For our new gravel frame model, we opted to 3D-print the yoke and the dropouts.
The Yoke
Our design requirements were clear:
• Maximized tire clearance while maintaining a torsionally stiff rear end.
• Compatibility with modern gravel-specific cranksets like SRAM AXS Wide and Shimano GRX (ended up working with road specific cranks with some limitations).
• Integrated chainstay bridge with an M5 boss for mounting a fender. Printing eliminates the extensive prep and welding work required for a traditional welded bridge, reducing labor and overall frame cost.
• Seamless passage for hydraulic lines, gear cables, or Di2 wires.
• A symmetrical design, which adds cost but simplifies assembly and reduces labor.
• A lightweight and sleek aesthetic.
Did we make it?
Yes!
Why drop the chainstays?
This adjustment gained us a few extra millimeters of tire clearance by moving the yoke further from the tire and sprocket.
Could CNC handle this shape?
No. A CNC machine cannot produce a hollow enclosed element with cross ribs. Machining five separate shells and welding them together would be prohibitively expensive.
3D printing opened up possibilities that would be nearly impossible—or extraordinarily costly—with CNC. Non-Drive Side Dropout
This part had to be lightweight and integrate a flat-mount for 160mm brakes. While CNC could theoretically manage it, the process would involve compromises: universal dropouts would have to fit all frame sizes, distorting proportions for the smallest and largest models. Since Aveiro comes in seven (!) sizes, this was not an option.
Drive-Side Dropout
The design wasn’t as straightforward as it might seem. We were creating a 2024-ready frame, so it had to be UDH/T-Type compatible. This ensures compatibility with virtually all transmissions and future-proofs the frame. With SRAM increasingly pivoting toward T-Type transmissions — where the rear derailleur mounts directly to the dropout and frame axle — our Aveiro is prepared for this shift.
In fact, this compatibility allows us to offer builds with classic SRAM AXS MTB 10-52T transmissions at reduced prices (inquire about special offers!).
Why UDH/T-Type?
SRAM's Universal Derailleur Hanger (UDH) has faced criticism for introducing yet another standard, but it’s rapidly becoming the industry norm. Many brands, from trail and XC bikes to gravel bikes, have adopted it. For customers, this means greater convenience: if a derailleur hanger breaks, you’re more likely to find a replacement at any local bike shop rather than waiting for a custom shipment.
However, designing the UDH-compatible dropout was no walk in the park. While it may look like a simple ring with a limiter knob, the technical specifications are highly demanding. Simulating all possible derailleur movements and positions within SRAM’s strict parameters posed a significant challenge. I discussed this with a few framebuilders, including the famous Californian engineer, Peter Verdone (peterverdone.com). I had asked Peter how he’d solved some of the puzzles when designing his steel frame prototypes. He said the he had to ignore or tweak certain things to make it all work the way he wants. All right then, we were not alone.
After countless design iterations, we chose to prototype in plastic before printing in titanium.
Why? Because even the best CAD models can’t fully capture the tactile experience of a real part. Holding a full-size prototype allows us to identify errors, refine details, and perfect the final design. This process—commonly used in automotive design — brings the vision to life.
We believe in this hands-on approach because we’re not just engineers; we’re bike enthusiasts who are madly passionate about creating the best bikes possible.
