Continuing the discussion from Stop race category cheats - opinions?:
One solution in the UK would be to use a look up system back to something like Cycling Time Trials or British Cycling results and see how individuals perform there.
I looked up two or three top 10 riders in today’s BC TT and they have not gone sub 20 not got any where close to to it, yet produce 5w/kg in a Zwift race!
Zwift need to verify riders results.