For some people, and I hope most of the cyclists are in this case, riding the bicycle is as simple and natural as breathing, and they feel on the streets as fishes in water. Fearing is the biggest barrier for people to get on the bicycle through Parisian streets everyday, because of cars amazing ways of driving. I have no over answer than that one: "Don't worry! You can go! Everybody can do it! What you have to fear after is the pleasure you will find while being on the saddle..." Maybe not strong enough to convince?
Il faut commencer tôt!... / Starting young!...
Humain? / Human?