Garth,
I have very little book knowledge on any of your questions. That said, I think you are on to something. To this day, I believe my aluminium Simplex non-slant derailleur works as good as and usually better then any other rd before or after, slant or non-slant. Others may disagree, but I've had/ridden many makes/models of slant design rd's and really wonder what was so "improved" over the well designed, durable (aluminium, not delrin), and wonderful shifting Simplex unit.
Eric Elman
At the risk of seeming very foolish here, I am going to speak the unspeakable: What is slant that is refered to in the slant parallelogram design rear deraileur? I would imagine that the slant must be that one which causes the downward line of the rd to point more forward. If this is the case, then how was this an invention? Many rd's had at least some forward pointing slant...no? This would be a degree of forward slant then and not a whole new concept. In those beautiful old campy derailleurs, the design did seem to make them hang down straight, but the jockey wheels were still somehow very close to the cluster. The old campy rd's looked so delicate and elegant hanging like women's pendant earrings. Did the full slant design really improve things, or was it just that aluminum casting, chain design and cluster teeth just evolved so that rear shifting vastly improved? So there are three questions that are bugging me: 1) Which is the slant that is refered to in slant parallelogram? 2) Did it vastly improve things all by itself? 3) Don't high quality downward hanging derailleurs work as well or almost as well? Garth