Translating the work of a designer directly into reality has never been easier or more cost-effective. Three-dimensional printing is a relatively recent innovation but it is being used more and more by the cycling industry to create entirely new products or to save money on short runs of expensive parts.
The technology is allowing framebuilders such as Australia’s Bastion Cycles and the UK’s Sturdy Cycles to create hi-tech designs way beyond those generally associated with artisan builders, and elsewhere has helped apply new structures to the likes of saddles and chamois pads.
‘The cycling industry very rarely develops its own technology,’ says Tom Sturdy, whose beautifully made titanium bikes include extensive use of printed parts. ‘Although, weirdly, bikes are often used as a showcase for technologies.’
Three-dimensional printing, or additive manufacturing as it’s properly known, is the construction of 3D objects using a computer-controlled machine working from a digital design.
Initially intended for rapidly creating prototypes or models, additive manufacturing was first used by the aerospace and defence industries. However, as costs and production times have decreased, it has also become a viable option for creating usable finished items.
Emerging fully formed
The form of 3D printing most regularly used in the cycling industry involves solidifying material, layer by layer, to build complex shapes. In the case of the titanium parts on Sturdy’s bicycles, this involves using a computer-controlled laser to melt powdered titanium.
‘The vast majority of metal 3D printing uses what’s known as powder bed fusion,’ says Sturdy. ‘A fine powdered material is laid on a bed, a very thin layer at a time. The thickness of this layer is one of the parameters you can manipulate.
‘A laser then melts the layer into a cross-section of the part. The next layer of powder is laid on top, and then the laser repeats the process.’
Once the build is complete, the machine’s build plate is removed and, as the unfused material is poured away, the printed part emerges from the powder. And although it’s an expensive process, it avoids the setup costs of alternatives such as forging or moulded construction.
As such, additive manufacturing lets users create complex designs in runs that can be limited to a single item – perfect for creating bicycles with custom geometry.
‘It affords me a lot more design control on a one-off basis,’ says Sturdy, whose bikes feature printed head tubes, bottom bracket and seatstay assemblies, dropouts, forks, chainsets and cockpits.
It’s a vastly different process from the tube-to-tube construction method used by most small-scale bike makers. For one thing, the fundamental design of Sturdy’s bicycles exists primarily as a digital CAD drawing. Sturdy can then tweak each part to match the bike to its rider’s requirements.
The fact that he isn’t tied to producing a set number of components means a design can be changed at any time. This is opposed to more traditional production methods, where a suboptimal design might be produced thousands of times because of the prohibitive cost of changing the tooling used to make it.
At the same time, 3D printing has allowed Sturdy to behave like a larger manufacturer. With the design of the printed parts streamlining the build process, he can spend more time developing the bike rather than fabricating it.
‘A conventionally fabricated titanium frame might take 30 hours to create,’ says Sturdy. ‘The way I’m doing it now, once I get the bits I can fabricate a frame in a couple of hours.’
As a result, he can invest much more effort in working on a bike’s fundamental design while creating a more hi-tech product. It’s a halfway point between how bigger manufacturers work, where effort is backloaded in the design process, and bespoke builders, who spend most of their time on crafting the final product. ‘It’s a way to offer the customer something cutting edge,’ Sturdy says.
Cost-benefit analysis
Of course, the machinery needed to print titanium doesn’t come cheap. Australian bike maker Bastion is extremely rare in printing its parts in-house and, with a background in the automotive industry, its designs are also predicated on using printing.
The company currently runs two Renishaw additive manufacturing machines, costing around £500,000 each. Then there’s the expense of the ancillary machines that cool the laser and process the powder, plus the furnace for heat treatment. Even the room housing the machines needs to be kept at a constant temperature.
‘It’s not like a CNC mill that you could put in your garage if you wanted to,’ says James Woolcock, Bastion’s engineering director and co-founder. The process is also slow enough to place a scale ceiling on the use of the technology.
‘Although machines are getting faster, there are fundamental limits on how quickly you can melt titanium powder. You’re not going to be making hundreds of units per day with this kind of technology any time soon.
‘Typically we do a two-day print run, so the machine will be active for 48 hours,’ Woolcock says. ‘Then once the build is cool and ready to be recovered, there’s a two or three-hour window to clean the machine and set it up for another run. You might have enough components on one build plate for two bikes.’
Taking on contract work besides its own production, Bastion runs its machines 24/7 to extract maximum value from them. On the plus side, other than simply creating complex shapes, titanium printing allows for the creation of structures impossible to build using other methods.
‘Throughout the build we have access to the inside of the component,’ says Woolcock. ‘This allows us to create a very high stiffness-to-weight ratio, whereas if you used a conventional subtractive process, like CNC machining, you’d end up with something very heavy.’
One area where the brand has pioneered is in the use of structural latices within the components to add strength, while other benefits include the ability to include threaded bosses or further details within the parts. ‘You can also combine parts so things that would have required assembly can be printed in one piece,’ says Woolcock.
Bastion uses what is essentially a lugged construction to create its bikes. Once these lugs are printed, carbon fibre tubes are then bonded into place to create the frame. A similar technique is used on the firm’s cockpits, while Bastion has recently also begun making 3D-printed cranksets.
Incredibly beautiful, like Sturdy’s machines, Bastion’s bikes occupy an elevated position in the pantheon of custom machines and are priced accordingly – framesets start from around £6,000. The inherent cost of additive manufacturing means there’s no reason to expect bikes using this form of production to become any cheaper soon.
Complex arrangements
More flexible cycling products are also benefiting from 3D printing technology. Carbon is a digital manufacturing company in California, and its printers use continuous liquid interface production to build complicated structures from a range of materials.
