https://www.zwiftpower.com/rankings.php
Zwiftpower has upgraded their ELO based ranking system and in near future KISS races intend to use these for Cats instead of the current w/kg system.
There is a basic FAQ on their page which gives an understanding of how things work. Cat A 2500+, B 2000+, C 1500+, D 1000+. From what I understand your initial Cat placement is determined by your best 95% of 20min in a race. You stay in that Cat until either upgraded or downgraded. However, there is an overlap of Cat boundaries. For example suppose you did 4w/kg (95% Cat) in at least one race, then you are automatically assigned Cat A. You stay in Cat A unless you lose 500 pts, i.e drop below 2000 points. Similarly suppose you are Cat B; you stay in there unless downgraded by losing 500 points taking you below 1500 or you gain 1000 points to get an upgrade which requires a ranking of 3000. So those in Cat B could stretch from a ranking of 1500-3000 if I've read it correctly. It's still in Beta at the moment so will no doubt be fine-tuned before implementation.
Personally, I like this a lot. Glory hunter sand baggers will naturally find their rightful Cat over time. Everyone will gravitate towards their proper level assuming they stay active. Not a perfect system but one that should lead to fairer racing.
What do you guys think? Are you in the correct starting Cat?