I'm 53 and, as I got older, I cut back on the heavy weights and keep my lifting workouts to 45 min or so and only 2-3 days a week. I don't work the quads as much because they tend to gain size during riding season but I do work the hamstrings and calves. For the upper body it's a general workout with some emphasis on shoulders and upper back/traps to help the neck while riding. After reading a study that cyclist tend to lose bone mass as we age I decided keeping weights in my workout program was important. I definitely went lighter with weights (and more repetitions) as I've gotten older as years of heavy weights and their effects on my joints became a little more apparent.