People tend to buy expensive scooters over mid-range motorbikes in Paris, which is quite the opposite of London. A popular mode is the Piaggio MP3 because it can be locked upright when stopped at traffic lights. The French seem to have an appreciation for the effortlessness of a twist-and-go bikes for city riding.
The local authorities in Paris allow bikes to park anywhere for free, as long as they are not blocking cars or pedestrians. The rule is ~2m width for pedestrians to walk past (or on narrow roads, at a minimum, enough space for a wheelchair to get through).
As illustrated in the photo you can see just how popular bikes are in this city. The sensible and realistic parking laws alone encourage more people to get on bikes.
The popularity of bikes shows in other ways also. There is virtually no congestion in Paris, even at peak times. Only a few of the main roads had heavy traffic around 5-7pm but everywhere else had amazingly light traffic for such a large city—except when a bin lorry was blocking the road, for example.
The French have a certain respect for bikers of all types—more so than many other countries, including the UK. They recognise the benefits to reducing congestion and pollution and society shows its appreciation to bikers by accommodating them in ways from which many other countries could learn.
Once last thing that was interesting to me is that, while the majority of bikes in Paris are scooters, the only others you seem to see in any great numbers are huge bikes such as the Honda Goldwing, BMW R1200RT/GS and K1600GT/L etc. Seems to be one extreme or the other in the spectrum of available models—hardly any midsize bikes.