Most companies use Finite Element Analysis or FEA to analyze the stresses that a potential bike frame design will go through. One popular software suite called Creo made by PTC (formerly named Pro/Engineer) allows engineers to observe areas on frames that correspond directly to test lab failures. In other words they can predict what junctions or surfaces may fail before producing a test mold/frame and putting it through a mechanical test jig. FEA software utilizes a complex network of individual nodes that together create a mesh (grid). The mesh represents the material (carbon, aluminum, etc.) and the structural properties, which define how the structure made of this material will react to specific load conditions.
The image below shows an example of high stress regions in red, most likely caused by stress via the fork.
Consumers many times over hear about how carbon fiber is X many times stronger than aluminum, steel, or titanium and often wonder why they still see damaged or destoryed carbon frames. Well the answer to that question is that carbon is meant to be very strong in fact much stronger than the aforementioned materials in the axis or planes of movement that it was designed to be stressed in (that is riding) so in a race crash scenario you might have a competitor’s knee crack a seat stay on a carbon bike where it might have just caused a dent on an Aluminum frame.
The calculations made on FEA software are very intricate and don’t factor in the nature of the rider (major mass) riding the bike. The frame will behave differently when stressed alone than with a rider mounted. Rest assured manufacturers test these frames on screen then put real frames through rigorous testing machines such as the one pictured here:
Many of you no doubt have heard “vertically compliant and laterally stiff” and might find it’s overuse condescending as a savvy consumer. In our next article we’ll discuss just what manufacturers are doing to support that claim.