Hello bud, I've got loads of Cannondale mech hangers so I can supply one it's just the little holes where the allen key bolts go to hold it in place just don't quite line up so if you want to just drill 2 fresh holes in the mech hanger or the frames drop out you'd be sorted and I have got some brake bosses.
As for the size it's not you being blind it's me being a dumb ass, it's an 18"
Staf.