How did you isolate it?

I have been unimpressed with Dura-Ace cassettes newer than 7800.
I broke the carrier on a 9000 cassette.
Even the ones that don't creak make more noise and shift less well than an Ultegra cassette.
It is 8000 cassettes for me- on otherwise Dura-Ace bikes.

The only problem I have ever had with 9000 or 9100 cassettes was when I put them on an older wheel and neglected to put on the spacer. Is there any lateral play of the cassette on the wheel?

Have you tried using a) using this wheel with cassette on a different bike and b) using this cassette on a different wheel on the same bike? Try both. Borrow what you don't have. If you get the same squeak both times then it's the cassette. If not... Maybe it's the wheel .Or three bottom bracket

Im in South America for a few weeks with limited tools. I had borrowed some bottom bracket tools and I re-installed and glued (loctite 609) the bb90 bearings in my madone 9 and 99% sure it is not the bearings, I know that this is a known issue and was the first place I looked. I know carbon fibre creak issues will most often be heard far from the actual problem but this is pretty obvious it is coming from the rear and it only happens on select gear clusters. I had tried a different quick release skewer and it did not solve the problem.

Last night I bought a cheap set of circlip pliers to remove my chain and I also used them to check my cassette lock ring and well, It was loose. I popped the cassette off, reset the end caps for my powertap rear hub, Gave the pawls a shot of dry lube, cleaned the cogs and reinstalled the cassette with good torque. The required 40nm is quite a lot.

Took it for a test ride, no creak. Although it was only a few miles I took it up a couple hills and I cannot repeat the creak which is good. I will know for sure tomorrow when I go for a good ride. Rest day today. Thanks everyone.

sounds like you are using a quick lock link? if so, i've found these to be noisy in certain cases. even the Dura Ace ones. re-installing the chain with a pin, fixed it in my cases

How is the condition of your freehub body? Any major bites showing?

Not DA, but I had a cassette creek on my road bike with SRAM stuff. It only happened on a specific cog. I attributed it to one time I experimented shifting eTap under load on a 10% hill at 400W. (I do not recommend this.) My bike made a horrible sound, and I thought I had ripped the back end off. After that, the cog I shifted into started creaking. Maybe I dug a deep bite or damaged the teeth on the cassette. I replaced both the cassette and wheels this fall, but I have not ridden yet. I am looking forward to a silent ride.

The fact that it took you so much torque is a bit worrisome. Did you install this cassette with that thin little shim in there? You might need it.

If you did already use it then ignore the rest of this but if not...

Do you have it? They tend to supply them with Shimano cassettes. They tend to be ubiquitous so if not you can probably find someone with an extra one.

Try installing the cassette with that shim. You should know right away if it belongs there or not. If not, you will have a very hard time getting the threads to catch when you try to tighten it. If so, don't try to force it.

But if you are able to get it on with the shim without difficulty that's probably the issue.

Hey thanks for the response. I didn’t use the shim, for 11 speed I almost always don’t need it. Once I discovered that the lock ring was loose, I removed the cassette for cleaning, re-installed it and applied the approximate recommended torque to my lockring and it definitely solved the problem as I have conpleted 4 rides since with no more creaks. There is nothing worse when your 10K + bike sounds horrible from creaks. Completely silent now.