THE DESIGN PROCESS CREATING PERFECTION.
By now it’s almost common knowledge, the material we call carbon fibre is a combination of different types of carbon filaments bonded and held in place by resin. Just as there are different alloys of aluminium and steel, so there are numerous types of carbon fibre filaments. We use various grades of Toray and Mitsubishi materials combined in different ways. Unidirectional (UD) carbon fibre has all the filaments running the same way – it's very strong in one direction, less so in others. Woven carbon has interlaced filaments positioned at 90 degrees to one another, making the sheet strong in multiple directions. It’s about using it where and when appropriate, all with the view to deliver a superior ride quality suitable to each and every bike in the range.
Design is everything
Bicycle design is a balancing act, juggling often conflicting requirements. A frame needs to handle accurately and be rigid to deliver all of the rider’ power to the road. However the frame also should deliver a compliant ride. It should be strong, yet light. And look good, too.
Each project begins with a conversation, followed by several more, honing it down to what we call ‘a precise philosophy’. Although contradicting, and verging on pretentious, it helps us set a clear direction as to how we’d like a bike to ride in the prescribed circumstances.
Then it’s time for the drawings. These then become plans and then computer models, which in turn are grown into 3D models. After more animated discussions on style and design sensibilities and most importantly, geometry, we call for prototypes to be tested in action (and punished in the lab).
Finite Element Modelling
One of the unique benefits at different types of fibre can be placed in varying orientations within a frame, putting strength exactly where it's needed. Using Finite Element Modelling (FEM) to visualise the loads on frames on computer software, we can experiment with different materials, lay-ups and structures without having to build numerous physical prototypes.
With FEM, we can simulate the loads from riding and see exactly how those loads will affect a frame design. This step is essentially Finite Element Analysis (FEA), which not long ago was state of the art. FEM goes further, though, allowing us to add, remove or change material and refine the design virtually, testing as we go along. Once a frame design is performing as we want it in FEM, we know it's worth making a physical prototype for real-world testing.
EPS Moulding System
Making a carbon fibre frame involves compressing layers of carbon weave and epoxy resin into a mould to get the desired shape. Traditionally, inflatable bladders are used inside the frame to force the material into the mould, but because the shape of a bladder can't be finely controlled there can sometimes be wrinkles or inconsistent thickness in the finished frame. To avoid this, we use expanded polystyrene - essentially the same stuff that cycling helmets are made from.
We can make EPS formers to the exact shape we want before laminating carbon fibre around them and placing the whole lot in a mould. When heated, the individual beads in the EPS formers swell. Out in the open they'd reach 40 times their original size but constrained by the mould they exert pressure on the inside of the carbon fibre, pushing it into exactly the desired shape with consistent thickness and no wrinkles.
It's not just about the materials: woven carbon filaments by themselves aren't very useful. What turns carbon fibre from loopy sheets to stiff, resilient frames is epoxy resin. The resin binds the layers of carbon fibre together to form a composite structure. Our epoxy blend contains Carbon Nano Tech (CNT) reinforcement in the resin.
These molecular-level cylindrical structures can strengthen a product significantly, but success relies on careful manufacturing. It's easy for the tubes to clump together, leading to inconsistencies. Our careful construction process and technology gives us precise control of the distribution of resin in the carbon layers, ensuring that the nanotubes can do their job – offering a stiffer and more durable frame.