Background: Sugino RD2 single-speed cranks call for a 103mm bottom bracket which gives a chain line of 45mm, which is what I need, but there aren't suitable square-taper BBs in this size. Alternatively, I could get a longer BB and move the chain ring to the inside of the crank spider. How much longer the BB needs to be depends on how much the chain line changes when mounting the chain ring on the inside of the crank spider.
Research: In this thread, someone had a difference of 7mm. Haven't been able to find anyone else who's made this measurement for comparison. Has anyone else measured this?
Application: If 7mm was the difference in my case, does a 117mm BB with the chain ring on the inside have the same chain line as a 103mm BB with the chain ring on the outside? (14mm longer from adding 7mm to drive side and necessarily to non-drive side)
*This is for a belt-drive so the front & rear chain lines need to be pretty close, wanting zero offset, the chain ring (sprocket) is not dished, rear IGH can't be spaced, I currently don't have any of these parts at hand so I can't measure, Q-factor be darned