I've been struggling a bit with the angle of the dangle of a Nuovo Record derailleur I put on my Gitane TdF using my custom parts. Fine tuning it and using some NOS Simplex stop plates I obtained. I took a protractor to my two bikes that have Record derailleurs on them and note they both sit at approximately 63 degrees in relation to the chain stay. My question is, does this angle seem written in stone for single parallelogram rear derailleurs, and, why is it important? I presume Campagnolo designed their dropout notch for the derailleur to sit at exactly this angle. What does it affect if the angle is slightly more perpendicular? Chain wrap? I got the angle more acute using my custom made stop plate but am having trouble with the angle being a bit too obtuse using the Simplex plate. Does this angle matter all that much?