Hi Henk,
Depending on your inseem length and your comfortable reach, you'd probably be in the range of a Medium to Medium/Large, which is where I fall. It is generally a 17" to 18" frame size. Definitely, a S/M would be too small for you, as it is about a 16" or 16.5" frame. A short inseem measurement (30" to 32") would lean towards a M, where a longer inseem (32" to 34") would fall towards the larger M/L frame size.
And the reality is that no one can say exactly what you would be most comfortable on. Some guys would rather have the smaller frame and dial it in with longer stem and riser bars, and some would rather be on a larger frame reach with a shorter stem. You are kind of in the middle, so the best thing to do would be to try to find one to ride, if possible (I know, Fat Chance, right?

)
Good luck in your search. I have been searching for the right M/L Yo for over a year now.
doug