Originally Posted by
MaximRecoil
No, you can't. You can achieve the same amount of work on any weight bike, but that doesn't mean the "workout" is the same. For example, if you bench press 300 pounds 10 times, you're doing the same amount of work as bench pressing 100 pounds 30 times, or 50 pounds 60 times, but they aren't the same workout, because the body responds very differently to them. Likewise, riding a 30-pound bike 1 mile is the same amount of work as riding a 15-pound bike 2 miles, but it isn't the same workout, i.e., it doesn't have the same effect on the body. Working with heavier weights tends to increase muscle mass while working with lighter weights tends to increase muscle endurance. Many people incorporate both types of workouts into their routine.
This topic was worked over in a lengthy thread a month or so ago. The more experienced cyclists contributing to that thread pointed out that, because cycling is an aerobic rather than an anaerobic activity, the "heavier bike/harder workout" argument represented faulty reasoning: you can perform as much or as little work as you like on any bike, regardless of its weight. In fact, most of us who have a stable of bikes to choose from do our hardest workouts on our lightest bikes, because they're so much more fun to ride at high speed than the others.
In any event, look around you the next time you're in an area with a lot of bikers. You'll notice that the people on the heaviest bikes are cruising along casually and that those on the lightest bikes are working hard.