I got a cheap mountain bike and started riding the local bike trail. There's a couple of little rises on it, not exactly hills, but still goes uphill there. And I'd have to downshift and huff and puff going up. Then after a while, I got to where I didn't need to downshift, then I could go up them in high gear (wasn't that high on that bike) and without slowing down. It just takes a while. You get some fairly fast improvelment just from toning up your muscles.
I think it depends too, on how you're built, with size of legs versus body size.
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"be careful this rando stuff is addictive and dan's the 'pusher'."