FlashBazbo

I've ridden Di2 for as long as there has been Di2. (What is it? 8 years? More?) And, for as long as there has been Di2, I've been in the habit of intentionally cross-chaining at the bottom of steep climbs in order to maximize the amount of drive I get at the base, while already being on the small ring for the climb. That has worked really well. No noise. No problems. All the way through 6870.


This weekend, I switched from 6870 GS to 8050 GS . . . and the bike won't cross chain into the small chainring / small sprocket combination anymore. In fact, it won't give me either of the two smallest sprockets while on the small chainring. If I'm on 11 when I shift from large to small ring, the Di2 automatically shifts two sprockets over (in standard shift programming).


I checked the e-Tube website and it doesn't talk about it, but all the charts now show the two smallest sprockets blocked off when the bike is on the small chainring.


When did THIS happen? There doesn't seem to be a compelling reason for it. (It worked fine last Friday!) Is there a way to program around the block? The derailleurs can handle it. I want my cross-chaining back!

TimothyH

What happens when you unplug the 8050 and plug the 6870 back into the system? Does it still automatically shift the rear when you move the front or does it only happen with the 8050?

If it is on purpose then shame on Shimano for not telling anyone that they are only getting 20 gear ratios.

I was >this< close to buying the 8050 GS derailleur the other day and so I'm super interested. I tried semi-sychronized and can't stand automatic shifting at all.


-Tim-

FlashBazbo

I don't know. But the other relevant change is that there was a firmware update near the end of the year. I suspect my LBS updated the firmware when they changed the derailleur.


I'm changing out my crankset tomorrow night and I plan to check the firmware update history and settings when I do that. Maybe that will tell me more.

robbyville

I haven’t set mine up yet but I believe that if you do not use synchronized shifting that this will no longer be an issue... put it on manual and see whatbhappens

FlashBazbo

It has never been on anything except manual "standard" shifting. No synchro for me.

ReneV

It sounds like semi-synchro: the other of the 2 synchro-shift options. I don't have the right battery for it myself but there's supposed to be jct-A button presses to both see and change the synchro option: no>full>semi>no.

FlashBazbo

You don't really have any personal experience with this, do you?


It's not at all semi-synchro. Look, I've been riding bikes for decades and riding Di2 for 8 years. I think I recognize manual shifting when I do it. The two lights flash exactly one time after the green light shows for battery status. (If you don't know what that means, google it.) The front shifts only when I shift front and the rear shifts only when I shift rear -- except to prevent the small chainring cross-chaining when the chain is already on the 11T or 12T rear. Any other front shift elicits exactly zero movement from the rear derailleur. It's manual.


Just so you'll know . . . if it were semi-synchro, the shifts would operate in OPPOSITE directions. Semi-synchro is set up to minimize the jump in gearing when you go to the little ring. When you go to the big ring, the rd shifts a couple cogs bigger. When you go to the little ring, the rd shifts a couple cogs smaller. (If you don't believe it, google it.) This anti-cross chaining shift is in the SAME direction as the shift to the small ring. It exacerbates the jump in gearing which is why I don't like it.

ReneV

What part of my earlier statement to this effect is unclear to you?

I seem to somehow have stepped on your toes. My apologies.

79pmooney

Does this bar you from the big-big combo? I'm not a Di2 guy so I have no interest here, but when I raced, I had no qualms about using either big-big or small-small. I never used them for long, but if it was a long climb with quick dip or fast stretch, small-small and I pulled off one of my better sprints on a course that I was over-geared for by going big-big (54-17; classic corncob) on the final corner so I could make an easy and dead silent shift and take everyone by surprise. Worked.

To have the manufacturer of racing gear decide that my tactic shouldn't be done? Huh?

Ben

Rogerogeroge

This is a built in spec for little ring/two smallest cogs. Big/Big is allowed. There’s supposed to be a way to override this in the settings.

FlashBazbo

I'm sorry about the cranky response. I thought you were the same guy who immediately before you said pretty much the same thing you said.

FlashBazbo

Big/Big is not a problem. It still works.


When I first noticed I couldn't shift the little ring to the little cogs, I thought the LBS must have messed up my rd stop when they installed it. Apparently not. Big/Little works fine.

