Originally Posted by
V-rex
I'm not a physicist, but I can't get my mind around this analysis. When you saw the scale jump to 270 pounds, (presumably by starting from a squatting position, then suddenly standing up?) you must have noticed that the effect lasted only a second or two. To reproduce it you would first have to squat down again, causing the scale to momentarily move in the other direction. Moving your body up and down in this way would seem to be just a back-and-forth transfer of energy with no net gain.
I think that if the amount of force you can generate by a leg extension is 160 pounds, that's about what you're going to get on any kind of bike. On a DF bike the effective pedaling force is ultimately limited by your weight (since anything greater would lift you into the air rather than pressing the pedal down), but since that's a higher number in your case it's basically irrelevant. On a recumbent the external limitation is the strength of the seat frame you're pushing back against.
At least these are my rambling thoughts. It's an interesting subject, and I've never seen what seemed to me to be a competent analysis of it.
Lee
It's not just limited by weight, it's limited by speed, total weight, rolling resistance and aero drag - the exact same things that power meters use. If the front wheel of a bike is parked against a wall, or you grab the front brake, in theory you could put considerably more force than just body weight on a pedal. In reality though, as soon as you start pushing, the bike starts rolling. In test results, elite riders in full out sprints/accelerations aren't applying more than 100 pounds of force on the pedal because the more force you apply, the more the pedal moves and the more the bike moves. The average rider might be applying 30 lbs or so, with a strong amateur maybe in the 50 lb range.
People can only put out a finite amount of power. You have max force and zero velocity, up to max velocity and zero force. The faster your pedal moves, the less force is on it. Anyone who thinks they are applying even 150 lbs to a pedal, all you have to do is 60, one legged, half squats (same range of knee motion as on a bike or bent) and you'll find it's next to impossible except for those with massively strong legs. And even then, regardless of leg strength, the harder you push down, the faster the bike moves and the pedal force is reduced.