breaking the compatibility with older components.

At some point, it is time to say goodbye to the EW-SD50 wiring standard and its components. Shimano decided this time is now, and I can’t blame them.

Having to keep the older components compatible requires periodic work. Not just the software maintenance, updates, and bug fixes, but also testing them - making sure they actually work.

If a component is listed as ‘compatible’ in the E-Tube compatibility charts, you can count on that being compatible. Fully tested and all.

11 speed shift units compatibility

For the 10-speed and 11-speed Di2 series, the compatibility charts list a massive 50 shift units. That’s ‘only’ 28 if you consider the left/right versions to be the same.

The 12-speed series shift units box contains only 16 compatible units, or 9 if you ignore left/right versions.

12 speed shift unit compatibility

And sure, you could argue that all the shifters do is “send a shift signal, how hard can it be?”. Or that Shimano could’ve simply updated the firmware on the previous generation components (R8050 / R9150), or all 11-speed components, or anything else.. but you have to draw the line somewhere.

Personally, I’m happy that there will never be hundreds or thousands of bikes mixing EW-SD300 and EW-SD50 parts. Except for those couple of time-trial bikes and four-satellite-shifter bikes, It’s either EW-SD300 or EW-SD50.

That’s going to make my life a lot easier too.

What if your 11-speed parts break?

There is a two-year warranty (three on DURA-ACE / XTR) on Di2 components, and Shimano will have to honor that. Shimano will keep producing the mechanical and Di2 R8000 and R9100 series components for a while, but gradually their manufacturing focus will shift to the 12-speed components.

I’m not sure when 11-speed Di2 production will cease, but even when it does, don’t worry. Even now you can still find 6870 Ultegra derailleurs and shift levers, and that was released in 2013.

crank arm power meters

If your parts have failed, by the way, be sure to contact Di2 GP on Instagram. He is based in the UK and frequently rebuilds and repairs Di2 derailleurs.

Crank-based power meters and 12-speed Di2

More and more people buy power meters nowadays. They’re not as expensive as they used to be and crank-arm power meters are especially common.

So if you own one of these you’ll probably be wondering whether or not you can install this on a 12-speed Ultegra or DURA-ACE bike.

Officially, no.

I asked Shimano about this specifically and this is the response I got:

The old and new spindles have the same construction and they might look like they fit but the Q-factor is slightly different (the new crankset has a wider Q-factor) and cosmetically the colour is different. It’s not been designed or tested to work together and we can’t say how that might affect riding.

Reading between the lines though, I believe you can get away with it.

The good news here is that the spindles have the same construction and spline patterns, just like all other HollowTech II cranks. It is true that the Q-factor is different, but the difference is only 2mm (146mm vs 148mm).

Considering that the total Q-factor difference is 2mm, the difference on the non-drive-side would only be 1mm. In the case of play on the crankset, companies like Wheels Mfg make Shimano compatible crank spindle spacers in both 0.5mm and 1mm widths.

One thing to keep in mind though - when using an 11-speed crankset with 12-speed front derailleurs, there is only a tiny gap between the front derailleur plate and the crank arm. See the image below.

There is only a tiny gap between the front derailleur and 11-speed crank arm (left), while the gap is larger for the 12-speed crankset (right)

Personally, I’d rather sell the old power meter and buy an officially compatible version to match the new cranksets. As I mentioned before, they’re not all that expensive, and bike aesthetics are worth something too.

12-speed Di2 wheels

Wheels… what about those?

Shimano’s new 12-speed cassettes come with a new spline fitting pattern, which is in fact backward-compatible with 11-speed freehub bodies.

12 speed shimano cassette

Of course, the new DURA-ACE wheels come with a freehub body that only accepts the new 12-speed cassettes, but your existing 11-speed wheels will accept 12-speed Shimano cassettes no problem! Also, the Ultegra wheels have an 11-speed freehub, so they'll take both 12-speed and 11-speed cassettes.

Junction A? Can you use your existing display with 12-speed Di2?

While MTB-style displays like the SC-MT800 and SC-M9051 are rare on road bikes, some people prefer those over traditional A Junctions.

wireless unit versions

They display the current gear, synchronized shift mode, battery status, and they emit a warning beep when you reach either end of the cassette. Also, they have built-in Bluetooth/ANT functionality.

If you're looking to transfer the display to a new 12-speed Di2 bike, don't bother. The system won't work.

The main reasons for this are:

  • You can only have one Junction A installed. The new 12-speed rear derailleur is essentially a Junction A, so you can't add another one (the display).
  • A maximum of 1 Bluetooth/ANT master device is allowed in a Di2 system. The rear derailleur has Bluetooth/ANT connectivity built-in (to talk to the shift levers).
  • The displays' firmware was not updated to make them work with the new Di2 groupsets

It's not all bad though. Sure, you lose the display - but the Bluetooth/ANT functionality has moved to the rear derailleur. This means that you can set up your bike computer to display the current gear, battery status, and selected synchronized shift mode. You do miss out on the beep, but in my opinion, that is of more use on mountain bikes than it is on the road.

About that upgrade path

Unfortunately for those of you wanting to upgrade to 12-speed Di2 for little money, it doesn’t work that way this time around.

You can use 11-speed Shimano cranksets with 12-speed Di2 bikes, but be aware that the gap between the crank arm and the front derailleur is relatively small when using an older crankset. Other than that, 11-speed cranksets shift just fine - I have ridden my bike like that for two months.

There is only a tiny gap between the front derailleur and 11-speed crank arm (left), while the gap is larger for the 12-speed crankset (right)

There have been reports of other people also successfully using the 12-speed chain on 11-speed cranksets, so in theory, you could keep your current crankset and upgrade everything else. If you’re spending money on a new Di2 groupset anyway though, you might as well go all the way and upgrade the crankset too.

That should answer all your 12-speed vs 11-speed compatibility questions. If it doesn’t, just leave a comment below or send me a message.

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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