Originally Posted by
asgelle
But why?
Which brings us full circle to the original question - why can the OP produce more power climbing than on the flat? I'd start by looking at what's different between the two conditions. Same rider, same bike, same position assuming he stayed seated for both efforts, freely chosen cadence assuming he didn't run out of gears, the only difference is the inertial load when pedaling which then feeds into what umd posted way back at the beginning of the thread about neuromuscular demands. Although, I would add that high inertia riding (flat, downhill, tailwind) makes it easy to let up on the power for very short periods without a noticeable drop in speed (or heart rate), but a considerable drop in power.
Really? You don't notice a difference, especially if you ignore your HRM? I sure do. Nothing gets my HR up like climbing. I really have to work to hold it on the flat, but I can climb for a long time at or near LT without forcing it. I don't think it's just me, as others here have commented on that over the years.
By "inertial load" do you mean the more constant load on the chain imposed by the gradient? It does seem like the steeper the climb, the quicker LT comes. But as I keep saying, there is another difference, which is that freely chosen cadence, which the OP has already confirmed has an effect.