As a general way of looking at it, we all want our bike to have a lower gear than it does, as soon as we can't make it up a given hill in our lowest gear. What was mentioned elsewhere is also true, that you need forward momentum to assist your ability to balance. There will always be an un-climbable hill, if we care to seek it out, then we are going on a hike. And it is also true that we may experience a shortage of momentum, to the point that we can't get both feet in the pedals from a standing start before stalling between pedal strokes. We then hike some more.We sometimes need advice from our parents -- Mother Nature and Father Time. Or, a set of training wheels, which would allow us to get started with both feet in the pedals halfway up a steep hill. Once thus underway, we could benefit from the added stability they could provide. I know, the notion of training wheels is absurd! I was kidding."dabac" pretty much nails it on the head, and if it seems to be a vague answer to a rather thoughtful question, I'd have to say it is because of all the unknowns involved, due to different styles of riding, levels of fitness, and the trails & pathways we have yet to encounter. As a direct result of all the hill climbing I ever had to do, I have always looked to see if bikes had a really low gear, but I can't say that I've ever looked at any bike's drivetrain, and deemed that it had "too low" of a low gear! It may still be possible to find a cogset with a 38-tooth cog on it. One brand at least, offered some kind of "Wilderness Adventure" gearing setup like that, back in the old days. If you had a 22-tooth small front ring to go with it, you'd be the envy of the bike club!