Gary Y.wrote a review of Shimano Ultegra SM-RT800 Disc Rotor on July 7, 2019
Familiarity: I've used it once or twice and have initial impressions
I purchased these to outfit my new carbon disc wheels and they matched, more or less, the bike without issues. Or so I thought. The disc for the rear wheel and cassette fit perfectly! But the front disc would not tighten properly, even though I was using the lock ring that came with the discs. It turns out that the Enve 3.4 disc wheel with Shimano front disc rotors requires a different lock ring before it'll fit onto the bike properly. Aside from this minor issue, everything is easy to install as long as you have the right Parktool (FR-5.2 GT). I'm sure that these will offer the same great stopping power as the current discs on my stock bike wheels since they are the same.