Originally Posted by
Andrew R Stewart
RG- Chain line is a wonderful spec to hit spot on. But chain ring clearance with the chain stays and the ability for the ft der to travel far enough in or out are more direct to the system's working.
Although it sounds like we overlap a lotin our understanding. Andy
Loving this conversation. For those willing to continue to indulge me here (and I may very well wind up with an extra B.B. or 2 after all if this), I got an update from FSA today. The proper (by spec) B.B. is supposed to be a 68 x 103. The Q factor on this crank is supposed to be 143. Here is what I知 thinking...
I have this frame to build as a winter trainer because it was cheap and came close to matching my regular roadie (except for having 135mm dropouts). My current bike also has shorter chainstays, 130mm dropouts, and a Q factor of 147, which gives me no issues. I知 sketching this up to play with the math, but it seems that if I tried a 68 x 107 B.B. I would add 4mm to the Q factor, matching what I currently ride. As an added benefit, I値l pick up 2mm of the 2.5mm difference between a 130 and a 135 dropout on the drivetrain side. Given the longer chaintays on this frame, my conjecture is that chainline and therefore shifting should be pretty similar between the two bikes since I知 theory I値l only be .5mm off from what would be expected with 130mm dropouts, but Im stretching the distance to the cassette so flattening the chainline a bit. Sound reasonable? A fun experiment anyway.