Contemplating a build using a 7900 straight-pull 20H hub. I have so far deduced that Shimano made the 7900 rear hub as standard drilled flange and also as a straight-pull 20H on Dura-Ace wheelsets only e.g., C35. The perplexing thing is that I see no part numbers which distinguish the two hubs. There is tech data from Shimano giving the 7900 dimensions but I'm guessing this is for the standard flange model which came as part of a group set. Any insight on this? Does anyone know the hub data for the straight-pull hub?
Addendum: I know it can be measured. The the exact spoke circle would, I think, have to be computed using the polygon formed by the five spoke anchors. This is a polygon inscribed in a circle with the veritices on the circle. We're solving for the circle perimeter only knowing the length of the polygon sides. I can't find or recall the procedure for that. I think this what was called "squaring the circle" (impossible). Any math types feel free to weigh in there.