Tour de France and bicycles: a showcase for composites
I’m sure a lot of you are watching the current edition of the Tour de France bicycle race, as am I. The spectacle of human endeavor, together with the expert commentary (yes, Bobke), makes for great sports drama. A big part of the Tour, of course, involves the competitors’ bicycles, all made with lightweight carbon fiber composites. That said, since 2000 the Union Cycliste Internationale (UCI, Aigle, Switzerland) has imposed the 6.8 kilo rule, requiring that no bike can weigh less than 6.8 kg, or about 15 lbs, to prevent unsafe frames that are too light. Of course, any bike manufacturer can produce a bike of a lower weight through design and good material selection, but the rule stands — in fact, it’s rumored that team mechanics sometimes must add weights to the frames to meet that race weight requirement.
That put me in mind of the many articles and News items CompositesWorld has published over the years about composite bikes and the design efforts and complex materials that go into them. I’ve compiled a list of most of these, from the oldest to the most recent.
This story by Donna Dawson covered the Trek bicycle used by Lance Armstrong in his sixth victory: https://www.compositesworld.com/articles/at-the-top-and-still-climbing
Another Donna Dawson story covers an “open-truss” frame design to reduce frame weight: https://www.compositesworld.com/articles/new-twist-in-cycling-a-truss-bikers-can-trust
This 2010 article about a mountain bike suspension was written by contributor Mike LeGault: https://www.compositesworld.com/articles/in-search-of-a-better-ride
I wrote this story in 2011 about Vroomen White Design’s Project California research and development facility, the wholly owned engineering group of Cervélo (Toronto, Ontario, Canada), which designed the lightest bicycle frame at that time, at 1.5 lbs.: https://www.compositesworld.com/articles/designing-bicyclings-lightest-pro-racing-frame
Chomarat (Le Cheylard, France) and Dr. Stephen Tsai discussed in 2012 how they developed unbalanced, shallow-angle laminates using new, very thin biaxial fabrics to replace “black aluminum” and simplify layup for a bicycle application: https://www.compositesworld.com/articles/bi-angle-fabrics-find-first-commercial-application
Ginger Gardiner wrote in 2012 about Grenchen, Switzerland-based Bicycle Manufacturing Co. (BMC) and their decision to braid the carbon fiber tubes for its impec racing bike frame, and how the complex tube designs and shapes prompted the use of radial braiding technology from August Herzog Maschinenfabrik GmbH & Co. KG (Oldenburg, Germany): https://www.compositesworld.com/articles/next-generation-braiding-for-next-gen-bike
Jeff Sloan wrote, in 2016, about Rolo Bikes (Luxembourg; Stockholm, Sweden) and Altair Engineering Inc. (Troy, MI, US), and their optimization of a bicycle that improved ply placement and reduced weight by 14%: https://www.compositesworld.com/articles/carbon-fiber-meets-simulation-in-ultralight-bike-frame
And, there might be good reason for that UCI minimum frame weight rule of 6.8 kg, mentioned above. Dr. Scott Beckwith, principal of BTG Composites (Taylorsville, UT, US), offered a review at CAMX 2015 (Oct. 26-29, Dallas, TX, US) of his analysis of evidence in several product liability cases that involved carbon fiber bicycle forks gone wrong: https://www.compositesworld.com/articles/designmanufacturing-flaws-will-the-avoidable-be-avoided-in-future
Fibers used to reinforce composites are supplied directly by fiber manufacturers and indirectly by converters in a number of different forms, which vary depending on the application. Here's a guide to what's available.
All signs point to increasing demand from many market sectors. Will capacity keep pace?
The matrix binds the fiber reinforcement, gives the composite component its shape and determines its surface quality. A composite matrix may be a polymer, ceramic, metal or carbon. Here’s a guide to selection.