M4tt3

Hi, my Di2 is not shifting accurately to two of my gears, 3rd and 4 smallest cog on the casette. All other gears are smooth but with these two I have to go two up one down. I obviously tried indexing and I think that if I could index it once or twice more up, it could be fine but it is at its limit. I am thinking of adding a washer to move the derailleur slightly towards the wheel to see if I can index it then. The bike was previously crashed on the side of the derailleur so I am not sure if that's the problem. I already changed the hanger and had it service but the mechanic couldn't identify the problem. The chain is soon due for changing but the casette should still be ok. Any suggestions what may be the issue?

Iride01 

When you say you indexed it, how do you mean indexed? Did you get into eTube project or use the buttons on the junction box to set the micro-adjust positions for each cog? Regardless if you aren't an expert with Di2 adjusting then I'd recommend you go back and ensure all the installation and setup was done by the Shimano manuals. Here's a link to where you can find some useful Di2 info and also links to the appropriate Shimano manuals.....

https://bettershifting.com/

If your bike was previously crashed on that side, then some sort of damage to the DR or it's hanger, which you already said you changed, would be the most expected thing IMO.

Barry2 

New hangers are not always straight when mounted to your frame.
Have the hanger alignment (re)checked.

Barry

Steve B.

Sounds like you have a bent derailer hanger resulting from the crash

Koyote

I can't imagine how adding a washer could move the RD towards the wheel.

Barry's suggestion is likely spot-on. New derailleur hangars often need to be aligned upon installation.

Since your mechanic couldn't straighten it out, you probably need a new mechanic.

cxwrench

Huh? You can't do that...you can only adjust the derailleur's position the same way a barrel adjuster would. It's the same for every shift, you can't adjust each cog individually.

M4tt3

Thanks for all suggestions.

I will go back to my mechanic, who actually is very good IMO and also Shimano trained, to check the new hanger which I installed myself after he checked and realigned the old one as he couldn't figutout the problem, suggested to get a new one. I would post some pictures as it looks straight to me but the forum doesn't allow me to do that for being newbie.

With regards to indexing, I just used the junction box. I will have a look at the eTube project. Would that allow me to index it in any other way?

The washer I was thinking of if put between the hanger and frame would in my mind move the DR towards the wheel although it's a bit dodgy patch even if it works.

Do you this is it worth to change the casette although this is still good according to the chain wear indicator?

I want to explore all options before buying new DR.

​​​​

TerryDi2C

Nope!
It'll let you perform the same adjustments. However, it will tell you the current adjustment values.
RD-R8050/RD-R9150 have 16 steps in either direction: -16 <> + 16.

If it's maxed out, then I would definitely check the hanger, as well as making sure the derailleur is attached correctly. It's surprisingly easy to get wrong .

Sometimes - and I'm not saying this is your problem here, but it's good to know - frames (derailleur hangers) are slightly out of spec, and they require you to set the adjustment all the way to -16 or +16 in order to work. Generally that means shifting is off for the entire range though, not just one or two sprockets. In that case a washer can help.

In this case, with shifting off in those two gears, my first suspect would be the derailleur hanger, but also double check that the cassette is installed correctly, and that the wheel is in straight. You've probably done that already, but hey ;-)

Koyote

Yep, and yep, and yep again.

If one of the cassette spacers is not seated correctly, or they got mixed up, shifting will be 'off' on part of the cassette.

A mechanic will have the tool to easily check the derailleur hanger.

Last possibility is that the cassette needs replacement, but OP stated that he thinks that's not the issue. But on my bikes, when the shifting is off as described, it usually means that I need a new cassette.

M4tt3

So I checked the settings on eTube and it's max out on -16. I am taking the bike to the mechanic tomorrow to check the DR hanger.

Barry2 

Fingers crossed that all it needs is a hanger alignment..
Please do come back and let us know your findings.

All the best

Barry

BTW: I really "like" tools. After my bike toppled over the second time, I decided to purchase a Hanger alignment tool.
I thought I'd break it out once every year or two and save myself a trip to the store.
Turns out I've more friends than I thought, and most will trade IPA for an alignment.
Of the specialized tools I own, this one has seen the most use.

cxwrench

Every cassette I've seen lately has spacers that are all the same size excepting some Campy models. If the hanger is out of alignment (in the normal bent-in fashion) the shifting will generally be ok in the smaller cogs and get worse/noisier as you move to bigger cogs. I can't imagine one being bent such that the shifting is only bad in a couple of cogs. I'm thinking this is a worn out cassette.

Barry2 

OP didn't mention changing the hanger himself until post #7.
I wonder if other parts or pieces have been replaced following the original crash.
Like original old/worn cassette being mated with a nice shiny new chain.

