If you are a fan of Buckminster Fuller, you are no doubt familiar with the principle of Tensegrity (or tensional integrity), which is “based on the use of isolated components in compression inside a net of continuous tension, in such a way that the compressed members (usually bars or struts) do not touch each other and the prestressed tensioned members (usually cables or tendons) delineate the system spatially.”
I have mentioned Tensegrity bicycles in the past, and any discussion of bike frame designs with tensioned cables reminds me of the Slingshot designs of the 80’s and 90’s. The basic idea goes back many years before that though (as you will see at the end of this post).
Recently, the folks at Clandestine Design Group, an Australian product design firm, came up with a couple of new designs for a tension bicycle that they call the CrossBow. The idea came from Brisbane’s new Kulripa Bridge. “The Clandestine crew where inspired by its architectural use of construction elements in tension rather than compression.”
Neil Davidson, Clandestine Design Director, explains the impromptu project further:
“Always looking for new ways to design things with wheels we immediately wondered if bicycle frames had ever explored this concept. We thought that advances in composite fibre and fibre filaments could create road bike frames that would be feather light and structurally strong.
Research shed light on two things, the first was that modern composite filaments millimeters in diameter are cable of holding tones of mass in tension and the second is that if a one human can think of it, then so can another – we found out that the concept is not new. Check out the dapper looking gent from the 1920’s and his tension suspension frame.
Regardless and still inspired we put stylus to screen and sketched out two great looking mens’ road bike frames that use the concept of carbon fibre frames held in tension by filament wire or cable. For now we are running with the internal project name of Crossbow. You will note the second sketch explores a electric assist crank set hub drive concept.”