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.