Backed the wrong horse? We have something that might just help: Adapter D30/D28 and Adapter D30/D28.6 can be used to connect old steel tubes with a plastic sheathing (28 or 28.6 mm diameter) easily to the state-of-the-art world of Profile Tube System D30 in aluminium.
The Adapters are available in lengths of 25 and 37 mm.
Note: Please note the load limits, which are due to the use of plastic components.