I have been an avid weight lifter for many years. However as I get older I find I get more enjoyment and better benefits from increased riding.
The problem is I'm not really sure what I should be doing on my off days with regard to legs. Any insight would be great. Squats? Lunges? Calf raises? Heavy iron or none?

Thanks in advance.

Cyclists generally do more lifting in the winter months, and less in the summer (when they're out more on the bike). Most cyclists also want to avoid bulking up (big biceps and chest won't get you up the mountain!).

But, as we age, we need to maintain muscle mass, so lifting year-round can be useful.

At 54 years old, I try to get in 2-3 short (half hour) lifting sessions per week. For lower body, I do deadlifts and squats (should probably do lunges too). For upper body, bench press, flys, military press, shrugs, lat pulldowns, etc. I try to keep weights low and reps high (around 15-20 reps per set), to avoid bulking up.

I follow a similar routine to SSP. I do deadlifts and bodyweight squats because I cannot afford to be sore for cycling season. I lift 'heavier' for my upper body workout. I only do 1-2x fullbody a week, just concentrating on maintenance, and will probably focus more on making gains during the winter.

What's your goal?

Muscle hypertrophy and the accompanying strength gains or increased endurance?

My feeling about off days are just that, off days. No cycling, running or weights. These are days for your body to recuperate.

In season you can do 2 fullbody workouts a week, I would do them on day that you are not planning on doing intense riding, and in season I would focus on unilateral leg work lunge variation...and you can keep the leg volume low maybe 5-6 hard sets a workout and that'll atleast maintain muscle mass and strength.

Good question. I feel like my legs are plenty strong right now. So I'd like to increase endurance.

Increase your mileage, pure and simple. "Off" days aren't really required if you aren't sick or injured.

More endurance = more miles. Weight training decreases mileage. I lift in the winter, high reps, because I'm old and because I want more strength, too, but can't ride much during the week in the winter. I don't lift in the summer after early June, because then it's time to start climbing workouts. But nothing makes you stronger than long high-mileage rides, meaning rides in the mountains of 50-100 miles or more, or 150 miles or more on flatter terrain.