Build Report – Cervelo C5
The Cervélo C5 is a disc brake equipped road bike weighing in at 7.25kg. There is a rethink on some traditional concepts on bike design and construction techniques. Here is the ‘Build Report’ from our test of the C5 in February 2016.
The C5 goes against the conventions Cervélo has built its reputation on. This is not a bike tailored to those wanting to push the limits through aerodynamic gains or lightweight advantages. Instead it prefers its rider to push their boundaries, prompting them to go further with more comfort and stability than was previously possible.
The capability of fitting 38c tyres to the disc brake equipped wheels provides enough temptation for owners to try their hand off-road on trails or single track.
This is an untrodden path for the Canadian company which until now has spent all its energy convincing the road and triathlon market that its bikes are The Fastest.
Aside from a categorical change in direction, the C5 is also the first new model from Cervélo to have a ‘5’ in the title – an indication of the most premium road-specific model.
It may be trivial, but there’s something in the fact that the P, R, S and T frames all started with a ‘2’ or ‘3’ suffixing the letter. Then, as technology has evolved, ‘better’ framesets with higher numbers have been released.
Is this the best ‘C’ series bike we’ll ever see from Cervélo?
The Cervélo C5 was reviewed in #RIDE71 (publishing in February 2016). For the full review, see p.184 of the magazine.
The point of all this is that Cervélo has demonstrated a degree of conformity by introducing the C5 into its road cycling quiver.
Complying with trends is certainly not what Cervélo has traded on in the past but regardless, when I first heard about the C5, I couldn’t wait to try it.
I looked forward to seeing if the fat-tyred sibling of the R5 and S5 had all the hallmarks of a Cervélo despite the obvious differences.
At the time of the review, this bike retailed in Australia for $9,700 – built with a Shimano Dura-Ace mechanical shifting groupset and Rotor cranks.
This may have been an entirely new Cervélo but some innovations will never be altered. The asymmetrical BBright system is employed to increase stiffness — like it has for all this company’s bikes — without a weight penalty.
The bulbous seatstays were found to be effective at ‘compressing’ the rear triangle when encountering large bumps.
It’s nice to see Shimano’s flat-mount RS805 brake calipers in action. At the time of testing, they had been on the market for close to 18 months but few manufacturers have chosen to fit them on stock frames. They performed as well as any other disc caliper tested by RIDE.
Into the workshop… with some hydraulic fluid.
The Cervélo C5 Build Report
– By RIDE Media
Formerly concerned with speed and aerodynamics, the C5 brings Cervélo to those who want to ride in a relaxed and stable position. A number of tech tricks have helped achieve this feel and many of them were picked up during a deconstruction and reassembly of the bike.
Forks, headset and thru-axles
For the first time, Cervélo has not fretted with a low frontal area in the pursuit of cutting-edge aerodynamics and has beefed up the head tube with a 1-1/2” lower bearing tapering into a 1-1/8”. This is nothing special in the modern cycling landscape but it is a new frontier for Cervélo.
(The brand uses 1-3/8” lower headset bearings on the R and S series frames, and 1-1/8” straight steerer tubes on the T4 track frame and the time trial P series bikes.)
A thickened headset should mean greater strength and stability on the road, which is good news for the owner of this bike.
The slack head angle and tall head tube suggests that riders on the hefty side would be drawn to the C5, so the more laterally stiff the bike, the more responsive it will feel for heavier riders.
Another aspect that helps tighten up the front end is the thru-axle that fastens the wheel to the forks.
It seems as though thru-axles will become the convention for disc brake bikes in the future but the sizing of these axles needs to be standardised soon.
Designed for stability over aerodynamics…
Comparing the Focus Izalco Max Disc (which was also on test in #RIDE71) with this Cervélo C5 shows just how close the industry is to finding a ‘standard’ set-up but unfortunately it falls short. Forget the disparate fastening systems (Focus’ R.A.T is cool but it will never be taken up by all brands), the widths of the thru-axles on each of these bikes are different and the method of measuring axle lengths varies from brand to brand.
The thru-axles on the Focus Izalco Max Disc are measured as 100x15mm front, 142x12mm rear.
This Cervélo is measured as 125x12mm front, 170x12mm rear.
In these instances, the hub’s widths are the same, but the axles would appear to be vastly different. Crucially, the Focus and Cervélo take a different fork axle – 15mm on the Focus and 12mm on the Cervélo.
