Bike Size 56 or 58?

[kian777]

I'm 6' and have been riding a 58cm road bike for the past two years.

I've had no complaints and even had a professional fitting at river city bikes.

I found a used bike that I want to buy that is also a 58cm. But recently I've had a bunch of people mainly at bike shops tell me I should be on a 56cm.

I'm Looking for some advice on what I should do. 58 has always seemed to fit but maybe I'm just use to a bad fit. I can try a 56 but I'll never really know if its right until I do a long ride.

THanks for the help