Here we have what is undoubtedly one of the most advanced bicycle frames ever created – and yet you’ve probably never seen or even heard about it.
Produced as a joint collaboration between UK firm Mirada Pro, tubing specialist Reynolds and framebuilder Ted James Cycles, the frame is currently a one off that demonstrates a new direction for the people behind Mirada Pro.
Taken from design to manufacture in just eight weeks, the frame uses multiple 3D-printed titanium lugs that are welded to custom titanium tubing from Reynolds.
The frame has yet to be ridden and is currently awaiting EN testing
Look closer and you’ll see 3D printed titanium lugs make up the head tube, bottom bracket, dropouts and top tube/seat tube intersection. These lugs have been welded to custom drawn titanium tubes from Reynolds in a 53cm frame that emulates the geometry of a traditional alloy road bike. The result is a sub-1kg (999g) frame that Mirada Pro claims offers improved torsional stiffness over a comparable alloy item.
The design also allows for welds to be moved away from high stress areas, and for the surfaces destined for welding to be simplified. Less parts and reduced machining times mean that manufacturability should be improved while costly tooling can also be done away with.
The potential of 3D printing in bicycles is yet to be fully realised but below is a decent example of how the technology has made a big impact among other industries – this one's from the world of aerospace.
(L) CNC part is 50% heavier and wastes 68% more material than the 3D printed component (R)
The metal component to the left was traditionally CNC milled from a large titanium billet. On the right is the redesigned version of the same component, and one that’s optimised for 3D printing. Compared with the original design, the 3D-printed part offers the same strength and stiffness but is 50% lighter. Better yet, the economy of the process is on another level: the CNC process producing a remarkable 70% of waste material compared to just 2% from the 3D printed part.
Indeed, it wouldn’t be going too far to say that 3D printing is enjoying its own industrial revolution, but to say this technology will do away with more traditional manufacturing would be wrong, at least for the foreseeable future.
Restrictions with 3D printing currently revolve around the cost of the printers themselves, that and the physical size restrictions of the beds within them. Similarly, although tolerances from 3D printing are already very impressive, sometimes they aren’t quite close enough for the most demanding applications, and so many 3D-printed parts will be finished via CNC. The process isn't just a case of clicking print either, and each part will require work to assist with powder removal, heat treatment and finishing.
A different design approach
New methods of manufacture also require a new take on the design process, and this is where 3D printing really does get interesting. Suddenly, longstanding design rules have gone out of the window as shapes and constructions that would’ve previously been uneconomical or even impossible are now easily achievable.
Rather than painstakingly removing material in the correct places, software is able to pinpoint exactly where stress occurs, and demonstrates to designers where and how much material should be present.
In the case of this frame, Mirada Pro used the load figures a frame needs to achieve in order to pass EN safety tests, which engineers then input into their CAD program. The program then interpreted how much titanium powder needed to be where in a formation that would provide the correct strength but with minimal material. Just take a glance at the CAD drawing below and you’ll notice large vein-like structures that pass through the design. These structures have largely been depicted by the software used to design the frame, and you can see directly how they translate to the finished components.
Once loaded with the correct data, CAD software then determines how to go about making a strong yet light structure
Why Ti?
Cost restrictions means that conventional titanium frames are relatively rare in the cycling world although 3D printing does add an interesting spin on things. Titanium actually works out to be the cheapest material that Mirada Pro works with, even though the machines are capable of producing identical parts from alloy or stainless steel, both would be considerably more time consuming in the printer, remember - time = money. In fact, printing with aluminium takes twice as long as it does with titanium.
What goes between the lugs is another matter altogether, and what's currently filled with Reynolds titanium tubing could just as easily be carbon fibre. This brings another advantage to this design, its versatility. Tweaks at the design stage could make it possible for this frame to be totally modular: want different tube stiffness for different sized frames? easy. Geometry or sizing changes could easily and quickly be made in a way that isn't really possible as things stand. An online configurator could be made to print out a bike to your exact spec.
Mirada Pro's frame features five 3D printed 'lugs'
Who's behind Mirada Pro?
Mirada Pro is an arm of Birmingham-based 3D printing specialist Innovate 2 Make (i2M). The bulk of its work stems from the aerospace and motorsport industries, where the benefits of 3D printing manufacturing are already well established. This gives Mirada Pro a big advantage as, unlike most people in possession of a 3D printer, its team have machines that run almost constantly.
In manufacturing, time = money, and the more these machines are active, the more cheaply such parts can be produced in volume. As such, Mirada Pro insists that it could create frames and components that would prove cost effective in today's market, and that's just what it intends to do.
Mirada Pro is for now merely dipping its toes into the bicycle arena, but has strong intentions to offer a frame sometime in the near future. Interestingly, the firm is aiming to work with framebuilders rather than larger manufacturers to fulfil its short-term ambitions. It's a name you should certainly look out for in the future.
