Quadlock connector hidden inside steerer tube (custom 3D print)

I'm doing a complete makeover of my ADO Air 20 folding electric bike, and I have very high requirements for the aesthetic result. I've never liked the look of bicycle accessories that clamp around the handlebar with bolts and nuts sticking out, or for that matter, those strapped with zip ties or tightening bands.
For an elegant solution to add a Quadlock mount for my phone to my bicycle, I decided to design an adapter that hides inside the head tube. To secure it, I am using a tightening screw that, when tightened, expands the diameter of the tube insert, locking it in place—and it worked out absolutely flawlessly!

Link to download: https://www.thingiverse.com/thing:6671872

Result

Tension mechanics

When the long M4 screw is tightened, the wedge gets pulled into the main piece, forcing the sides outwards. This creates very strong friction on the sides of the tube, securing the part.

Print settings (slicing and support)

To print this design, you need to add two pauses for inserting an M4 nut: one for the angled piece to screw on the official Quadlock mount, and one inside the wedge-shaped end piece. For support, you also need to add at least one support blocker in the center of the main piece to ensure that the nut can be inserted during the print pause. Please see the pictures below for a visual explanation.

Assembly

I did not design the Quadlock locking mechanism itself, as I wanted an injection-molded, strong piece for this. I do not trust that a 3D-printed part will be strong and durable enough for this purpose, as the parts are thin and delicate and receive quite some stress when riding on rough terrain. You can find the pieces needed here.

License notice:
I have been in contact with Quadlock regarding sharing a design that fits with their patented system - I thank them very much for being cool about it and allowing DIY communities to build on top of their platform! However, they made it very clear that selling these parts is against their policy, which is totally fair in my opinion. Therefore, please be aware of the license of the file, CC Non-Commercial: https://creativecommons.org/licenses/by-nc/4.0/deed.en

Please be respectful about that. 🙏