One Di2 rear cassette cog out of sync - going crazy here

Triathlon Forum
1

Love my Di2. It’s not perfect though. Ten out of the eleven gears in back are near perfect and smooth.

That leaves one gear that lightly “chatters”. It doesn’t leave the gear or skip. There is no loss of power. It’s just irritating that 10 of the eleven are silent and this one is talking to me. It only chatters while under pressure on the road and I can’t replicate it on the bike stand.

The ONE gear seems to be the 4th or 5th from the smallest cog. On my 12-25, that would be either the 15 or 16 tooth chain.

I do adjust the rear derailleur in the adjustment mode from the 5th cog from the top and then micro adjusting per the manual and videos.

What am I doing wrong? I don’t think micro adjusting the one cog that is chattering can be done without throwing off the others or can it?

2

How’s ur B screw set? Can you get the pulleys a little closer?

3

How’s ur B screw set? Can you get the pulleys a little closer?

That - I have not done. Will get the bike on the stand and give it a try. Thanks.

4

How’s ur B screw set? Can you get the pulleys a little closer?

Made that adjustment. More tension seemed to draw the pulley closer to the largest cog in the cassette. Then I put the rear in the 5th cog from the top and made the electronic adjustment.

Tomorrow’s ride will be the test if it worked or if I did it right.

What rings true to your question is that the Di2 was set up for a 11-28 cassette for N GA riding. In FL, I switched to a 12-25 cassette without even thinking of pulley distance to cassette.

5

I betting Fishbum is correct about the b tension. I had a similar issue with my etap last year. The b tension fixed it and I was annoyed at myself for not thinking of it earlier!

6

Not trying to hijack, but I have a related question of my own. I have 11 speed Di2 on my new bike. I can’t shift into the smallest cog. only being able to access 20 of the 22 gears seems weird to me, but the shop says it can’t be changed. This seems a little ridiculous. ls the shop correct?

Thx

7

That’s not correct. You should find a new shop. Likely a simple adjustment, but could also be a bent derailleur hanger.

8

Is it possible they put a 10 speed derailleur on an 11 speed cassette? They say it can’t be changed and it is brand spanking new (now it is technically a few months old, but asked them to fix it a day after buying it).

9

When in the smallest chainring in the front, the R8050 Di2 rear derailleur will not shift into the smallest two cogs in the rear to prevent cross chaining and the chain rubbing on the inside of the large chainring. It comes set from Shimano like that and it cannot be changed. If you are in the small chainring and the third cog in and need a harder gear you will need to shift the front derailleur and then shift the rear to correspond. Remember that a 2x11 group has 22 gear but really only 14 unique gears because of overlap in the gear ratios.

10

Interested to hear how this went. I have a brand new cassette (12-27, 10 speed) and brand new chain on my Neo, and I have one gear in the middle, 5th up from the smallest, that clicks. The others are butter smooth. Funny thing is if I shift into and out of the nuisance gear a couple times, I can usually get it to shut up, but most of the time on the first shift into the gear it clicks. I can adjust the r/d tension to get rid of it, but it messes up the rest of the shifing. Annoying. Haven’t looked at B adjustment screw yet.

11

When in the smallest chainring in the front, the R8050 Di2 rear derailleur will not shift into the smallest two cogs in the rear to prevent cross chaining and the chain rubbing on the inside of the large chainring. It comes set from Shimano like that and it cannot be changed. If you are in the small chainring and the third cog in and need a harder gear you will need to shift the front derailleur and then shift the rear to correspond. Remember that a 2x11 group has 22 gear but really only 14 unique gears because of overlap in the gear ratios.

This is not correct. It is dependent on the chainring combination that you select in the ETube software. It can be overridden. I think it is the ‘gear control’ option if my memory serves. It’s been a long time since I set mine up. I am running 9150 derrailleurs with a 12-28 cassette and 53-39 chainrings and I can access all possible cog and chainring combinations.

Have a look around in the ETube software. You may not want to override it with certain cassette-chainring combinations as you might get too much slack in those two smallest cogs when on the small chainring, but the option is there to trick it if you really want to.

