The gears and chain of a bicycle are extremely high wear parts. Paint would easily flake off of these parts. This is why they are typically not painted, and even when they are, like a painted BMX front sprocket, you'll find that where the chainring and chain make contact, the surface is unpainted.
Mild steel bikes are painted to prevent rust.
Carbon fiber bikes are painted to keep the composite matrix from absorbing water.
Aluminum, titanium and stainless steel bikes don't have to be painted, but they can be to make them pretty.
Bicycles
George Mason made bicycles and painted them. he wrote the decration of rights
If the bicycles belong to ONE FRIEND, it's "friend's bicycles." If the bicycles belong to TWO OR MORE FRIENDS, it's "friends' bicycles."
The word sharrow is a cross between share and arrow. It is painted on a lane to designate it as a lane -- shared by cars and bicycles. Each can use the entire lane.
1.8 bicycles.
There is no specific collective noun for bicycles, in which case a noun suitable for the situation is used, for example a rack of bicycles, a row of bicycles, a standof bicycles, etc.
what did the ancient bicycles look like?
Bicycles weren't invented in Canada.
More bicycles
The first bicycles were powered by humans.
KHS Bicycles was created in 1974.
Bianchi Bicycles was created in 1885.