Originally Posted by Koyote

Since you should not be supporting your weight with your arms and chest, I’m not sure how those workouts help you to stay aero. I think working on core strength and flexibility is much more important for maintaining your on-the-bike position.

Originally Posted by WhyFi

I do workout off of the bike, though not as regularly as I should, but not with the intent of helping position on the bike. As previously mentioned, you shouldn't be aiming to support upper body weight with chest, shoulders, arms, etc. Doing so is a Band-Aid, much like cyclists seeking more and more padding, via gloves and bar tape, because their hands hurt. Work on the problem, not the symptoms.

Originally Posted by Koyote

I agree with all of this. But this should be added to the conversation: endurance athletes tend to have reduced bone density, and weight training can help rebuild it -- which helps to avoid breaking bones more easily in later years. Also, core strength becomes all the more important as we age, since it aids balance and stability off-the-bike as well as on it. So, weightlifting is important to all-round fitness. Bulking up arms and chests is not really the point, but working the core, and dynamic lifts like squats and deadlifts, are good ideas.