If I want to know what gear I'm in, I look down at the cassette.

I know several riders who are in their 60s and early 70s. They ride almost every day and do lots of touring. They have road bikes, but I think most of them have bikes that are designed more for touring than racing. in terms of things like frame material and tire width. They're not the fastest cyclists I know but they're great at maintaining a pace that will let them go on for miles.