TimothyH

@FlashBazbo, the 8050 can be unplugged very easily and old derailleur plugged in. The old derailleur doesn't have to be bolted to the bike. It can be done while the bike is leaning against the wall.

Just put it in the 11 rear sprocket and large ring up front and then unplug the new and plug in the old. Let the old derailleur dangle from the cable and actuate the shifter to shift the front to the small ring. See if the rear moves or not. If not then it is new behavior with the 8050.

Other than that, how do you like the 8050? Do you think it will help with chain slap and dropping the chain on rough surfaces? That's my hope.


-Tim-

FlashBazbo

I hope you're right -- and I hope it's obvious in the e-Tube software. Cross chaining was never a functional problem with this setup. I'm not sure why they want to restrict it.


In fact, the only problem I've ever had with Di2 was with first generation (2009) shifting the front derailleur to the small ring when pushing hard on a steep climb. In that circumstance, the shift worked, but it was sometimes powerful enough to bend chain plates. For that reason, I would like to avoid shifting the front in the middle of a steep climb, if possible.

robbyville

Bummer, sorry. Looking forward to hearing any remedy as I will be hanging my 9150 on a new frame once it comes in.

good luck!

FlashBazbo

[QUOTE=TimothyH;20100333
Other than that, how do you like the 8050? Do you think it will help with chain slap and dropping the chain on rough surfaces? That's my hope.


-Tim-[/QUOTE]



I've never had a problem with chain slap or dropping the chain on rough surfaces. In fact, I've done a LOT of rough gravel racing on 6870, including the Dirty Kanza 200, and never had a single issue. But I'm pretty meticulous about chain length / spec because I don't want to have those problems. And I have always used the GS version of the rd for gravel racing. I don't know if that has anything to do with my experiences being different.


Other than the cross-chaining thing, I don't see a huge difference with 8050. I'm using Dura Ace 9170 levers and brakes, and I like those a lot -- but I don't know how different they might be from 8070. As you might expect, they are nicer than the 6870 pieces. (Probably not worth the price difference. I didn't have to pay the upcharge.) But I very much like the current setup. Hopefully, I'm one e-Tube session away from complete happiness.

Steve B.

I recall reading somewhere that you need to set Gear Position Control to Do Not Set, in yhe configuration software. On the Di2 XTR manual it states “prevents shifting into gears that would lower the chain tension”, which makes sense given derailer position in that combo

Marcus_Ti

I have a Di2 8050 GS RD coming tomorrow and can look into this.

FlashBazbo

Thanks, Steve. I will look for that setting in e-Tube. That explanation makes perfect sense.

Rogerogeroge

That’s it. Gear control should be set to ‘off’

FlashBazbo

Houston, we still have a problem. I’ve got e-Tube version 3.3.2 hooked up and it’s not offering a way to change from “Set” to “Do not set” on the Gear Position Control. It says “Set” but there’s no apparent way to change it. Help!

Rogerogeroge

Are you set up for synchro?


If not, step 1 - update firmware.

FlashBazbo

Q1 - Yes, this is 2018 Di2.


Q2 - e-Tube 3.3.2 is the newest e-Tube and all firmware on the bike was already updated.



So . . . step 2? Do you know how to change the GPC to "Do not set" in this latest version?

FlashBazbo

One thing occurs to me. Since all the current road Di2 offerings are now available with cassettes sporting a couple more teeth (was 32 max, now 34; was 28 max, now 30), maybe Shimano is a little insecure about the slightly longer chains running around a small chainring and an 11T cog. It's not about cross-chaining at all. Just about chain length.


It's a theory.


And, for what it's worth . . . I have test ridden a 6870 with 50/34 front/11-34 rear and it worked fine. Absolutely seamless.

Fiery

If I remember correctly from what I read on another forum (can't find the thread now), this protection is active when the system is set up for a compact chainring combination. If you set it up for 53/39, it should work fine even if you are actually running a compact, while allowing you to shift into small-small. Does this make any sense to you? I don't have any personal experience with setting up Di2 so I may have misunderstood what the deal was.

Your theory about chain tension does seem correct, since it is exactly what they to for MTB Di2: https://productinfo.shimano.com/#/spe...r%20Derailleur (quote: The DI2 system limits cross chain to prevent a chain from getting loose.).