Distance between attachment holes (centre to centre): 16mm. Bracket is curved where it attaches to the frame. It's designed for seat tube diameter of 34.9mm but looks like it would work OK on 31.8mm seat tubes also. Derailleur attachment slot is 20mm long and it its top is about 5mm below the top of the top attachment bolt hole. This sits lower than the TCR front derailleur plates as it is designed for compact cranks, with relatively small chainrings. Weight: 17g (including attachment bolts).