Help me diagnose sound coming from new 12 speed Ultegra
 

Happens in 5th cog only. Constant clicking. Bike shop has no clue everything is brand new and has been checked and adjusted. I’ll upload video onto YouTube and share link.

bad chain?

Mine does the same ..... Posted Here
2022 Cervelo R5 delivered with Ultegra 12sp Di2 52/36 & 11-30 Ultegra Cassette

Even before I rode it, changed it to 50/34 & 11-34 Ultegra Cassette
Rear cog #5 (21Tooth) clicks in both big & little ring. It is the only cog that does it.

Asked Shimano for a Cross ship (covered by my visa) but all I could get was an RMA.
Not a great offering for a Cassette I'm using.

So I purchased a Dura-Ace 12sp 11-34 ....... drum roll please ...... It clicks on the same cog, but a little more quiet.

I'm open to suggestions that don't begin with "SRAM". 8-)

Barry

"cam"?

If it is only a suggestion… shift to the 21t and see if you can use the barrel adjuster to dial it out. If you can and it clicks against the 24t check to see how much tolerance you have going towards the 19t, or vice versa.

From exploded views of a Shimano 12 speed cassettes I think the 5th position cog is an individual cog (not spidered). If it is, you can measure the spacers and flip them or replace one with a slightly wider one. You should take a corresponding amount off the spacer on the other side to keep the index consistent with cogs 6-12.

I can’t say it will fix it, especially 12 speed spacing, but I’ve done this every now and then with an 8/9 speed and a renegade spacer.

John

Ticky tick tick tick!
 

Mine seems to be missing the barrel adjuster. :)

So I've previously ridden along in Cog5 (21T) with E-Tube App in my other hand, making RD adjustments as I bike along.
Between touching cog 4 and touching cog 6 there is no point where cog 5 does not tick twice per revolution.

Regarding spacers, bear in mind this is now TWO bikes and THREE Cassettes, Two Ultegra and a Dura-Ace.

Barry

Questions
 

The_hump_ ,
1. What bike are you having issues with ?
2. Mechanical or Di2 ?
3. Does yours tick twice per wheel revolution like mine ?

Thanks

Barry

Yeah, Di2. Well if it always happens on 4 and 6, you might be able to add .1mm shim on each side. Not sure how that impacts the rest of the indexing. Maybe fudge some away between 2-3-4.

Obviously there is an RD issue or a cassette spacing issue, either by design or bad luck.

John

Di2 is the only option for Ultegra 12 speed, I think.

I'm guessing it is a firmware problem.

John,
I don't believe it to be spacing. There are many RD steps between touching cogs 4 & 6 so getting the RD into the middle for cog 5 is very easy.

If I turn the pedals manually and very slowly, I can see the chain hang on what appears to the the tooth profile and it does it twice per revolution.
I can mark the teeth with a pen, hold the cassette and rotate the wheel to any point and it's still the same teeth that hang the chain.
By rotating the wheel I prove it's not axle related.
I can use any piece of the chain and the teeth that have the issue remain the same, this proves it's not a bad spot on the chain.
I changed cassette to Dura-Ace and same issue, this proves I didn't get a bad Ultegra cassette.

Still Stumped

Barry

I know my suggestions are low tech, but if you have identified a profile at one place on a cog, I might be inclined to “very” slightly file that spot. There are very small thin files available. Or continue to live with it.

John

The OP mentioned 5th cog, but not sure if that is also a 21T on their cassette. Perhaps, the die used to cut or stamp the 21T is amiss. I realize this happened on both Ultegra and Dura Ace cogs, but perhaps the same die is used? I'm just speculating it could be a manufacturing process error.

I know the OP said not to mention the other brand S, but for the sake of science trying a SRAM cassette would be a good data point. And since cassettes are wear items, you can keep it for future use.

Or try swapping the 21T cog to the #6 position and #6 into #5 and verify the problem stays with the cog.

I think SRAM went to 13 speed not 12 speed like Shimano, could be an issue!

My 11sp Ultegra Di2 sports a SRAM 11-36 and it’s great!

Great idea, but can’t.
I wanted to grab the 21T from my unused 11-30 Ultegra. Turns out the 21T is spidered.

Barry

I did that, too. It works well.

Not sure how the 12-speed SRAM would work with the 12-speed Ultegra. It might be less tolerant.

I have the 12 speed 11-34 DA cassette (same one you switched to, I believe?) on 12 speed DA and there is no clicking in the 5th cog. Just listened very carefully for it on the stand before a ride and during a long quiet ride.

Perhaps there was a bad batch of these, and there are some shared elements or processes with the 12 speed ultegra parts?

I'm not sure how well a 12-speed SRAM cassette would work with a 12-speed Shimano Ultegra drive train.

Since the OP is running 12 speed Ultegra, the advice on what works for 11-speed might not be generalizable.

di2 12 speed. Basically twice per revolution I think. Trying to post video but can’t until I reach 10 posts.

The_hump_
So what's the bike?

Barry

12sp cassette click
 

OK, I broke down and made a video.
Enjoy
Barry



Note: Bike is upside down for ease of filming. (So being pedaled forwards)

very clear video. i went to make a similar one but my drivetrain is so disgustingly dirty compared to yours that it's barely visible what's happening. but i can't hear a click at all, this weekend i'll clean it and see if the tooth profile is as clearly different as yours is. seems like a machining problem is keeping the chain from fully engaging, and under load it gets forced into position and goes "click" ?

looks like the cavity of that valley isn't the same to the rest of the others for that cog. I bet a slightly more worn chain on that particular cog would not experience the pop when it rotates to that specific area.... although, it might not play well with the majority of the remaining valleys.

Wonder if the OEM will issue a TSB to ever so slightly file that one valley or waste a whole cassette by replacing it with another defective cassette.....

Great video. My 12 speed Ultegra does not have that issue.

But my Shimano 10 speed has always clicked twice on one middle cog and I'll use your info to see if it's from the same source, two badly cut valleys. It'll be a couple weeks before I get upstate to check this.

Is my issue also from a 21 tooth cog?..wondering if there was a bad stamper.