Another ‘P’ from Cervélo? The latest blockbusting time trial bike from the self-styled bike brains of Canada appeared last year unexpectedly hot on the heels of its predecessor.
The previous flagship model, the P4, was launched at Interbike ready for the 2009 season but by 2012 had already been superseded. What happened is that Cervélo beefed up its computational fluid dynamics capability at its Toronto HQ and, whereas the P4 was designed in the wind tunnel using trial and error, the P5 was entirely developed in CFD and ‘validated’ in the wind tunnel.
For the P4’s development, Cervélo constructed a mannequin made of foam based on David Zabriskie. For the P5, Foam Dave was left slumped in the corner of the wind tunnel like a marionette the children got bored with.
Cervélo saw an opportunity to make a faster bike using new technology; what also drove the decision to start work on a new flagship TT frame so soon was slightly critical feedback from P4 riders and mechanics. The rear brake, which was sited behind the bottom bracket – the P4 was one of the first of the new-generation TT frames to put it there – was tricky to set up and adjust. Cervélo couldn’t have known that wider-rimmed racing wheels were about to break through, and those caused problems with the custom-designed caliper.
The other thing was that the bottle that filled in the bottom of the main triangle for aerodynamic purposes (non-UCI only) was not very easy to use.
So the P5 was engineered to smooth out both the P4’s niggles and its aerodynamics – Cervélo says the P5 is 6-11 watts quicker than the other so-called superbikes, saving roughly 24-44 seconds over 40km. If true, that’s enough to make it a game-changer.
So what’s new? Well, with the UCI clamping down on very long aerodynamic ‘tails’ on teardrop-shaped tubes and components used in time trialling equipment, Cervélo has interpreted the rules to get around the 3:1 aspect ratio regulation. Frame gussets – usually strengthening plates reinforcing the tube junctures – are perfectly legal and can be any shape. So Cervélo created a gusset that works as a 3:1 aerofoil tail behind the 3:1 head tube, giving a much longer combined ‘chord’ (the distance from leading edge to trailing edge) than would normally be allowed. It’s the same arrangement at the seat tube/top tube junction zone – there’s another very long aerofoil section. In basic terms, the longer the chord, the lower the drag.
However, there’s more to creating an aerodynamic bike than putting together a bundle of aerofoils. The moving parts (wheels and rider’s legs) have to be factored in, and these can have a profound effect on the overall aerodynamics. Cervélo says a riderless P4 is actually faster than a riderless P5 – but what happens in the real world, where bikes need riders, is the key concern. There, the P5 prevails.
At this point it’s worth noting that for £1,000 more, you can have the P5-6, which is the non-UCI version intended for triathlon. Cervélo has let aspect ratio run riot, with a cowled hydraulic brake caliper integrated into the front fork increasing the front-end chord length yet further. This bike is legal in British time trials run under CTT rules and regs, but not for the BTTC national time trial championships.
Time trial frames like this, with enormous tubes, lend themselves perfectly to electronic groupsets, as the battery pack can be completely concealed. The Di2 P5 has its battery in the space above the bottom bracket, accessed via a plate in the rear of the seat tube. In the mechanical version this space becomes a handy cubby-hole for storing a spare tub, phone, car keys or whatever you want to stash in there.
Big tubes also mean a stiff frame, and to make sure of it, Cervélo has used its own BBright bottom bracket standard, which adds 11mm to the width of a standard BB shell without increasing Q factor. There’s a 30mm-wide axle like BB30’s, but the left-hand aluminium cup is replaced by extra asymmetric shell width. Cervélo claims a 20 per cent stiffness increase over the P4’s bottom bracket.
Test-race of truth
It’s both a blessing and a curse to be asked to test a bike like this. If you can get it to fit you well enough to compete on, a WorldTour-level time trial bike with a top-line spec is guaranteed to be faster than your own idiosyncratic TT bike. But the problem is you have to give it back. The other difficulty is trying to articulate exactly what it feels like to ride a WorldTour-level time trial bike with a top-line spec.
As far as the position on the bike is concerned, the P5 is slightly easier on the spine than the P3 and P4, which will appeal to triathletes and less supple time triallists. Cervélo says it fits a wider range of positions, but that’s with the P5-specific bar that Cervélo developed with 3T rather than the Pro Missile bar here – which gave a very aggressive front end with not a great deal of adjustment possible for stack height/armrest width.
We don’t have the facilities here to verify Cervélo’s multiple claims for this bike, but I did have a club TT and fairly mediocre early-season form at my disposal. I would estimate I was about 30 seconds faster than I ought to have been on that particular course at that time of year, and the amount of time I was ahead of the other riders backed this up. In the following events, where I was back on my own bike, the old order was restored – no more surprise fast times or wins.
Riding a TT hurts if you're doing it properly, and my only criticism is that the P5 does nothing to alleviate that pain. With an upright, radically teardrop-profiled seatpost, the only detectable ?give' comes from the saddle padding and the tyres. A sporting 50 might be quite uncomfortable. Still, the P5 is all about all-out speed and, whatever your ability level, it will definitely make you go faster. It just depends how much of a kicking your rear-end - and your wallet - can take.