I’ve been spending the week doing 30 minutes on the treadmill and 30 minutes on the indoor bike. Treadmill is about a 5% incline at 3.6 mph, and I do the bike in something near the biggest gear. One day the start with the bike, the next with the treadmill.
Seems to be working well. Reduces the sameness that sets in during those hour workouts. And the combination makes sure all the leg muscles get some work.
Best good wishes from sunny Kansas,