Ranking Bordeaux and Nantes next to Amsterdam is nonsense.
Amsterdam is miles ahead in terms of infrastructure. This ranking dilutes the most important thing to get these results : good bike lancés everywhere with no discontinuity.
Disclaimer : I've built villes.plus, an open source automated evaluation of bike lanes. 100 points, compute itineraries in "secure" mode with Brouter between these points, count the % of secured km -> score.
Amsterdam tops at 8/10. Bordeaux is at 3/10, Nantes 2/10.
Fun fact Amsterdam recovers roughly 15000 cycles per year from their canal. IIRC they have a board with the number for each year
I can't speak about Nantes which I haven't visited for decades but I think it is wrong to count bikes lanes as a single parameter.
Dutch urbanists have found that bike lanes are very important when streets used by cars are unaltered. Once you implement a lot of traffic calming features and cars never reach 30kph comfortably, bike lanes aren't that important and then streets can be shared across all users.