I just recently bought a bike that, it turns out, I don't like. Just isn't the right bike for me and the style of riding I do. So I've been looking at other bikes and everyone that fits me tells me I need a 56cm bike. The one I bought is a 56, but I don't think that's the problem with it. It's more of an aggressive racing frame with too high gearing. I'm 5'10.5" with a 32in inseam.

So here's the weird thing. The bike I have had for awhile that I really like and feel comfortable on is a 58. The 56's that I've tested felt good too. Is this unusual? When I get a new bike should I stick with the 56 that everyone is telling me is right for me, or do I stay consistent and go 58?

The 58 I have is a Trek 1.5. I'm looking at getting a Cannondale Synapse carbon. Do different companies' bikes just fit differently even though they're the same size? I need 2 roadies because I have 2 residences and don't want to lug my bike around all the time.