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Once solely the stuff of dreams, prototypes, and engineering experiments, metal 3D printing is finally starting to trickle into bicycles that people can actually buy. Moots and Reynolds both previewed 3D-printed dropouts at this year’s North American Handmade Bicycle Show, while two builders — Bastion Cycles and Métier Vélo — have based their entire frame designs around the technology. What once was the subject of science-fiction movies is quickly becoming reality, and an entire new world of possibilities has opened.
Fully custom geometry from Bastion Cycles and Métier Vélo
It still isn’t practical to build complete frames on a 3D printer. The printers are too small, for one, and there’s no advantage to using the technology for simple tubular structures that are better served by more conventional manufacturing methods. However, that hasn’t stopped Bastion Cycles and Métier Vélo from using 3D printing where it makes the most sense: at the joints.
Both companies are taking a similar approach, using 3D-printed 6/4 titanium lugs bonded to pre-formed carbon fibre tubes. The benefits are the same from either outfit: the possibility of fully custom geometry with no additional tooling costs, along with the ability to create structures that otherwise wouldn’t be possible (or practical) through forging, casting, or machining.
“Performance-wise, [3D printing] enables us to really manipulate not only the external shape of the titanium to get stiffness and strength into it, but on the inside, we’re able to manipulate the structure with things like lattice work and ribs and variable wall thicknesses to put the strength where we need it,” Bastion Cycles co-founder and managing director Ben Schultz told CyclingTips. “This means we can achieve the weight and stiffness and strength of a carbon bike, but using titanium, which, when we use it selectively at the nodes, actually creates a better ride comfort than if it were carbon fibre.”
Indeed, Bastion Cycles’ single initial model — a disc-brake equipped road bike — could easily pass for a moulded carbon composite frame, had the company chosen to cover the structure in paint. The printed titanium lugs are artfully sculpted with character lines rarely seen in metal frames and a surface finish that’s remarkably smooth for a printed part. Those lugs are then bonded to filament-wound carbon fibre tubes.
Métier Vélo, on the other hand, still highlights the lugs’ 3D-printed origins, but with shapes more reminiscent of classic steel with scalloped and pointed sleeves as well as the company’s stylised fleur-de-lis logo integrated right into the surface of each lug. While the adjoining tubes are still carbon fibre, Métier Vélo founder Jamie White has opted for roll-wrapped tubes from Rock West Composites, located nearby in South Jordan, Utah.
“[3D printing] is total design freedom,” White told CyclingTips. “This kind of approach is ideal for small custom builders because it costs the same to do one bike as ten bikes. There’s no real economy of scale.”
“One thing I’m offering is free repair or replacement,” he added. “If anything happens to the frame, I just want people to bring them back. [Repairs are] pretty easy to do. If there’s a dinged carbon tube, I can just replace the tube and if there’s any titanium damage, I can just reprint the parts. It’s a nice way to build a bike from a repair and durability perspective.”
White takes a consciously conservative approach to his frame design, using lugs that he considers “overbuilt” by supplier GPI Prototype & Manufacturing Services, with wall thicknesses ranging from 0.75mm to 1.5mm depending on location. Likewise, whereas many carbon fibre frames have paper-thin tubes you can literally squeeze between your fingers, the tubes White sources from Rock West measure a stout 1.3mm. Even the bond surface areas are three to four times what White considers to be necessary for the applied loads.
“The software package I use has some finite element analysis in it,” he said. “All of the lugs are way overbuilt. That’s one of the things I consulted with GPI about. The modelling I’ve done shows that the carbon tubes will break before the bonds or lugs give out.”
White has some destructive testing planned for later this year that will likely allow him to pare his frames down a bit, but even then, he doesn’t plan on ever catering to weight weenies.
“Because I use more more titanium and carbon than is minimally necessary, my frames probably won’t ever be much below 1,100g or so,” he said. “There’s about 400-600g of titanium, and the rest is carbon. My goal is to make tough, durable, and repairable frames that perform well. If someone wants a 550g climbing frame, I am not their builder.”
Based in Melbourne, Australia, Bastion Cycles is being far more aggressive in what it can produce, using lugs with walls as thin as 0.5mm while also incorporating ribs, cross-members, and lattice-like internal structures that it says adds measurable strength and stiffness. Claimed frame weights are impressively light, right around 1kg — a substantial 200g lighter than Métier Vélo’s. However, Bastion is more comfortable flirting a little closer with the edge of reliability thanks to a full battery of in-house ASTM durability testing, a distinct rarity amongst the hand-built crowd.
Bastion Cycles is also highlighting the capabilities of its flexible manufacturing techniques with an extremely clever online configuration tool that lets potential buyers customise their frame’s geometry and build kit as well as its ride quality, stiffness, and projected tire clearances — all with an instant estimate of the final frame and complete bike weights. The online tool also generates a nifty graphic that visually compares the current selection with other well-known industry benchmarks.
In either case, riding on the cutting edge of bicycle frame manufacturing technology won’t come cheap. Métier Vélo is currently selling its frames for a whopping US$8,500 with a Chris King bottom bracket and headset; Bastion Cycles’ frame is a comparative bargain at AU$7,500 including a Whisky No.9 carbon fibre fork, headset, and bottom bracket.
3D-printed dropouts from Moots and Reynolds
Moots and Reynolds also showed off 3D-printed bits at NAHBS, and while neither project is quite as ambitious as what Bastion or Métier Vélo showed off, you’re far more likely to see one of these out in the wild. Both are being printed by i2M in Birmingham, UK.
Moots is using the technology for flat-mount, thru-axle rear dropouts on its latest disc brake-equipped road, gravel, and cyclocross frames. According to company president Butch Boucher, the 3D-printed dropouts not only feature internal structures that wouldn’t otherwise be possible using more conventional manufacturing techniques, but they should also make for more consistent final products.
“The thing that we were really challenged by, looking at flat mount, was that it would be asymmetric in terms of where the welding goes on the chainstay,” said Boucher. “All titanium expands and contracts when you weld it, and it also contracts more than it expands, so it’s going to move if you’re asymmetrically doing something. So here we have an opportunity to symmetrically weld — we can maintain alignment through the whole process so much better.”
“The consistency of the product is our biggest goal,” Boucher continued. “We make quite a few frames a year relative to everyone [at NAHBS]. When you’re doing onesies, you can kind of manipulate things and deal with them one at a time, [but] we need to have a consistent product from start to finish. It’s like a chef in a big, good restaurant. He’s got a crew on the line that he knows is going to create a consistent product. Part of that is what the recipe is, part of it is the ingredients, and part of it is the skill set of his crew. To have it be the same every time is the biggest challenge we face.”
Similarly, Reynolds is also using 3D metal printing to produce flat mount-compatible rear dropouts, although in this case they’ll be offered in both 6/4 titanium and steel — in both thru-axle and quick-release wheel interfaces — and they will be available to any frame builder who is interested in using them. According to Reynolds, its new 3D-printed dropouts will offer strength comparable a 2D-forged part along with drop-in compatibility with existing frame building fixtures.
Reynolds hopes to have them available to builders as soon as April or May, at a cost of around US$180-200 per pair.
Moots isn’t offering its dropouts to other companies, but Boucher says that while they’re not exactly inexpensive to make, they likely won’t add much — if any — cost to end consumers.
“If it’s not net zero, it may cost us just a little bit more. It’s not cheap but it saves us multiple steps.”