12

Interested to hear how this went. I have a brand new cassette (12-27, 10 speed) and brand new chain on my Neo, and I have one gear in the middle, 5th up from the smallest, that clicks. The others are butter smooth. Funny thing is if I shift into and out of the nuisance gear a couple times, I can usually get it to shut up, but most of the time on the first shift into the gear it clicks. I can adjust the r/d tension to get rid of it, but it messes up the rest of the shifing. Annoying. Haven’t looked at B adjustment screw yet.

Adjusting the B screw made a difference. Too much of a difference because I’m the type of the person to overdo “a fix” by giving it too many turns. Now some of the other shifts are a little off - although the clicking is gone.

Taking the screwdriver with me on the next ride because the clicking is not one of those things that happens on the bike stand. Hopefully, I will find that B screw sweet spot that meshes with the Di2 micro adjustments.

13

In every single case, unless the derailleur is twisted and no longer stays parallel as it moves, if you cannot tune all gears in, your hanger is crooked.
It is that simple, yet people deny this over and over again.
Pretty much every bike that comes in for service, the hanger is bent to some degree.
No they are not aligned if you bolt on a new one.
It may not be aligned if you change wheelsets and there is significant dropout wear.

But if you can tune in part of the cassette and not the rest, it is bent.
Don’t tell me it is not and it is some mystery thing that nobody else has had to deal with.
It’s bent, get it aligned, ride the frucking bike.

14

In every single case, unless the derailleur is twisted and no longer stays parallel as it moves, if you cannot tune all gears in, your hanger is crooked.
It is that simple, yet people deny this over and over again.
Pretty much every bike that comes in for service, the hanger is bent to some degree.
No they are not aligned if you bolt on a new one.
It may not be aligned if you change wheelsets and there is significant dropout wear.

But if you can tune in part of the cassette and not the rest, it is bent.
Don’t tell me it is not and it is some mystery thing that nobody else has had to deal with.
It’s bent, get it aligned, ride the frucking bike.

Yeah…I had this go weird on my road bike. I could play with the tension and H/L screws to make either the top half of the cassette work perfect or the bottom half. I really tweaked it and only a few gear combinations skipped around or mis-shifted. It was annoying.

Then I got this: https://www.parktool.com/product/derailleur-hanger-alignment-gauge-dag-2-2

It is really easy to use and I quickly found my hanger was quite bent. I straightened it up…bingo, perfect shifting. I checked all of the other bikes. Even the ones that had no noticeable problems could use a tweak. Since that, I’ve used it a dozen times, mostly on the cross and mountain bikes. So, either pay someone $20 to do it once or drop $80 and be set for life.

15

In every single case, unless the derailleur is twisted and no longer stays parallel as it moves, if you cannot tune all gears in, your hanger is crooked.
It is that simple, yet people deny this over and over again.
Pretty much every bike that comes in for service, the hanger is bent to some degree.
No they are not aligned if you bolt on a new one.
It may not be aligned if you change wheelsets and there is significant dropout wear.

But if you can tune in part of the cassette and not the rest, it is bent.
Don’t tell me it is not and it is some mystery thing that nobody else has had to deal with.
It’s bent, get it aligned, ride the frucking bike.

I thought the same as well, but typically the problem doesn’t resolve again as you shift past that point.

Given that it is occurring under load, either the cassette cog or the chain may be worn.

16

In every single case, unless the derailleur is twisted and no longer stays parallel as it moves, if you cannot tune all gears in, your hanger is crooked.
It is that simple, yet people deny this over and over again.
Pretty much every bike that comes in for service, the hanger is bent to some degree.
No they are not aligned if you bolt on a new one.
It may not be aligned if you change wheelsets and there is significant dropout wear.

But if you can tune in part of the cassette and not the rest, it is bent.
Don’t tell me it is not and it is some mystery thing that nobody else has had to deal with.
It’s bent, get it aligned, ride the frucking bike.

You mad bro?

It possibly could be the hanger; yet, the issue is all the gears tune up fine except a middle gear that clicks slightly only under riding conditions and not on the stand. I did have the Park Tool for the hanger; yet, used it so seldom that I just have the LBS check it when I go in; and, like my annual checkup, it’s fine.

I do swap cassettes and wheels though. I’m learning that a wheel swap can change the location of the derailleur in relationship to the cassette as some rear wheels are “dished” more than others. Likewise a cassette swap going from an 11-28 to 12-25 also changes the distance and angle of the gears to the rear pulley.

