chojn1

For those who got it to work:
Is synchro shifting that much better than manual shifting?
Is the improvement worth the time and cost for the upgrade?
Thanks

akexpress 

this is the way I do all of our Di2 batteries on seat posts . Instead of double sided tape I just use electrical tape to wrap on each one of a slightly shorter foam piece then the video shows which makes it slightly tapered on each end to help start it into the seat post. Never had on vibrate out and even if it did it just sits in the seat tube still all wrapped up.

twocicle

Nothing special needed.

Simply using a wrap or so of old handlebar tape is needed around the ends of the battery. Make the lower wrap end around an inch from the lower part of the battery, then insert the battery leaving that unwrapped inch sticking out of the seatpost so that you can pull it out later if you wanted to.

That's it.

twocicle

That statement is really NOT CORRECT. Thumping a spec bible is not the same as IRL.

Plenty of people including myself have run 18T chainring gaps with both Di2 and mechanical double 10spd and 11spd without issue, and it shifted great when setup with a decent chainline.

Shimano's derailleur are known to be conservative, especially the 16t spec for the double FD.

oldacura

I've studied the shift maps some more & now I think that I better understand them. For Full Synchro is it possible (or advisable) to jump the rear derailleur 3 cogs when the front moves from low to high (or the reverse)? In one of the illustrations it appears that there are 14 possible gear ratios. Might jumping 3 cogs instead of 2 give one more ratios?

FrankScott

Has anyone got the Syncro shift to work with the RD-6870GS mid cage Ultegra DI2. I have all the bits and the programed the system for syncro but does not work.

Marcus_Ti

Do you have the new battery, and do you have firmware 3.0.0+?

FrankScott

New Battery - Yes
Updated Firmware - Yes

Marcus_Ti

I believe with the EW90 junction boxes you have to double-click the button on the junction to turn on synchro.


Allegedly there are some gear restrictions on it working....certain chainring setups are presently designed to throw an error on ETube.

FrankScott

That did it, Thank you Thank you.

twocicle

It is not a matter of adhoc mapping guesses, but reviewing your ratios and best progressions first (go to the HTML5 Gear Calculator), then mapping those shift points in the e-tube software.

oldacura

I did figure out the ratios for each combination and made a similar map. However, it appears that in full synchro, they jump only 2 rear cogs (going up or going down). I was just wondering if a 3 cog jump was ill-advised if it produced the smallest incremental change.

twocicle

I have run the Di2 multi-shift mode (hold shifter button for duration of cog shifts) set to the max allowed (3 cogs) from the start of when we first began using Di2. That worked great. Moving to synchro shifting with XTR derailleurs, again those will do a multi-shift of 3 cogs just fine if that is what I had mapped. You should just give it a try and see if you find the speed of the multi-shift suits your riding style. You can tune multi-shift speed in the etube software... from slow to very fast. I have never found the need to change the default speed.

IMO, if you have chosen your gearing (rings + cassette) well for your typical rides, shifting between chainrings is not a constant thing. I like to have my synchro chainring shift points at the extremity of what the crosschaining allows, and then map the rear to the next best ratio cog. Doing the mapping in this fashion allows for maximum use in the current chainring and conversely minimizes needing to shift between rings (one of the highest drivetrain stress loads, especially on a tandem). How many cogs synchro allows you to use for a given chainring position depends on how many rings you have. For example, with our current triple chainring setup when in the granny, synchro eliminates the ability to use the smallest 3 cogs. Whereas with a double chainring setup and the inner ring, you can use all but the outermost (1) cog.

shlammed

I believe @oldacura was mentioning that when switching chainrings he would like to use more than 2 tooth cassette gear change. In playing with e-tube project last night I had the same observations. 2 teeth is good for an approved setup, but when using non-approved gear combos it might not be enough.

oldacura

OK - makes sense. We'll be 2x11. If I set it up correctly, we'll have several overlapping ratios and we can stay on one ring of the other through a range before shifting the front. The rear shifts smoothly. The front is more "dramatic" as the jump is so big.

twocicle

I haven't tried this yet, but I wonder if the multi-shift setting governs the "full-synchro" maximum cog shift too? Might be something to test. I don't have all the components needed for road Di2 synchro to test full-synchro.

mtseymour

Do you prefer manual, full synchro, or semi-synchro mode? We'll have more time to test various configurations this weekend but our default will probably be full synchro.

oldacura

I notice that on the display there is "M" (manual), S1 & S2. It looks like one toggles between the 3 by pushing the mode button (twice). I'm guessing that S1 & S2 could be either full synchro or semi-syncho. I suppose one could select a different mode & different shift maps for each or set them up identically. My expectation is that once I dial in full synchro and get used to it, I will likely never select either of the others.

twocicle

Ok, I finally gave a damn... enough to go read up on the new Di2 User Manuals for mtb and road. Figured I better do this before connecting up the newer eTube version to my 785/XTR-mtb fd/rd mashup.

The Road - "Synchronized shift" as it is called in the Road User Manual (I believe what you are calling "full synchro") is exactly the same as what we have with the mtb synchro functionality (simply called "Shift Mode" in the mtb user manual). The shift mapping limitations are the same, as described in the user manuals. Your range of cogs that you can map to is dictated by the ratio differences eTube thinks you have, so the chainring & cassette selection will dictate those maximum jumps.

