Originally Posted by
Frum
I actually changed the crankset, don't worry. I'd figured that a double would less spaced outward, but I'm guessing I was wrong. Though, in the big big combination on the triple this didn't happen.
It's not double vs. triple that made the difference, it's generational.
Over the years spindles have gotten shorter, with more offset built into the crank arms. This improves rigidity, and olse gives some extra ankle clearance by way of the curved crank arms. But it means that a newer crank on an older spindle will be too far out, and vice versa.