Barry

Koyote

Probably. Any time one of my bikes starts shifting badly in just a few cogs, they are the cogs that I use most often and are worn.

Iride01 

I would have sworn you were wrong, because I thought I'd gone into eTube and done that. However I took time to go back in and looked.

I guess the screen where they allow you to shift to each cog and adjust the DR position confused me. I thought I was setting it for each cog. Now that I go back and look I see that when I change it for one cog it changes it for all cogs.

Hrummmph!

M4tt3

The change of the casette will be my next try

M4tt3

I should have the bike back this afternoon so will let you know if it's sorted or not.

rm -rf

This guy had an unusual Di2 shifting problem. Every gear was hard shifting, the indexing was all the way to one end, and he couldn't reach the biggest cog! It turned out that the hanger was too thick. He had it milled down and then it worked. (see the last few posts in this thread).
But I don't think it ever worked correctly from day one, from the factory. Strange that the bike company didn't test it?
His post 16 says: "after a firmware update is etube, my lbs said they performed some trim adjustment via stubs that is more precise or not available to perform via the shifters. These two things allowed them to trim enough to produce acceptable shifting." I've never heard of e-tube only adjustments, different from the junction box micro-adjustments.

Troubleshooting

Your shifting was working correctly in the past for all your gears?

Once it's finally in those bad gears, does it make noise from chain rub there?
Put it in the big ring, shift to larger cogs, then downshift to the bad cog. Does the chain rub? I use a dollar bill as a feeler to see if there's a slight gap between the chain and the next larger cog. Turn the crank a little and check a few more times. I also look at the chain while turning the crank very slowly on the bike stand, looking for tooth interference with the next smallest cog--the chain link gets pushed slightly then rebounds. This is quite unlikely if the inboard spacing is correct.

If your mechanic used the Park Tool hanger alignment tool, then the old hanger shouldn't be the problem. Did he have to use the tool to bend it a lot to get it back to alignment? If so, it's not a bad idea to put on a new one, for the small possibility of the old one cracking eventually.

I tipped over my bike this year. it was still shifting okay. So I checked the alignment when I needed a new chain -- and it was very slightly bent. l straightened it with the tool. Shifting seemed fine before or after.

Bad shifting in just in two gears. That's very odd.

I think that a new chain shifts slightly better--a little faster. But it doesn't cause bad shifts with an old chain. Off the bike, I can bend the old chain "sideways" much farther than the new chain, which has less flex there. So that could help with a bit better shifts on a new chain.

Worn cassette cogs
I was thinking about how this would affect shifting. The usual symptoms is a spontaneous gear change when sprinting or standing up. "popping" to a new gear or a loud noise. The chain rides up toward the tips of the badly worn gears.
Do you have the chain trying to jump to another cog at times?

Cassette spacers
On Shimano, all the spacers are the same thickness. A missing spacer wouldn't work at all--two cogs would be jammed together. I suppose the lockring could be loose? but the mechanic would have noticed, I hope.

My older bike had Campagnolo 10 speed, and one spacer was thinner than the others!

TerryDi2C

This doesn't really matter here, but just in case some future user reads this thread.. 12-speed Shimano road cassettes do use different spacers. They're not all the same thickness.

Barry2 

And they call that progress.

Sounds more like a cluster, looking for somewhere to happen.

Barry

Koyote

It's not terribly difficult to keep track of spacers and their locations...but granted, I'll bet Shimano could've designed the 12sp cassettes to NOT have the different spacers. But it might's raised the prices by fifty cents or something.

Barry2 

I have trouble just keeping the cogs in the correct order.

Spacers as well...... that means I can no longer clean my cassettes with IPA.

Barry

M4tt3

So just came back from the shop. The mechanic also sent me a report from eTube which shows an error on the line "can gears be shifted correctly" and therefore thiks that there is an internal problem with the DR and it will need replacing .

He confirmed that the new hanger is correctly installed and that the spacers are also in place and in correct order - mine is 11 speed.

I don't think that the thickness of the hanger is an issue as it was shifting poorly with the old one too. I bought the bike second hand and at the beginning I haven't noticed shifting problem and it appeared gradually.

The chain doesn't jump to another cogs and it's not even worn out to the point when it needs replacing.

I will have a closer look whether the chain is rubbing at the bad cogs as you suggested and maybe try to put a washer in between the frame and the hanger bu it seem that at the end I will really need new DR. ☹️

Barry2 

TerryDi2C
Terry,
Isn't that report just an e-tube checklist that is completed manually by the tech?
I don't believe that value is reported by the RD itself.

Can you confirm?

Barry

M4tt3

It looks like proper report. I will try to share it here.