"I've got some good friends who own shops (either bought-in or started it themselves) and have asked around, but also wanted to ask here:"
Maybe you should start here with telling us what your friends told you.
From what I've seen of LBSs where I live and bike near in a smaller town, the man behind the counter is probably shop owner and the other guy servicing bikes in the back probably his friend/employee or maybe owns the business with the guy behind the counter.
I think the impetus to start a business like that needs some starting point, like you happen to have or inherit some premises that call for doing some business in them and also there is not a bike shop in the area and you believe one could be here. Another impetus might be coming into the money somehow that you think of 'investing' into some business and you know something about bikes.
I guess it depends on whether you want to start small, tiny and grow, of start higher up which then requires some more significant capital investment.
Many years ago I traveled in states (I lived in Canada and that's where I am now also) and on some radio station there was this guy who people calling in were asking for advices on various things in life and his replies to them didn't spare them a bit, he could even be very rude to them and put them down hard (while having good reason for treating them like that) and I believe that's why he was so popular on the show (as I gathered after listening for a while). And it wasn't that listeners reveled in somebody being put down but the guy had very good common sense, real down to earth advice to the callers in.
This guy called in and said he wants to open a car servicing shop in a small town and how should he go about it. He was told if he doesn't have the capital to invest in it, he should first go and get two or even three jobs going for some years, sleep 4 hours and work the 20, to make loads of money first, and when the guys jaw dropped, since it became obvious that that wasn't the advice he was looking for, he was asked how old he was and then told that given his age, he could endure that, and that it still will be nothing compared to when he finally starts up that business of his. Maybe some of you might know such radio show.