FWIW, last time I mapped our Di2 with the mtb synchro setup, we only had 1 cassette to choose from (11-40) and no chainrings because as far as XTR was concerned there is only 1 triple XTR set (40-30-22T). Luckily, with our 48-36-26 and typical 11-28 or 11-32 cassette I did not hit any critical shift map points that could not be done.

The Road - "Semi - synchronized shift" as it is called in the Road User Manual, is different than what we already get with the mtb synchro functionality noted above. Where our manual FD shifts will only cause the RD to move if you are tripping the crosschain maximums allowed, the Road - Semi synchro will try to figure out the best next gear ratio based on what gear ratio you are changing from, and this RD action can occur when in any cog position, not just if you hit a crosschain maximum. At least that is my understanding from reading the manuals.

Without playing with the Semi synchro, I really can't get a feel for how that would work out on the road. I am very happy with the mtb Syncro shift (what you call "full-synchro" on the road setup), so all things considered, probably not worth the expense of updating my BTR2 battery and display unit from a M9050 to M9051 or XT equiv.

oldacura

twocycle - thanks for the link. I printed & will read these manuals when I get a chance. I played with the software some more last night. I accepted the widest default gear ranges listed (52-36 and 11-28). When I tried to edit the shift mode settings, I could move the shift points up & down except for the 52t x 25t. It would not allow me to move this down to 52t x 23t. Don't know why. I'd like to avoid the bib x big and big x 2nd big but I can't. Any explanation? Also, when in Synchronized Shift and shifting on a bike stand I notice that the most "dramatic" shift (noisy = bad) is when the front moves from small to big and the rear does a corresponding shift 2 cogs bigger. Not sure I can avoid this without defeating the purpose of synchro shift.

mtseymour

When using full synchro in the big ring (52T or 50T), the e-Tube software won't drop to the small ring (eg. 34T) until the rear derailleur reaches the 10th cog (with 11 being the largest). This quirk in the firmware has already been discussed in posts #25, #37, & #38. Shimano should be able to remove this restriction with the next firmware upgrade. In the meantime, just downshift from big to small ring if you don't like this gear combo. You can still control the front derailleur when in full synchro mode.

I think that your "dramatic" shift is due to using chainrings with a 18T gap (52-34). Your rings may do a synchro shift, but not as smoothly or quietly as the specified 52-36 or 50-34 rings. This is one reason why Shimano, Sram, FSA, and Campy cranks only offer rings with 16T gaps.

oldacura

Ok - I read posts 25, 37 & 38 and I see that this was a choice by Shimano. I now also understand that my "dramatic" small ring - big ring shift is because of my 18t jump. I'd like to try it on the road this weekend but we're supposed to get a lot of rain.

mtseymour

I've had a few rides and tried to find glitches with full and semi synchro shifting.

In full synchro mode, the front shift (eg 34T to 50T), is very fast, reliable, and seamless. It's significantly better than regular Di2 because the gear jump is adjustable, and there's no need to slow down or ease up. In fact, it's better to maintain the same cadence or power output. This is possible because Di2 will move the rear derailleur to one easier gear (or 2) just slightly before the front derailleur moves to the big ring. This is something that's very difficult to do manually.

As discussed in prior posts, the e-Tube firmware prevents a downshift (eg. 50T to 34T) until the rear is at the 10th cog (w 11th being he largest). I don't like the cross-chain but the full synchro works fine. It would work even better if the next firmware upgrade will allow the cross-over to happen sooner.

It's worth noting that it's possible to manually change the front derailleur in full synchro mode. So I just drop into the small ring whenever I like.

The semi synchro mode is for riders who always want to control the front shifts. It works as advertised but I don't expect to use it much. The full synchro works so well the semi synchro mode is almost redundant.

This may be obvious, but Di2 works better with forged rings with ramps and pins. My first choice are the Ultegra/Dura Ace rings but their bolt pattern is incompatible with most tandem cranks. The 5-bolt SRAM Red and Praxis rings are good substitutes.

oldacura

We tried full synchro for the first time this weekend on a 30 mile ride. I think this does a good job of compensating for a limitation that I have with Di2: we want a wide range but can get there only with 2 rings. So the jump from the big ring (52) to the small (34) is big. Having the software compensate for this jump by simultaneously moving the rear derailleur 2 or 3 cogs in the opposite direction really helps. However, it seems like the front shift happens pretty quickly and the compensating rear move is delayed by a second or so. It would be nice if the rear moved more quickly. Maybe I can adjust the shift speed (particularly the rear) from normal to faster. Also, I found that we stayed either on the big or small ring for a while and shifting the front was infrequent. Anyway, I am quite happy with this upgrade and will continue to tweak it to our tastes going forward.

mtseymour

Synchro shifiting is significantly better if you're riding in heavy traffic, a big group, or rolling terrain. It's just one less thing to worry about. There's no need to ask your stoker about gear combinations to avoid cross chain, or to prepare for an abrupt climb or a surge in the paceline.

The upgrade was easy to do. The cost of is zero if you're switching from mechanical drivetrain to Di2 because the new DN110 battery is standard on new groups.

If you already have Di2, you can get synchro shifting by spending about $70 (new battery with current Junction A) by selling your current SM-BTR2 battery. I was able to sell a pair of used SM-BTR2 batteries easily on eBay.

The new SC-MT800 display is really handy for tandems. This will raise your incremental cost to around $100-120 (battery + display) if you sell the existing Junction A. I also did this on eBay.

If you already have the M9050 display, it works fine with the DN110 battery (but without Bluetooth and ANT+).

So synchro shifting is an inexpensive upgrade.