Wow so everyone has this gap? I can't imagine that it's a design feature, or what it should be for?
Luckily I have been granted the luxury of a lathe, So I guess I'll turn a piece of allu into a spacer:)
Also i rather like to use aluminum because of it's soft nature, any small errors will be "corrected" while fitting
Also also I don't like to use small surfaces(like pipe(still thankful for the suggestion wilko)) because it'll press right trough the paint.
I've checked the chain tension and there is a wiggle possible without too much force applied so i think i'm good there:)
Cheers!