The Cervelo P5X: Three Years in the Making Part 3

After more than a decade spent fitting and coaching some of the world’s top athletes — Ironman World Champions Craig Alexander, Miranda Carfrae and Frederik Van Lierde, to name a few — I can say with certainty that a proper bike fit is the biggest performance upgrade you can make to achieve your personal best.

I joined the P5X project as the Director of Human-Bike Interaction in 2015, two years after I started advising Cervélo’s engineering team on everything from range of adjustment to the needs of my high-performance clients. I fit Cervélo’s pro athletes on the new bike, took part in wind-tunnel testing to validate the best rider position and, most importantly, helped develop a Bike Size and Setup Calculator on the P5X configurator page that anyone can use to find their most appropriate bike size. Speed = Comfort + Power + Aerodynamics

When an athlete purchases a tri bike, they are buying speed. Roughly 80 per cent of a rider’s energy output is used to overcome resistive forces, primarily aerodynamic drag. A tri bike allows an athlete to obtain a position that minimizes drag, and maintaining this position depends on one factor above all else: Comfort.

An athlete must be able to sustain the time-trial position for the duration of their event. If they aren’t comfortable on the bike, aero will be compromised and speed will be affected, not to mention the adverse effect it could have on the run. Getting the perfect fit is about being able to adapt and fine-tune every single touch point.

An athlete’s contact points should be positioned in a manner to allow the rider to pedal within accepted biomechanical norms without restriction. A proper bike fit will allow an athlete to freely apply force to the pedals ensuring power is not compromised. This is why power comes back to fit, too.

The third factor in our speed equation involves aerodynamics; in other words, optimizing the frontal surface area and shape of the rider and their equipment to minimize aero drag. At this point we are only looking at the range of adjustment that enables subtle position or posture changes, since we already know that the P5X is the fastest Cervélo tri bike ever made.


The unprecedented micro- and macro-adjustability of the P5X allows every athlete to find their perfect position quickly and easily. Its wide front-end fit range features 112mm of sliding stack with up to 12 degrees of tilt and 91mm of reach adjustability, as well as a flippable base bar. With other tri bikes, making smaller changes in position is cumbersome, and fitters have little margin for error. With the P5X, micro-adjustments can be made in seconds with just a few bolt turns. Combined with the ultra-low standover height, the four new frame sizes — S, M, L and XL — simplify both fit and sizing. This range allows athletes to personalize their positions based on race distance, individual morphologies and positioning needs.

In the end, I’m proud of what I see as the greatest achievement of the P5X: The ease with which athletes, shops, and fitters can make subtle adjustments to set up the bike for speed.


The Cervélo team wanted to clear up any confusion over which size suits you best. Superbikes don’t feature traditional stems or handlebars, which could make sizing difficult if you’re unfamiliar with using arm-pad stack and reach. Our goal was to take the guesswork out of this. With the tool on the P5X microsite, athletes, retailers and fitters need only enter stack (Y) and reach (X) coordinates, as well as saddle height, and the appropriate bike size and adjustments will be revealed.