Don't risk a DNF (or worse!) by trying to clamp a hose over a smooth piece of tubing. Even with strong, over-tightened hose clamps, a hose can slide right off the end of a tube with a smooth, consistent OD. For security, the tube needs to have a bead or hump that the hose clamp can't slip past.
This clever little tool lets you create a bead in soft metal tubing without having to invest in a big machine or an expensive tool set. The business end is sized to fit inside 5/16" or 8mm OD thin-wall tubing. Simply insert in the end of your tube and tighten the end hex. This forces a set of roller balls outwards into the tubing wall. Then use the main hex to turn the tool until the bead runs all the way around the tube. Then install your hose and hose clamp (with the clamp behind the bead, not in front of or on top of it).
Sold individually. Tubing is not included. For use on soft materials such as aluminum, copper, and brass. Not for use on stainless steel or steel brake tubing.