Originally Posted by
jgwilliams
As far as I'm aware the chain rings are not narrower for 11-speed, the distance between them is. 11-speed chains have the same internal width as 5-speed, but the chain has been made narrower with thinner plates and shorter rivets. So you can continue to use the same chain-rings. It may even work as is but I presume there will be a greater risk of the chain slipping between the rings.Or it might be that an 11-speed front derailleur won't have sufficient throw to make the changes.
Yes you are right. So the task is to install the 11 speed chain rings so that they sit as close to each other as they are designed to be, thereby eliminating the risk of the 11 speed chain falling between them. I'm wondering if using chain ring bolts and spacers intended for the new chain rings (instead of those original to the 1970's crank) will achieve the proper spacing.