I purchased a large handful
"I purchased a large handful of these because the Deore 11-51 cassettes I purchased several years ago had cogs that were repeatedly coming loose on steel DT Swiss HG driver bodies - even though the lockrings remained tight. I even overtightened the lockrings in an attempt to fix the problem, but this had no effect. Interestingly, the same cassettes had the cogs loosen when installed on a Hope Pro4 aluminum HG driver body - but it took much longer to happen. Yes, on the Hope hub I installed the spacer behind the cassette which accounts for the difference in width between 11 speed road and 11 speed mountain. Recently I installed a newer Deore 11-51 cassette on one of the wheels with a DT Swiss steel HG driver. I knew the Deore cassette I installed was newer because it came in Shimano’s revised packaging. To my surprise, this cassette never had any cogs come loose. After carefully inspecting and measuring all of the components of the newer and older cassettes, the only difference I could find between the two was that the newer cassette came with a lockring that has a thin washer installed on it, whereas the older cassette’s lockring had no washer. So I used one of these XT lockrings, which has a thin washer installed on it, in combination with one of my older Deore 11-51 cassettes on a DT Swiss steel HG driver which previously had the cogs coming loose repeatedly - and it fixed the problem. I have ridden this combination for hundreds of miles in rugged terrain and all of the cogs have remained tight. I can only guess that the shim-thickness washer on the XT lock ring takes up enough space to keep the cogs from being able to loosen. The XT lock ring is also of higher quality and has better fit and finish than the Deore lockring it replaced. I realize that you can purchase the washer alone, if you can find them. The ones I found were a bit overpriced and Cambria had a very good price on lock rings with an installed washer, so I purchased these. In my history of working on bikes, I have seen these thin washers mangled when I have removed cassettes. No problem when it’s worn out and being replaced, but less optimal when you’re planning to reinstall everything. In the past I’ve gotten away with just discarding the mangled washer and everything still worked fine, but my recent experiences have caused me to reconsider how useful this little washer might be. I’ve heard other bike mechanics say that it’s worth putting a little dab of grease on both sides of the lockring washer before assembly, so that the lock ring can be removed with less chance of damaging the washer. I guess I’ll find out if that works eventually. If it doesn’t, hopefully I’ll be able to find the spare lockrings hidden in my parts stash."
