Wednesday, May 30, 2012

Cervélo S5 review

Cervlo started the aero road bike genre, and they’re still very much at the forefront with the S5. The latest evolution of the species is spectacular in terms of raw aggression and savage speed.

Ride and handling: Incredibly rigid, powerful and fast but at the price of comfort

When it comes to the rear end of the chassis you couldn’t get much sharper-feeling than the Cervlo. The first time we pushed the pedals hard, pulling out from a junction, we almost got left behind as it flung itself forwards with shocking immediacy.

Despite a relatively weighty frame, it’s the same story whatever speed and gradient you press the pedals at. Whatever wattage you can deliver, the S5 will use it to fire you down the road as firmly as if you were pressing your carbon-soled shoes directly onto the Tarmac. Launching out of a corner or leaning on the big chainring as hard as possible up a calf-bursting climb, the Cervlo is like dynamite in terms of its dynamics.

In fact, unless the roadsurface is pretty perfect, you’ll need measured muscle twitch just to keep the tyre sitting on the ground rather than ripping itself out of traction with sheer torque.

Considering the normally rock-solid steering manners of Cervlo bikes, we were surprised by how flighty the front end felt. While the steering angles are nothing untoward and the bars are rock solid, the handling is surprisingly quick and unnervingly flexy.

The tall, skinny head tubeand slim tapered top tubecontrast very obviously withthe brutally stiff back end. Fora start, it means a smoothpedalling rhythm is needed tostop the front end snaking intime with your pedal strokes.This is particularly noticeableif you throw in a crosswind asyou put the power down.

The approximate ratherthan accurate front endtracking is also at odds withthe naturally super-rapiddescending speed of the S5.That means we had someproper held-breath,hammering-heart momentsslotting between potholes orcoaxing through tightcorners in the Dales. It’ssomething you get used to but it definitely favours moreexperienced, less easilyspooked riders, and thetwitchiness is noticeablethrough clip-on tri bars too.

While the slim top tubetakes some sting out of thevibrations when the frontwheel hits stuff, there’s nosuch respite from the roadsurface at the rear. Any jolts orjarring from the rear wheelwallop straight through thesaddle, which again makeskeeping a smooth tempo onrougher road surfacessomething of an art form.

We noticed that althoughthe heart rates and speeds wewere hitting (and holding)due to the bike’s aggressivenature were seriously high,our overall fatigue levels werealso up there, even afterrelatively short sessions.

Frame and equipment: From spec to geometry the S5 is built for purpose

‘Cutting edge’ is the right phrase to use when describing the new S5. The head tube is as slim as the slightly tapered fork will allow. Its height is offset by the shorter than usual fork, which fits flush with a notch in the down tube. The top tube tapers towards the seat mast.

The down tube starts as a deep blade then fattens to shroud the bottle before swelling into a massively deep, box-section, tri bike-stylebottom bracket. The rounded seat tube that curves back round the wheel before heading up vertically to the saddle is another signature Cervlo feature.

The aero seatpost also lets you set up the saddle conventionally or with a run-friendly forward seat angle. Cables all run internally with neat Ultegra Di2 control options and a flush fit cam wedge for the seatpost. The brakes are conventionally mounted on the front of the fork but partially hidden by the rear stays.

Chainstays big enough to be mainframe tubes on most bikes ensure undiluted power delivery, and the short bladed seatstays are shaped for speed, not comfort.

While they’re all shaped essentially the same, there are three grades of S5: we tested the heavyweight ‘basic’version (2,499.99, frame and fork). There’s also a Team version, which saves 100g for another 500, or the S5 VWD, which saves 270g if you fork out another 1,500 on top.

Whichever model you choose, the S5 will come as a frame, fork and seatpost chassis that you build up, but the build here is worth commenting on. The ultra smooth, seamlessly slick Ultegra Di2 electric shifting suits the urgency of the bike superbly. Well-placed wire ports make it a neat installation, although the massive front mech isn’t the most aero shape.

The Pro Vibe Carbon bar and stem are brutally stiff for locking your shoulders into and letting rip on sprints or climbs, which suits the bike’s character. The Dura-Ace wheels are smooth but slightly heavy and noisy when combined with the box-section frame. A more forgiving saddle than the riveted San Marco could offset the stiffness of the bike, though.

This article was originally published in Triathlon Plus magazine, available on Zinio.

By: Road Bikes & Gear

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