I just had to pay a 90 euro fine for speeding whilst on the Bike just outside Grasse on the Route Napoleon, letter arrived, paid over the internet job done, fairly painless but first time its ever happened to me despite going over twice a year, will just have to be more careful and aware in future.
The French gouvernment very kindly provide a map showing exactly where speed cameras are located throughout France, you can even search by department so find all the radar locations along your route.
https://radars.securite-routiere.gouv.fr/#/
Someone who lies about the little things will lie about the big things too.