I definitely qualify to post in this section being over 70.

If other things allow (weather, being at home etc etc) a pedal out would be hopefully 30.km that will include several Km of decent hill climb which is more strenuous than just flat pedaling, using one of my road bikes of course.

I also pedal off-road on farm gravel trails, this is predominantly flat ground so here 30.Km is a good run out on my Scott hard-tail.