Yeah, family is one thing and we say it as matter of course no matter the form of transport. Friends to as part of a goodbye.

I am more talking about those encounters with folks who you don't know too well, who tell you to be safe when they learn you are about to cycle. Folks who would otherwise not talk to you let alone tell you to be safe except that they realize you are cycling.

Like grocery store checkout clerks, folks in the parking lot when you are unlocking your bike, folks at the gym you are walking out with who see you head to your bike. They often say "be careful" and I'll say "thanks, drive carefully' or "have a safe drive home" in reponse or something like that.
Al