Tuesday, April 1, 2008

Carbon Nano-Tube Bicycle Technology


Just when you're wondering which frontier the bicycle industry will push open next, SWISS bicycle maker BMC produced the world's first carbon nanotube (CNT) bike, a material that is now considered the strongest and stiffest material on the planet (..and I thought it was Boron Tri-Nitride) in terms of tensile strength and Young's modulus (elasticity). To improve toughness, the tubing is made in a proprietary process by adding a mixture of fine carbon nanotubes to the carbon-resin matrix. All the specific manufacturing related stuff is anyone's guess.

If this bike were to be tested for strength to weight ratio, the figure would destroy the scales.

Strength/Density Compared [Easton]

A summary of the design from BMC's website :

Throughout, we avoid using the traditional carbon optic. Using only carefully aligned unidirectional fibers makes for even more accurately defined rigidity distribution.

The Carbon Nano Tube Composite developed by Easton achieves unprecedented material values by the admixture of microscopically small carbon tubes.

Integrated Skeleton Concept permits good force distribution near the nodal points by using carefully selected reinforcing elements. Each tube transition can be perfectly adapted to the flow of forces.

You can recognize them from the dropouts. Pro Machine frame with seamlessly integrated carbon dropouts. The only metal component on the whole frame is the thread on the bottom bracket.

The material was developed for frame tubing by the bicycle division of Easton Sports.

Carbon Nanotubes are a highly specialized area of material science research and people in the industry are just beginning to discover the properties and applications of the material.

What it is [Source]

The discovery of nanotubes remains a contentious issue, especially because several scientists involved in the research could be likely candidates for the Nobel Prize [Wikipedia].

A strand of CNT under a scanning electron microscope [Source]

How CNT Will Make A Difference [Easton]

When I look at this technology, I'm NOT thinking in terms of simple tensile strength or stiffness values. Those may be way high compared to traditional materials. There is more to be considered, as in application specific questions - How will a bicycle tube made of this stuff compare to a conventional carbon fiber tube in terms of high and low cycle fatigue strength? What is the strength of the joints? Etc... etc.. If there are only marginal improvements in these properties, I'll be looking to save my pockets.

For what people are saying about this material and considering the huge costs in producing it, I expect it to diminish and virtually eliminate all those catastrophic carbon failures we've been seeing around us for a while now. That much will be good, since I'm nervous about showing the UCI a sub 15 pound bike. I don't want to mess around with them. Too much bike related fatigue to deal with already...

Sigh...until some sensible dynamic test results come out, we're going to be stuck with ridiculously priced bicycles or complete show material.


Anonymous said...

Please note that while carbon nanotubes have ultra properties, bikes (or anything for that matter) are NOT made entirely from nanotubes. As Easton stated: carbon nanotubes reinforce the epoxy matrix. The epoxy matrix only makes up about 30% of the bikes weight, so a large increase in strength/modulus in the epoxy matrix will not increase the bikes strength/modulus by the same amount. In addition to there only being about 30% epoxy matrix, the carbon nanotubes occupy only 3-7% of the resin (not a lot of nanotubes).
Carbon nanotubes show enormous potential for structural properties, but it will be a number of years before these ultra properties trickle down from laboratories to your bike rack.
Great article, keep up the pollination!

Anonymous said...

should have saved this one for april fools cause its a joke on the consumer. the change in finished properties from the nanotubes is extremely small. nanotubes have extremely high strength that is a product of their geometry but have currently not been developed to be useful for anything other than sounding cool. the easton carbon is high quality but the nanotubes do nothing other than allow them to charge more. the aerospace industry uses thermoplastic toughened epoxy to provide better damage tolerance but doesnt waste their time with nanotubes cause they care about performance not sounding cool.

Anonymous said...

Interesting info. A glaring omission on the strength to weight ratio graphic was titanium as a test material.