A great business idea solves a hole in the marketplace, creating something that solves a problem that no one had previously been able to solve. This doesn’t always mean coming up with a new idea, sometimes it just means identifying where an existing business could meet a need and starting there. That is what Shelly Walker, owner of Fairmount Bicycles in Philly did - and it paid off. Her business is more than a business - it’s a place people want to be, according to this week’s Yelp reviewer.