Unlike printed metals, these emerge from vats of liquid polymers, the qualities of which can be tailored to the product’s intended use. So far, such structures have found their way into Fizik and Specialized saddles plus chamois pads from clothing manufacturer Endura.
By creating both the materials and the machines needed for this form of production, Carbon aims to put in place a process that works for both prototyping and final production.
‘We’re ensuring 3D printing can be a manufacturing option in the same way you might choose injection moulding or other techniques,’ says Jason Rolland, Carbon’s senior vice-president of materials. ‘To do this, we needed to solve two major problems: one was print speed; the second was around materials.’
The solution was to concoct a range of resin materials that were both light and heat-curable. Opening up a much broader formulation space, this allowed its machine to print materials, including polyurethanes – a useful category of polymers that can be used to create objects both stiff and strong or soft and elastic.
‘There are three main categories where additive manufacturing can be applied,’ says Rolland. ‘One is the acceleration of the product development cycle, the second is the mass customisation of products, and the third is in this area of impossible geometries in terms of these lattice structures.’
In the latter case, complex structures can be controlled precisely. In the case of the adaptive padding on Fizik’s 3D-printed saddles, this allows them to provide the exact amount of support in each zone of the saddle while also letting air circulate through the structure.
‘There’s no way to make a lattice structure other than to use additive manufacturing processes,’ says Rolland. ‘It’s impossible for a clamshell mould to produce a lattice. But lattice structures are widely used in architecture and construction because they’re lightweight and strong.
‘With additive manufacturing you can print these structures at production-relevant speeds and with production-grade materials.’
Compared to those used to print titanium, Carbon’s machines are far less expensive and much easier to run. It rents out its most basic printers for around £20,000 per year. The printers are capable of producing both prototypes and retail products, and Carbon also runs its own production facilities for firms needing to boost manufacturing.
Here banks of machines create parts at scale, with the finished products slipping from vats of glistening ooze every few minutes. With shifting production as simple as exporting a digital file, arranging where in the world products emerge can be done in seconds.
It’s a trick that has helped the firm attract serious investment, with Carbon betting its technology can smooth users’ workflow until the jump between prototyping and production becomes almost invisible.
‘The gap in metals between traditional and additive manufacturing is significantly larger than in polymer technology,’ says Rolland. ‘I don’t think there has been an equivalent in metals that has cracked the code on print speeds, and I suspect that’s where much of the cost comes from.’
Scaling up
At the moment, 3D printing is allowing small companies such as Sturdy and Bastion to create technologically advanced products, yet the cost and speed of metal-based additive manufacturing means they’re unlikely to ever compete with larger firms in terms of volume.
By comparison, 3D printed components such as those made on Carbon’s machines are intended to showcase how easily its technology can bridge the gap between design and mass production. Yet despite the drastic differences in cost, even in this latter case it’s still primarily a choice for premium products.
However, in future, that cost might fall. At the same time, the usefulness of the structures it can produce and the possibilities of customising products it offers have yet to be fully explored. There are other areas where additive manufacturing might yet find a role.
‘I think we’re going to see a lot more integration,’ says Sturdy. ‘If you’ve got a sub-assembly that has to be fabricated or bolted together in a million different ways, then you can potentially make a costly part by printing it. If that removes the other processes it can then become financially viable.’
With the possibility of printing electrically conductive components, the technology might also help manufacturers integrate computers and screens into their products. ‘I can see technology built into the hardware being a big area of growth,’ Sturdy says.
However long it takes, expect an increasing number of 3D parts to quite literally be coming at you.
Three technologies that changed cycling
Carbon fibre construction
While inventors, including Thomas Edison, experimented with creating carbon fibre, it wasn’t until the 1960s that the UK Ministry of Defence was able to patent a reliable process for making these high-strength fibres. Once formed into shape, carbon fibre’s first application was in military jet engines. With much of the technology closely guarded, it took several decades for anyone to consider using the material to produce bicycles.
Global Positioning System (GPS)
The terms GPS and bike computer are now almost interchangeable. However the technology wasn’t developed to help riders compete for KoMs. Instead it was created by the US Department of Defense to help track battlefield assets. A constellation of satellites provide geolocation and time information to a receiver, allowing you to locate yourself anywhere on Earth.
Finite Element Analysis (FEA)
Want to understand how a component will behave before it exists? Finite Element Analysis is a method for predicting how products will react to real-world forces. Mathematical models break down objects into many finite elements, then predict the behaviour of each to give a picture of how the entire structure will perform.
Developed simultaneously in the US and USSR, it’s another technology that owes much to the Cold War. Heavily used in the space race, it’s now used to model everything from cars to handlebars.
Three technologies that might change cycling
Digital integration
Wireless connectivity means many components are now capable of communicating with each other, and there’s still plenty of scope for integrating electronics into bicycle design. For example, your bike computer could control your gears, or your e-bike motor could alert your phone when it needs servicing. There’s also the potential to build displays and processors directly into your bike frame.
Battery technology
Whether providing electricity to motors that shift your gears or to a motor that drives your entire bike, the miniaturisation of battery technology is making more design choices possible. One area that could push this further is the development of structural batteries that use carbon fibre to combine functional mechanical properties with the ability to store electrical energy. Could your frame one day store power for your computer or lights? It’s not impossible.
Planetary hub gears
Might an updated version of the technology used to switch gears on your grandad’s three-speed Raleigh be the future? Planetary gears, made famous by Sturmey Archer, have been around for over a century. However, Belgian firm Classified has recently created a lightweight, wireless hub that offers the same range as a front derailleur but without the drag associated with planetary designs, making it a viable option for racers.
Photography Adam Gasson