Additive Manufacturing and Amateur Triathlon Competitors: Developing an Affordable Carbon Fiber Bicycle
In this article we meet Tuomas and Kimi, two amateur bike enthusiasts, who are also our friends and colleagues, with a simple aim: to build an affordable custom composite bike to compete in triathlon events. They pooled their knowledge of materials science and manufacturing in order to design and build themselves a triathlon carbon fiber bicycle.
Custom-made carbon composite bicycles too costly for amateur cyclists
There are several bespoke high-tech carbon composites bicycles out there, but they are all very expensive items for amateur competitors. “We looked at means of reducing this cost from both a design and a manufacturing approach”, explains Kimi.
Using standard composite parts to bring down costs
“Our concept uses conventional carbon fiber composite tubes. The tube stiffness contributes to the overall ride performance of the bike. It’s down to rider preference: a trade-off between good power transfer and comfort”, explains Tuomas.
This largely avoids the need for the expensive complex geometry molds to make aerodynamic tube sections, but it doesn’t eliminate it.
“The key points remain those where the various frame elements come together: known as the head tube, bottom bracket shell and, for this study, the seat cluster. It’s where the composite tubes are bonded together, so an important component regarding load-bearing and durability”.
Optimising key composite components
“For the proof of concept study, we chose a wet lay-up of carbon fabric to help it drape over and around the core”, explains Kimi, “In the next development stage, we will take a closer look at optimising the engineering properties of the composite. This can be done fairly easily using ESAComp, the software tool from Componeering Inc”.
“We are also equipped with Altair software, including solidThinking Inspire, used for topology optimization of complete frames and some metal parts, plus HyperMesh for basic finite element analysis (FEA)”.
3D printed molds – a low cost option to make complex composite parts
“To manufacture the seat cluster component, we investigated 3D printing as a method of making a two-part mold with an internal removable core”.
“If mould materials were too stiff, then the mould could crack on closing, whereas too flexible and it wrinkled, so the part didn’t keep the required shape”.
The core design includes internal features as supports during moulding, but are also necessary for the printing process – can’t print onto fresh air! Here, cores were removed mechanically.
Frame assembly – a one-step bonding process
A jig ensured all parts came together correctly and retained the geometry throughout the 7 day cure.
“Our first one got a traditional “Finnish post cure” = 4 hrs in the sauna!”
Some preliminary performance stats….
“The bike frame shown at JEC World 2016 weighs 1.4 kg. We are not focused solely on weight because ride characteristics and structural reliability – along with price – play an important role, too”, Kimi explains, “Using more expensive bolt-on components can reduce overall weight, but it increases price”.
2016 Finntriathlon events – the ultimate test schedule!
Tuomas is ready to put the ideas2cycles bike through its paces at triathlon races (sprint and Olympic distances) in Finland during 2016.
“We are honing our design specifically for these races! It’ll look more like a road bicycles, using road handlebar and shifters, because the geometry of the current design is better suited for this purpose”, Tuomas explains.
And, talking of price ……
“With this frame, we can do a bespoke build to meet customer requirements starting from about 4000 EUR (4600 US $)”, says Kimi, “making high-tech, personalised performance affordable”.
Componeering would like to thank Kimi and Tuomas for their assistance in compiling this article and their permission to reproduce photographs from ideas2cycles.
ideas2cycles was founded in 2010 by students from Aalto University, Finland
You can also “Follow Dragi” on his quest to ride 12,500 miles this year on a new bicycle developed with the help of Altair!