179cm, 85.5 inseam and Cannondale Scalpel Team M I am 179cm with an inseam of 85.5 so I fall into the L category just. I bought a Cannondale Scalpel team M and being very much close in between I listened to too many people and having ridden an M BMC FS02 I have decided to go for the M anyway. The Cannondale dealer here has not been very helpful. The bike is a different one than the BMC and there is a adapting time to it but would like to know if I should really go for the L as I haven't ridden it much and try get Cannondale exchange the frame. 
Anyone could give me some advice based on epxerience or expertise?
For what it's worth, I have approximately the same measurements and race on a Large MTB very comfortably. I was previously racing on mediums and doing okay, but after I saw some race photos showing how contorted I was on those bikes; it convinced me to look into racing a large frame and I've been much happier ever since. Shortening the stem drastically improved handling and flickability of the bike in the tight singletrack here on the U.S. East coast.