Carbon fiber meets simulation in ultralight bike frame

In this case study, Composites World editor, Jeff Sloan, tells the story of Rolo Bikes, a company that wanted to design a bicycle frame with carbon fiber in mind, and it wanted to test it in the virtual world.

As bicycle materials and technology have improved, bicycle design has matured. Today, it revolves primarily around two factors: Weight reduction and rider comfort/ergonomics. The former has reached its zenith in all-carbon fiber composite bike frames, for which riders pay a high premium — similar to that paid for carbon fiber use in high-end automobiles.

Carbon fiber bike frame design and manufacture have largely mirrored that employed for steel and aluminum: a series of mass-produced tubes that are subsequently bonded together (aka, “black aluminum”). The bike manufacturer is rare who has developed a single-piece, monocoque carbon fiber frame. Until Rolo Bikes (Luxembourg; Stockholm, Sweden) met Altair Engineering Inc. (Troy, MI, US), it was virtually impossible to find a bike manufacturer who has designed, developed and manufactured such a frame optimized specifically to use carbon fiber composites.

Rolo wanted to design a bike frame that optimizes rider comfort and pedaling efficiency, applying carbon fiber in a way that maximizes material application while minimizing weight. This would require a holistic, back-to-basics design assessment. They began by looking at the relationship between the three human contact points on a bike: The saddle, handle bars and pedals.  With their data, Rolo  developed its first carbon fiber monocoque bike frame, designed in Dassault Systèmes’ SolidWorks.

They were not yet done. The lightest bikes in the world have frames of less than 700g, and Rolo had to be able to compete at that level.  Using Altair’s design expertise, virtual test structure was created that emulates the type used in Zedler Institute tests for strength and stiffness requirements. Into this went a finite element model of the Rolo frame.

Rolo Bikes/Altair Ultralight Bike Frame Design Illustration

Rolo Bikes/Altair Ultralight Bike Frame Design Results (Credit: Karl Reque)

With a new, optimized design and a new playbook 
in hand, Rolo then went to work proving that 
the virtual results could be replicated in the 
real world.  Based on what they know, they think they would be pretty confident going straight from simulation right to production tooling with only minor modifications. With the optimized design and more efficient manufacturing process that results, Rolo hopes to drive down the overall cost.

>Read more by Jeff Sloan, Composites World, 4/8/16