I use pushbike carbon fibre assembly gel. This is designed for bike frames made from carbon fibre. Although very light and rigid , carbon fibre does not like having brackets tightened around hollow tubes as they tend to crack . The gel is a paste containing loads of microscopic plastic balls. As the bracket is tightened, the soft plastic balls are crushed against the bracket and tube, creating huge friction ,without damaging the tube. Works equally well on the nordic ,or any other clamp. When you take it apart it just wipes away. Fiber Grip by Finish line is one - US made -example.