Mountain bike forks use 15mm thru-axles as standard, so one could say that Cervélo is shooting for something a little different which is to be applauded. The only drawback to innovation is that it’s just another thing for retailers, manufacturers and consumers to be wary of when considering new wheels.
The fork itself is a terrific, broad unit with a perfect finish at the axle and brake caliper mount point. It was developed and manufactured in the US at Cervélo’s famous ‘Project California’ lab (the same place where the mouth-watering RCa frames are built) and the quality is obvious.
Bottom brackets have been fine-tuned over the years but Cervélo is happy with its ‘standard’.
Mechanics would be pleased to know that, as these forks are not a descendent of 3T (like most Cervélo forks), so a regular expander plug can be used in the steerer to set the headset bearing tension.
Other Cervélo bikes require something that resembles a steerer star nut to be glued into place with a strong epoxy.
This means that once the steerer tube has been measured, cut and glued, it cannot be easily trimmed. The tall head tube on the C5 should encourage the rider to experiment with handlebar height so this ‘traditional’ expander plug for the carbon steerer is a wonderful alteration to Cervélo’s regular configuration.
The 2016 Cervélo C5 featured a great black, grey and ‘bronze’ finish…
Setting up the disc brakes
These are the first direct-mount brakes RIDE tested and they proved to be as easy as any Shimano system to work with.
Brake hoses had to be routed through the frame without the olive or compression nut in order to fit into the C5’s small frame openings. This meant the brakes had to be installed without any oil and then filled and bled so they could function.
The brakes had to be bled about three times to fill the system with mineral oil devoid of any air bubbles (this is imperative for the brakes to achieve a positive lever throw).
Shimano’s bleed process is very easy to carry out and is almost impossible to get wrong.
A key point with the new direct-mount calipers is to clean-up thoroughly after the bleed before brake pads are reinstalled. Brake pads are extremely porous so if any mineral oil gets on the pads and is not dealt with immediately it could mean an annoying squeal with even the slightest brake application.
After assembling and tuning this bike, a carpark test ride revealed that the rear brake pads were contaminated with something nasty. The squealing didn’t subside after some short, sharp braking so the pads were removed and sanded, and the rotor was sanded.
Thankfully, this silenced the brakes and the bike could be ridden without earplugs and, during the testing period, they stopped perfectly.
The derailleur and rear brake cables enter the frame through the centre of the down tube with the guidance of a split plastic ferrule.
It works well but, when starting from a bare frame, the builder must make sure that no cables cross and get tangled before they are tensioned.
If the cables are being changed individually there should be no problems.
Without any rubber or internal routers it’s difficult to see how the rear brake hose will not rattle around the frame when riding. It will become obvious during a test ride if Cervélo has been lucky or lazy with its brake hose routing.
Cervélo claims that its new bottom bracket cable guide is smoother than it has been in the past but negates this improvement by feeding the cables through plastic cable guides under the BB. These prevent grit and water from encroaching on the steel cables but also make shifting slightly sluggish.
It’s a question of doubling the longevity of gear cables or having a crisp Dura-Ace shift.
The shifting is not bad but other bikes without this sleeve give slightly better gear changes.
For the full review, see your copy of #RIDE71 (volume 01, 2016).
We are getting used to disc brakes but the process of cutting a line, installing olive and barb, then bleeding and centring is still significantly longer (and messier) than fitting a cable-actuated brake.
On the Cervélo, the derailleur cables were easy to route and the headset was a standard Ahead so there were no complaints for the regular features on a bike.
There was not a skerrick of carbon out of place anywhere on the bike and the paint finish was perfect.
The most impressive finish comes on areas that often let road bike manufacturers down.
The carbon entry and exit of the thru-axle is wonderful and the brake caliper mount is flush without errant paint, allowing a flat bed for the brakes.
A slight detractor is that the brake hose and derailleur cables enter the frame quite close together and could get tangled during a cable swap which could cause a couple of headaches.
Apparently Shimano is going to produce series labelled hydraulic levers and calipers (Dura-Ace, Ultegra, 105, etc) but until that happens, these levers are still RS685 which indicates they are Ultegra level rather than Dura-Ace.
The derailleurs are Dura-Ace and the wheelset is excellent so Cervélo finds itself somewhere between a Dura-Ace and Ultegra mechanical rating for its C5.