It always feels to me like the UCI isn’t so much trying to catch someone, as being seen to be trying to do it. On balance they’d probably be better off keeping stumm. Logically, if stuff like this were going on, it’d be very hard to keep secret. Just about the only way it could work would be for an individual rider to somehow modify their own bike secretly, or have a pet, tame mechanic who’d somehow do it for them and then hope that no-one else ever noticed. If it were a team thing, it would basically be an existential risk, with a worrying number of people knowing about it.
