Both compression rings can work. The plastic one seems to fit better for most, so preferably use that one.
So I started assembling the bike and everything went well so far. I've used the plastic ring and it works. Shifters are attached without spilling too much oil and making a mess like last time I've done a build. Rear derailleur mounted, crankset, seatpost and saddle. Yesterday I've went ahead and tried setting up the rims, which resulted in following problem:
I'm running Elitewheels 45 Edge-Gravel wheelset which are hooked and have an internal width of 24mm. In the front I mounted a 2.2 Conti Raceking and 2.0 in the rear. After initially setting the tyres without sealant, everything went well. Then I started handling the mess and added sealant to the front wheel. This is my first time running tubeless btw. I didn't make a huge mess to my surprise and even tho I had some spillage, I was able to clean it very quickly. I pumped up the tyres to 3.5 bar / 65 PSI which isn't the max. printed on the tyre sidewall. Didn't hear a loud pop, but everything looked fine.
To give the tyre a good spin to properly distribute the sealant, I mounted it on the bike to avoid doing it by hand. I've noticed that the front wheel still had a little wobble, so I thought it isn't perfectly seated. After demounting, I gave it a few pumps with my floor pump, so not overly exaggerate the pressure and I've heard these little pop sounds I'm familiar with and was sure, that the tyre is now seated correctly. A few seconds later these horrible cracking sounds started, continously without any pauses. In panicmode I tried to deflatet the tyre, but I was so shocked what just happened. I've never heard something like that. I demounted everything, checked the tyre and the rim. The rim has no visible cracks, no damages on the inside or outside and when I give it some thumb pressure on the sidewalls, I don't hear any delayering or cracking.
I've used the tubeless tape supplied with the wheelset. The rims are carbon btw. Did I destroy my wheel, or is it something someone has also experienced? I'm still a bit shocked and worried.
EDIT: Definitely something happened to the rim, it's out of true now.