mtseymour

The recently announced Shimano Dura Ace group (R9100 & R9150) offers synchronized shifting for tandems with road Di2 drivetrains.

By upgrading the battery and junction box, Ultegra 6870 Di2 users can get synchronized shifting. Apparently, there are two shift modes. The full synchronized mode means that you can control both derailleurs using a single shifter. Pressing the downshift or upshift button will make the front and rear derailleurs to move you into the next available gear ratio. This feature is targeted for time triallists and triathletes. Launch date is around Nov but pricing has not been announced.

Tandem riders will probably prefer the “Semi Synchronized” shift mode. This mode repositions the rear derailleur whenever you shift the front derailleur, moving it to the next appropriate gear. This will reduce the gear jump when using 50-34 or 52-36 ring.

The other news is the availability of Dura Ace hydraulic disc brakes. The ST9170 hydraulic shifters should be slimmer and lighter than the current ST785 shifters (360g vs 510g). I assume that the new shifters will be compatible with current Shimano XT or R785 brake calipers. Unfortunately, the new Dura Ace rotors are too small at 160mm, and the disc calipers use a flat mount that may not be compatible with most tandem frames.

oldacura

Wow - This could make me an early adopter. We've got Ultegra Di2 (not sure of the model). I also installed the XTR display.

I would prefer that they offer a triple front but it sounds like this is not to be. A synchronized (or Semi) might smooth the huge gear jump when shifting a wide range front double.

Please keep us informed.

Thanks.

twocicle

Good to post some links...

Shimano Introduces New DURA-ACE R9100 Road Components, Integrated Technologies
Shimano Dura-Ace R9100 and R9150 Di2 electronic: weight, price, pictures and more - BikeRadar USA
https://cyclingtips.com/news/shimano-...-weight-price/

^^^I haven't used any flat mount calipers yet. Can typical IS or Post mount adapters be used?

Nice to see the weight of the new Di2 DA disc shifters is actually 5g less than the DA mechanical, and slim looking instead of the current bulbous Ultegra dolphin head.

DrMarkR

We have this on our XTR Di2 setup on our Ventana ECDM. 2x11. Works very well, and I would think it would be even better received on the pavement?

I had assumed installing the synchro junction box was all that was needed with the road Di2 group?

akexpress 

Hopefully it will just be a firmware update and e-tube software new version that will allow the road Ultegra Di2 to allow this and maybe before Dura Ace is released.

mtseymour

Synchronized shifting will require a new battery that has more capacity and a new junction that can handle the additional programming. You'll need a new battery because Synchro Shift uses more power than manual Di2 shifting. Synchro shifting relies more on the front derailleur, which uses more force to execute each shift. The good news is that the new Junction A comes in many forms, including placement inside the downtube and in the handlebar. The junctions can now reside inside the frame because the new battery will be charged via a magnetic adapter without access through a cover or hatch.

Although Shimano didn't mention it, it would be really nice if road stems and bar will be pre-drilled for Di2 wires. With the XTR Di2, it's possible to run the shifter wires through the handlebar and into the stem. This internal wiring provides a sleeker cockpit and makes it harder to snag the wires or water getting into the frame.

If Dura Ace Di2 follows XTR Di2, the payoff is customized shifting patterns for each tandem team. With the XTR Di2, it's possible to toggle between the S1 and S2 shift modes. Using the Shimano E-Tube software on a PC laptop, S1 can be setup to drop to the smaller chainring (eg. 50T to 34T) earlier, weighting the gearing range towards the lower end, and maintaining a straighter chain line overall.

Racers and aggressive tandem teams can use S2 as a ‘race’ setup. With this setup, the chain would remain in the big ring (eg. 50T or 52T) until you’ve downshifted to the bigger cogs (eg. 25T or 28T), and only then would the front derailleur drop to the inner 34T or 36T ring. When upshifting, it possible to configure the shift patterns to be more aggressive, with a larger jump in ratios between gears. XTR Di2 will also give a audible beep when making a front shift to make the process more predictable.

oldacura

mtseymour - Sounds like you have your ear to the rail. Let us know when & where the new battery & junction box are available.

twocicle

My understanding is that the current XTR Di2 Display/junction box + XTR derailleurs + Road shifters provides the synchro ability. I have not read anywhere of issues with the current internal e-tube battery, even with the mtn synchro mode enabled. So if only wanting to upgrade to the new DA shifters, I can't see needing to get the new DA battery as well.

