It's not the offset bolt, which only applies to compacts, it's that the ring is effectively "sandwiched" between the spider and the crank, so it has to be exactly the right thickness (or a bit less, and use the 0.2mm shims which Campag supplies to take up the slack)
It's not the offset bolt, which only applies to compacts, it's that the ring is effectively "sandwiched" between the spider and the crank, so it has to be exactly the right thickness (or a bit less, and use the 0.2mm shims which Campag supplies to take up the slack)