Cycling and Running Up Hill

I have no real interest in road cycling but I really enjoy mountain biking . I don't find it as hard as fell running though - going up is about the same I guess, cycling uphill being faster than running until its too steep to cycle when it then becomes slower than running, as you have to drag the bike as well. But, technical stuff aside, mountain biking is a doddle on the flat and even doddler going down hill. Its strangely enough over one or two routes than I've both run and mtb'd not a great deal faster than running either.

Runners who cycle are only likely to be fitter I think if they do one on top of the other (ie not instead of the other) and are thereby doing more training. Stating the bleeding obvious, a runner who runs for 10 hours a week and cycles for a further 10 will be fitter than a runner who just does 10 hours of running. Again stating the obvious, I suspect that the runner who runs for 20 hours, compared to a cyclist who just cycles for 20 hours, will be the better runner and, if those hours are spent in the hills, he'll be better at climbing proportionate to the actual amount of time he/she spends actually climbing.