What's the best bicycle shop in town?

It really depends on which bicycle shop is closet to where you are. All of the ones mentioned about are pretty good. I've heard rave things about Reser Bicycle Outfitters, as well as good things about Campus Cyclery. Montgomery Cyclery has multiple locations in the Cincinnati area, so might be a good option for your location.

There are a number of really good bike shops in Cincinnati. I've shopped before at Montgomery Cyclery in Montgomery, they've been around for years and also have a number of locations throughout the Cincinnati area. If you're looking for a good bike shop closer to the City, then you can check out Campus Cyclery on McMillan near the University of Cincinnati. I also really like Reser Bicycle on Monmouth Street in Newport, Kentucky. They are friendly, knowledgeable and right across the river from Downtown Cincinnati. Reser also just opened a location in Over-The-Rhine, but I haven't been to that location yet; I'm sure their service at their new location is just as good as at their original location.