I've been trying to understand the issue with spindle lengths and each and every website that I read leaves me more and more perplexed. I know that is not the case but it feels as if there was some jiggery pockery behind all this. Mind if I ask few questions?
- Why do I even care about spindle lengths? While I understand that the chain should be parallel to the plane projected by the wheels but given that one would shift the gears and the chain therefore would alter its position, why do I even care about it?
- When calculating the optimal spindle length, what is the assumed chain position on the rear cogs? Should it be positioned in the middle gear? Or on the one that one uses the most?
- Manufacturers would provide the spindle length for the crankset. BUT the position of the casette -- and therefore of the chain itself -- also depends on the width of the rear dropouts. On the same bike, with the same crankset, the chain position should be altered depending on whether the rear hub is 130 or 135 mm wide. Why this factor is not taken into account in the manufacturers' specification?
- Would all spindle lengths fit all the bikes? In my frame, the spindle had 122 mm. The BB is broken now so it needs to be replaced. The crankset is Suntour Radius and I can't find any reliable information regarding the spindle length. Some sources suggest to use a 109mm. With such a short spindle, wouldn't my crankset hit the frame?
- How do I even calculate the spindle length? What do I need to take into account?
Apologies for posting so many questions but that is like a completely new territory, a terra incognita I've never yet visited.