I hesitated saying this, but I thought I'd throw it out while the bike is still new and could be exchanged. Could it be that the bike you ordered is a size too large for you? You spent a lot of money for that bike, and it is still brand new so it seems to me the shop that sold it to you should be willing to work with you on it. The way our shops here work, is that the fit is performed first, and then matches are made to bikes that are likely to fit the best. As MRSR mentioned, as long as you can get your saddle high enough on the smaller frame, and could tolerate a stem 7 mm longer (diff in tt length corrected for sta) perhaps the 50 cm would be better. All I worry though is whether the 50 may have toe clip overlap based on the published tt length, and the handling may be slightly different as there is a slight diff in trail (5.9 vs 6.1) although if it were me I would find 6.1 too stable and prefer 5.9. A lot to consider. I second being fit to the madonne first. I find my fit is not the same on bikes with diff geometries, since balance over the bike is key, and how to best achieve that can vary with diff. frame geometries.