Stop in for a cup of coffee

So question to all you mid sixties (or more) gym rats out there. As a result of a lifetime of (serious not hobby) lifting weights and the subsequent joint replacements in my mid sixties I find myself migrating to more and more cardio. I am still lifting very regularly but more for range of motion than actual weight. Example: work sets on bench are just under 150 pounds, leg press sled same weight basically. Two plates and some dimes. I am getting bored. All my cardio was always on the ice, skating my nuts off playing hockey so never really focused on stationary bike as a result of skating 2-3 times per week. I find myself now perched on a stationary bike thinking to myself what is a good distance? What is a good cardio sustained HB for a guy my age? Any input gym rats?
@ZMan67S @WV64Signet @MOPARMITCH

I can't answer your question.. but if you get bored on the bike look into a rowing machine.. i switched from a bike to a rowing machine and it kicks my *** and you get more of a workout than just your legs, good for working the shoulders/back without impact..

The Concept2 is about the best home rower.. it's gym quality though