Triathlon events are not governed by the UCI so they are not restricted by the same rules that time trial riders are, meaning that triathlon bikes are free to push the limits and capitalise on developments in technology. The results are wonderfully space-age bikes like the P5X.


Cervélo claims to have the most aerodynamic bike on the market. Unfortunately, we left our portable wind tunnel at the office on the day of the shoot, so we'll just have to believe them. James explained that the crosswind impact is much better than the older P5 as there is less frame material higher up and towards the back of the bike where you have less control compared to the front wheel.

Chatting to James, it is clear that he is a bit of a bike geek and likely the reason that Cervélo and ENVE have had him involved in the development of their products. James's biggest push was tubeless wheels and, for that reason, disk brakes as well. With the P5X and ENVE SES 7.8 wheels, he's gotten just what he wanted.


Moving away from rim brakes makes building a wheel much simpler. There are no more concerns about a braking surface and the resulting heat dissipation. Without these factors, ENVE has been able to build a better and more reliable aerodynamic tubeless rim. The brakes on the bike are TRP HY/RD. They feature a hydraulic system on the brake that is mechanically operated, allowing compatibility with existing road brake levers.


With the wheels, I don’t chop and change too much. The 7.8’s are shallow enough to ride in most crosswinds, probably near a disk wheel in stiffness and light enough for climbing. ENVE are adamant that their wheels are as good as a disk wheel. James Cunnama


This P5X is set up exactly as it was when James raced at Ironman World Championships in October. Having been unveiled just before the event in Kona, the bike was brand new and it was the first time he had raced on it. Having to keep the bike under wraps meant that he did not have much training time on the bike either. Cervélo, however, were meticulous with mimicking the fit from his previous P5, making the transition seamless.

Although the retail P5X is sold with the wireless SRAM Red eTap drive train, James had some compatibility issues with some of his other components and decided to race on Shimano DuraAce Di2 drive parts instead.


The DuraAce rear derailleur features a CeramicSpeed cage to fit the brand's oversized 17-tooth pulley wheels which claim to reduce friction and save some precious watts. James uses a Rotor 2INPower crankset to measure his power through both crank arms with Rotor's osymetric Qring chainrings. He admits that it is hard to judge the impact that oval rings bring but after fitting them to his bike, he won his next four races including his first Ironman win, so he is sticking to them. The finishing touch on race day is a CeramicSpeed UFO racing chain that is designed to be ridden for only 320 kilometres, but offers superior efficiency.


The P5X may be a no holds barred professional level racing bike but Cervélo did not feel this meant that they needed to sacrifice practicality for pros and amateurs.




The aero bars are fully adjustable to help riders get that perfect position. The bars also completely disassemble with the loosening of a few bolts. They can also be removed to make the bike flat for easy transportation. The P5X comes with its own travel bike bag to make this process even simpler.




Cervélo also looked closely at what triathletes of all levels carry during races and where they prefer to have it on their bikes. The result was space for a bottle on the handlebars, on the seatpost, and within the front triangle. The seatpost mount is specifically designed to keep the bottle as close to the rear of the bike as possible but still cater for varying size bottles and cages.



Spares are stored in compartments within the frame included a removable plastic box in the front triangle (as fitted on James's bike). There is also a bag attachment on the top tube where the rider can store nutrition, and there is even a little separator to keep tablets from getting lost.


Full Specification:

  • FrameCervelo P5X 56cm
  • ForkIntegrated P5X (by Cervelo)
  • Rims (Front/Rear)ENVE SES 7.8 disc
  • Hubs (Front/Rear)DT240
  • Tyres (Front/Rear)Schwalbe Pro One Tubeless 25mm
  • HandlebarsIntegrated P5X Cervelo
  • StemIntegrated P5X Cervelo
  • BrakesetTRP HYRD Mechanical/Hydraulic
  • ShiftersShimano DuraAce Di2
  • Front DerailleurShimano DuraAce Di2
  • Rear derailleurShimano DuraAce Di2
  • CassetteShimano DuraAce Di2 11-25T
  • CranksetRotor 2INPower, 170mm
  • ChainringsRotor Qings 54-39T
  • ChainCeramic Speed UFO (racing)
  • Bottom BracketCeramic Speed Pressfit BB
  • PedalsShimano DuraAce SPD
  • SeatpostIntegrated P5X
  • SaddleCobb Plus
  • Bike ComputerGarmin 510
  • Water bottles/cagesX-lab (Torpedo, Gorilla, Sidekick)
  • Computer and PowerGarmin 510 + Rotor 2INPower