Originally Posted by
joejack951
A 9 speed chain will work fine on a 7 speed freewheel. However, since the wider 7 speed FD cage will require a longer throw to move the chain up the the big ring, you still may have the same rubbing issue. A 9 speed FD in addition to the chain might be what's required to truly fix the problem.
Another possibility is adjusting your chainline to move the crankset away from the bike slightly. This would net you some clearance without requiring any expensive component changes (and keep the bike original). You should only need a thin spacer (0.5 - 1mm) to get the clearance you need based on your description.
Thanks for your response. You have some good ideas and I will consider them carefully. Is this problem I am having the result of outdated design (do other riders experience this on vintage SR drive trains) or could this issue be caused by a crankset with execssive flex? Are there any other possible causes I should investigate? Could I also simply resolve this by moving to Chorus 7 speed? I have a Bianchi with late 80's Chorus 7 speed and it has none of these issues.