Ride the bike in French

Question

usually we say : Je fais du vélo  OR  Je roule en vélo?

Accepted Answer

Bonjour Lixin 
"The basic rule is fairly simple: if you can go into the vehicle, use en – otherwise use à.en bus, en avion, en train, en voiture, en bateau…à moto, à vélo, à pied, à trottinette…"
The above Is from WorkReference.com 
I could not find a post more appropriate to your Kwiziq query than the quoted lesson.
Hope this helps.
Bonne continuation
Jim

Answer

Bonjour Lixin,
Jim is correct as to the use of "en/à + [means of transport]". Eventhough, it is grammatically correct to use "je roule à vélo", it is far better to use "se déplacer" (= to journey/travel) in this instance:
Je me déplace à vélo. = I am travelling by bike. 
I hope this is helpful.
Bonne journée !