Basic Trope: Any instance where a character goes on a bike, skateboard, etc. He or she will have safety gear on. Always.
Straight: Billy and Sally always wear a helmet when biking.
Billy and Sally wear not only a helmet, but knee and elbow pads too, and they are only riding down the street.
Billy and Sally wear helmets for anything that they think might even be slightly dangerous. About to do some cooking? Put on a helmet. Going out to get the mail in the snow? Put on a helmet. You can never be too prepared.
Downplayed: Billy always wears a helmet when biking, but Sally thinks she's too cool for that and only wears a helmet for stunt riding.
Billy and Sally are BMXing, the law demands it, or are riding motorcycles.
Or alternatively, Billy and Sally have had bike accidents before and would rather avoid getting hurt.
Inverted: They wear helmets all the time, except when they're riding bikes.
Subverted: They're wearing hats that look just like helmets, but they don't function as one.
Double Subverted: It doesn't look like Billy and Sally are wearing a helmet, but their hats double as helmets.
Billy and Sally are two nerdy kids; while the rest of the "cool kids" ride without gear, they are wrapped up in bubble wrap.
Billy and Sally survived falling off a skyscraper in the first episode completely unharmed due to their powers protecting them from non-magical damage but still wear helmets while biking, flying under their own power, and riding in a car. They do it because of the censors.