The battery is only needed if using the DA derailleurs (2x11) with synchro mode because those are slimmed down and don't have the logic chip in them which is being added to the internal battery instead.

FWIW, I'll go on record right now to say that I think synchro for road is a total bag of stinking hype. For sure it can be of value trail riding, but for road riding... no thanks.

mtseymour

Ultegra Di2 shifters may work with XTR Di2 derailleur, but they can't provide synchronized shifting. There's a thread at Fairwheel Bikes that explains the various reasons why it's not feasible (bigger gear jump, double-click function, etc):

Shimano Di2 Synchro Shift for road bikes? - Fairwheel Bikes Blog

For tandem teams who are happy with mechanical shifting, synchronized shifting is not a compelling reason to upgrade to Di2. However, it's a reasonably affordable upgrade ($200-300 for battery and junction) for those who already own 11sp Di2 or plan to switch in the near future. We'll have plenty of time to weigh the options while waiting for the spring 2017 launch date. I don't see any downside for Di2 to coordinate the front and rear derailleurs for fast & smooth gear changes.

Dean V

Personally I don't see any value in the idea. I especially wouldn't like the fully synchronised option on a tandem as I like to know when the front mech is going to shift.

chojn1

As far as the "semi synchronized" shifting, how hard is it to remember to double tap the right hand buttons every time you tap the left?

twocicle

The Fairwheels article is old and wrong because they tried it with the road junction box A. We discussed this in TurboTandem (Andy's) "Gravel Grinder" thread. Andy has Ultegra road Di2 shifters + XTR Di2 derailleur and this DOES SYNCHRO shift. The key is that you also MUST HAVE THE XTR DI2 DISPLAY AND NOT THE EW90 JUNCTION BOX. I'm shouting this, because it has been stated multiple times here in the tandem forum. Andy has proven it works.

Synchro on a road tandem does not seem feasible as we generate a lot more pressure on the drivetrain and need more care in coordinating our shifting. Regardless of synchro or manual, it is still best to back off that pressure especially for front shifts. If you forget that synchro is going to shift the front (and the stoker won't hear a warning beep from the display unit) then you are asking for trouble.

mtseymour

I started this thread is about road tandems. Turbotandem built a 29er Paketa for gravel rides and backcountry racing. He used 10sp Ultegra 6770 shifters with XTR Di2 front and rear derailleurs for a 22-34-44 crankset and 10-42 11sp cassette. He achieved his goal of building a gravel tandem with road shifters, rather than using the superior XTR shifters on flat bars.

Not surprisingly, his Paketa doesn't perform like a road tandem. Since the XTR Di2 front derailleur is only rated for 40T and 74mm mtn bottom brackets, Andy's says that his hybrid setup "shifts fine but oh so close to not working". I would expect the shifting to be more problematic when using 50-34 or 52-36 cranksets. I realize that Santana has modified a XTR Di2 derailleur to handle a 52-42-30 crankset, but I'm doubtful that it can match the shifting from a Ultegra front derailleur on a road frame (w 68mm BB).

In addition to sub-standard shifting, these modified Di2 setups lack firmware upgrades and dealer support. For road teams who are happy with 2x11, upgrading to synchro shifting is simple and relatively affordable way to get superior shifting, updates and dealer support.

I don't understand your comment about feasibility. First, you say that "Andy has proven it works", and then you say that "Synchro on a road tandem does not seem feasible". These seem like contradictory statements.

After using Ultegra 6870 Di2 on our Calfee and Dura Ace 9070 Di2 on my Giant TCR, I haven't experience the need to reduce pedaling pressure for front shifts. Both Di2 setups have been completely reliable. I haven't read a professional review that suggests that Di2 requires riders to ease off when making front shifts, or that elite racers can over-stress the front derailleur when attacking or sprinting. Racers like Mark Cavendish can generate over 1,000 watt during sprints. How many tandem teams can come close to that?

