Originally Posted by igknighted

As a general rule, racers will find that buying the smaller bike and making it longer gives them a better range of fit options, and handling characteristics that are preferable for racing. At the same time, a rider who is just looking to get out and enjoy the ride will likely do better buying the bigger size and shortening the reach if need be. One of the major determining factors for me is how hard you plan to push down on the pedals.

A racer will plan to put a lot of force on the pedals a good portion of the time, and because of this the legs will take a lot of weight that would go to the hands. As a result, you can ride a lower front end position without adding any weight to your hands. Also, a racer will need to get up and sprint. When sprinting, a higher bar/torso setup makes it difficult to get leverage to apply as much force as possible to the pedals. A smaller frame size with a longer stem keeps the rider low over the front wheel to increase steering responsiveness, and allows a lower bar position due to shorter frame stack.

A recreational rider is not typically putting as much force to the pedals, meaning that same low position results in more weight for the hands and back to support on their own. The bigger frame has a taller head tube, so the bars are easier to mount higher. Also, how the bike sprints is usually much less of an issue. This position will generally have more forgiving handling as well. Imagine you ride through a patch of sand... you will be more likely to emerge out the other side unscathed if you shift your weight back (which a larger frame size & shorter stem will help do), and this holds true to most handling situations that can get novice road cyclists in trouble.

In the end, your shop is right. You could ride either bike, and in most cases you would never look back and think "what if I got the other size". Judging by your comments, it seems you enjoyed the feel of the 54 better, so I am curious as to why you then ordered the 52... is there something that felt better about that size that you haven't mentioned yet?

PS - would it be the end of the world if you rode a 56 around? Not really. But for someone who thought the 52 was a better fit than the 54 to all of a sudden want a 56 would be a huge red flag to me. Your pictures above do give a vague idea of what your position is like, but there are too many variables in distance to subject and angle that I wouldn't draw any in depth conclusions about what adjustments I would make... but I see nothing at all in those pictures (and more importantly how you felt about each) to suggest trying a 56.

Since you are looking at Specialized, your shop almost certainly has a BG fitter. Talk to him or her. The shop clearly is not trying to simply sell you inventory that they have, as they are ordering either size anyways, so I would feel pretty confident that they are (1) unbiased enough to give you straight answers, and (2) in a better position to give you real answers than a bunch of people looking at one tiny snapshot online.