Stiffer is better! Aero is everything! The bike world sure does love its bold statements. But actual bicycle riding is far more nuanced. So when you’re told over and over that frame flex is bad and stiffness is the most important aspect of frame design, you can take heart knowing frame flex isn’t necessarily a bad thing in certain contexts.
Graham Shrive would know. As an engineer for Factor Bikes, and Cervelo Bikes before that, Shrive has helped design some of the fastest bikes in the pro peloton. And Shrive certainly understands that frame flex can be a detriment to the rider, but it can also be of great use in certain situations.
Frame design comes down to a lot of moving factors, none of which you should actually be thinking about while you’re riding. Instead, the frame flex should be built into the overall design so that you feel its effectiveness. Cornering, Shrive says, is a great opportunity to understand the value of stiffness and flex. That’s where you can feel the wheels tracking in a plane, or wandering off course due to torsional forces playing on the frame, fork, and wheels.
Sprinters and climbers, unsurprisingly, have different frame flex and stiffness needs. Shrive has worked with some of the biggest names in the sport, from Chris Froome to Mark Cavendish. Rider feedback often indicates where frame flex needs to be tailored or eliminated altogether; it’s up to Shrive and engineers like him to interpret that rider feedback — which is rarely, if ever, given in engineering terms — and turn it into improved ride quality.
Shrive also gives us an understanding of how and where frame flex occurs. As you might imagine, a frame flexes in different areas along different axes, so it’s important for engineers to understand not only where the frame flex occurs, but also how to either eliminate it or use it to the frame’s advantage.
Materials like carbon fibers and resins come into play here. While adding carbon to certain areas of the frame can eliminate or reduce frame flex, there are now other more efficient ways to do it. Different carbon fibers, for example, can help an engineer tailor stiffness without adding extra layers and bulk. Shrive gives us a basic rundown of how that works in this week’s episode.
As always, if you have questions about this episode of the VeloNews Tech Podcast, or suggestions for topics you’d like us to cover on a future episode, feel free to reach out to tech editor Dan Cavallari via email, Instagram, or Twitter.