Provide solid proof
Whenever you happen to deal with a stereotype over a certain thing or matter, always remember that providing a valid proof or whatever you say in support of your comment would be really helpful. Let us put it this ways, if a stereotype has seen that a person riding a bike without the headgear met an accident, heâd think that everyone biking without the helmet would meet the same fate. Here you can help him out by proving that riding a bike safely requires proper wits and not just a head gear. You can prove it to him by showing him people around who ride the bikes safely even when they do not put up the headgear. Such facts would definitely let a stereotype reconsider his decision and thinking.