On the contrary, I expect synchro shifting to reduce stress on the drivetrain and the stoker. For a downshift from 50 to 34T, the rear derailleur will move to a smaller cog, making it less likely for the stoker to spin out. Seem more comfortable for the stoker. For an upshift, Di2 may shift to the 50T or a smaller cog. However, it will choose an appropriate gear to avoid a sudden power surge (or much slower cadence). Again, this should make the stoker happy without the need to yell out a warning.

oldacura

We have quite a bit of experience as a tandem team. Most of this is with 3x8 Ultegra setup shifted by bar-end shifters. I had very little complaint about the range of gearing or the reliability of shifting.

My single road bike is Dura Ace STI 2x10. The range is OK but the quality of shifting is not as crisp as the bar end shifters.

Our new tandem is Ultegra Di2 2x11. The range is OK and I'm getting used to the shifting. I think it is better than my single STI but the shift steps are too big to make shifting a no-brainer.

I would like Di2 with 3x chainrings but that sounds like it is not to be for the road. I think adding synchro-shift may make the shifting more of a no-brainer. I think it would be nice to be able to tell the system that I want to shift either up or down to the next ratio and have it figure out whether to shift the rear, the front or both.

Many here have touted that with Di2 one can shift under load. While this is possible, it is not elegant and I think it will put major stresses on the derailleurs, chain and cogs.

Racers put big loads on their drivetrains but someone else pays for their bike and does their maintenance. They rarely use a bike more than one season. We bought our bike, I do most of the maintenance and want to keep the bike for a long time.

Will Di2 shift under load? Yes. Is this a good idea? I don't think so. Calling out "shift" to my stoker so she can ease up for a fraction of a second works really well (and the derailleurs like it too).

waynesulak

I believe that cadence should be included in any discussion about shifting under load. For us 90+ cadence means smooth quite 3x10 mechanical shifting. As cadence drops below that level shifting under full power gets rougher and louder. Like a lot of things on the tandem, team style, size and power makes it hard to compare between teams.

DrMarkR

I chuckle at everyone stating they think synchro "sucks" for road tandem, even though (unless I'm mistaken), not one person saying this has even ridden an XTR synchro bike.

Reminds me of the same crew of folks dissing Di2 when it first came out.....


Carry on.

akexpress 

I am hoping the new software update will allow mixing road and mtn derailleurs as that will open lots of possibilities. At least we are starting to have more choices to do what suits you. Choices are always good!!!!

Dean V

It is a different situation. The people dissing Di2 originally didn't know what it was like so it was an uninformed opinion.
Now that we have it we know exactly what it shifts like and even though it is very good a number of us would still prefer to have control over front shifting.

chojn1

Shimano went out of their way to break compatibility between the two ultegra groups. I doubt very much that they will ever reverse course and offer more choices.

oldacura

I would like it if they created software to permit one to select synchroshift, semi-synchro or independent and allow the rider to decide choose which mode they prefer.

chojn1

Shimano is pretty good about giving you those choices. The question is if the synchro shift is worth the extra expense of the upgrade for limited benefit. No use paying extra for something you might never use.

oldacura

I guess it depends what hardware changes are necessary. We already have the XTR display. It sounds like we may have to buy a new battery. If the new battery is not required, this could be just a software upgrade.

I never thought that I would be using the term "software upgrade" with regard to my bike.

oldacura

I talked to Rob at Calfee today. He says that Shimano will be releasing a software update for eTube Project in late August. This is to coincide with a rollout of new Dura Ace Di2.

It sounds like synchroshift will cause the FD to shift more often causing it to deplete the battery faster. I don't know if a new, larger battery will be required or just recommended. Also, we have an XTR display instead of a "junction A box". Again, I don't know if this will be required or just suggested.

If all goes well, one could try one or the other versions of synchroshift & see how they like it or just revert to "manual".

DrMarkR

What do you mean by semi-synchro??

DrMarkR

With the charging port on the synchro unit, doing so is extremely simple. And there's an icon on the display that shows level, as you likely know. Finally, battery life on our bikes (DA Di2, Ultegra Di2, and XTR) is all amazingly good. The FD is apparently most of the battery drain, as one would expect.

I did buy the eTube interface, as the local shops wanted $25/hr to let me use their's....no thanks. Nice to use for custom programming on the synchro.