From Sheldon “Click” Brown
Angle adjustment (“B-tension”) Modern derailers have two spring-loaded pivots. The lower pivot, sometimes called the “a pivot” winds the cage up to take up slack as you go to smaller sprockets. The upper “b pivot” adds additional slack take-up ability by pushing the derailer’s parallelogram backwards.
The tension of the two springs needs to be balanced for best shifting.
Most derailers have an angle adjustment screw (Shimano calls it “B-tension adjustment”). This adjusts the tension of the upper (“b”) spring of the parallelogram, and thus the height of the jockey pulley. The looser this screw is, the closer the jockey pulley will be to the cluster.
The angle adjustment will need to be set according to the size of the largest rear sprocket. If you change to a cluster with a larger or smaller low-gear sprocket, you will need to re-adjust this setting. You will also need to adjust this if you change the length of your chain.
If the angle adjuster is set too loose, the jockey pulley will bump into the largest sprocket when the bicycle is in the lowest gear (large rear, small front). This is the gear you should check the adjustment in. A larger low-gear sprocket may require a different rear derailer, for enough angle adjustment to clear the sprocket. In extreme cases, such as with a Shimano 36-tooth sprocket, a longer angle-adjustment screw may be needed – some people even install the screw backwards.
Since a derailer shift is caused by forcing the chain to run at an angle, the greater the angle, the sooner it will shift. The closer the jockey pulley is to the cluster, the sharper the angle will be for a given amount of sideways motion of the derailer. Thus, the looser the angle adjuster screw is, the better the shifting will be.

17

In every single case, unless the derailleur is twisted and no longer stays parallel as it moves, if you cannot tune all gears in, your hanger is crooked.
It is that simple, yet people deny this over and over again.

I can’t make a blanket statement but I’ve had this happen twice: I’d exhausted all possible avenues and then I checked the hanger…

18

In every single case, unless the derailleur is twisted and no longer stays parallel as it moves, if you cannot tune all gears in, your hanger is crooked.
It is that simple, yet people deny this over and over again.
Pretty much every bike that comes in for service, the hanger is bent to some degree.
No they are not aligned if you bolt on a new one.
It may not be aligned if you change wheelsets and there is significant dropout wear.

But if you can tune in part of the cassette and not the rest, it is bent.
Don’t tell me it is not and it is some mystery thing that nobody else has had to deal with.
It’s bent, get it aligned, ride the frucking bike.

Yeah…I had this go weird on my road bike. I could play with the tension and H/L screws to make either the top half of the cassette work perfect or the bottom half. I really tweaked it and only a few gear combinations skipped around or mis-shifted. It was annoying.

Then I got this: https://www.parktool.com/product/derailleur-hanger-alignment-gauge-dag-2-2

It is really easy to use and I quickly found my hanger was quite bent. I straightened it up…bingo, perfect shifting. I checked all of the other bikes. Even the ones that had no noticeable problems could use a tweak. Since that, I’ve used it a dozen times, mostly on the cross and mountain bikes. So, either pay someone $20 to do it once or drop $80 and be set for life.

+1 on this. First step for adjusting a rd is to check the hanger alignment. You can’t get it right by eye balling it, you need the tool.

Electronic shifting is pretty forgiving compared to mechanical when the hanger isn’t aligned, but a welll aligned hanger is still important.

19

I forgot about checking the hanger. For my Tri bike it is a moot point since it doesn’t have a replaceable hanger since if it’s out there isn’t anything I can do about it. For my other bikes that isn’t the case and I do own have my own alignment tool for that reason.

20

+1 on this. First step for adjusting a rd is to check the hanger alignment. You can’t get it right by eye balling it, you need the tool.

Electronic shifting is pretty forgiving compared to mechanical when the hanger isn’t aligned, but a welll aligned hanger is still important.

You can’t straighten it by eye, but you may be able to diagnose it.

Before I got the tool, I just replaced the hangers if shifting got really bad. I popped off my hanger and compared it to a new one. The hanger design has a flat back plate. The new one sat flat on a table while the old/bent one looked the same, but rocked back and forth on the supposedly flat face.

So…If yours also has a flat back or front, you could take off the hanger and set it on a flat table top. Is it flat?

BTW, as mentioned above, even brand new hangers all can use a tweak, but they are usually good enough that shifting is unaffected.