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The jagged cobbles of Paris-Roubaix have inspired some very creative thinking among frame manufacturers over the years. In the early 1990s, Greg LeMond took to the cobbles with newly conceived RockShox front fork suspension. A few years later, in 1994, Bianchi took things further with a full-suspension frame. A decade after that Trek developed the SPA rear suspension system, putting a shock absorber in the wishbone at the top of the seatstays, an idea which lasted for a season or two. Then in 2012, Trek released the Domane, with the IsoSpeed decoupler, a pivot system that means that the seat tube can move independently of the rest of the frame.
So far, the Domane is the only survivor in the battle for a viable road bike suspension system (of sorts) – that is, unless the Pinarello Dogma K8-S can change the game. Pinarello’s solution to the severity of the cobbles is reminiscent of Trek’s original SPA system, as well as the older YBB system from titanium brand Moots, but the engineering behind it suggests there has been plenty of original thinking along the way.
‘This isn’t the first true suspension system available on a road bike, but it is the first UCI approved,’ says Massimo Poloniato, R&D engineer at Pinarello. ‘We didn’t collaborate with anyone from the mountain bike world. We collaborated with Jaguar Land Rover and its experts in suspension and vibration damping.’
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Pinarello’s DSS 1.0 suspension unit includes a rubbery elastomer within a cylindrical sleeve at the top of the seatstays that can pivot at the point where it joins the seat tube. A few quick attempts at deflection in the Cyclist office showed that the suspension unit does allow considerable movement – easily deforming 5-10mm simply by shoving down hard on the saddle. That’s while using the maximum preload setting, which can be adjusted using a basic lock ring tool to lessen or increase the level of suspension. Pinarello claims that the frame has compliance to allow 9mm of vertical movement at the rear wheel.
The position of the suspension may intrigue some, because historically some suspension systems for road bikes have focused on the front of the bike rather than the back. ‘Usually on rough terrain pro riders move their weight onto the rear wheel, unloading the front wheel,’ Poloniato says. ‘Following this consideration we chose to work on the rear of the bike – in this way we could maintain the Dogma’s handling quality.’
The front end of the frame has also been adjusted, though, but only with more conventional methods. ‘On the front triangle, following the experience with the old Dogma, we decided to revise the head tube angle and the fork rake,’ says Poloniato.
The K8-S was not conceived solely for the ruthless pavé of the Paris-Roubaix. Rather, the bike has a broader remit as Pinarello’s comfort endurance bike for all terrains – akin to the Trek Domane or Specialized Roubaix. As such, Pinarello has tried to keep the overall weight of the K8-S down, including the DSS 1.0 unit.
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‘The weight of the raw [unpainted] frame in medium size with the suspension is 990g. We consider that this bike is not intended only for the pavé but offers more comfort on all surfaces, including standard roads,’ Poloniato says. Cyclist weighed the full bike (size 54) at 7.42kg, and we reckon that with a change of wheels there’s every reason to believe it could drop to the UCI minimum weight of 6.8kg.
Given Pinarello’s recent leaning towards increasingly stiff fibres, the K8-S seems to be a viable solution to the inevitable discomfort that rigidity can bring. ‘The current road bikes are getting stiffer and stiffer and the result is a lack of comfort,’ Poloniato confirms. But the design has not been as simple as just inserting a suspension system into a ready-made Dogma F8.
The carbon lay-up has been reconceived to allow for the new flex in the system, something that took a full year of development using the F8 as the starting point. ‘The chainstays must keep the same lateral stiffness of our current bike to preserve the power transfer and in the meantime they must allow a vertical displacement to make the suspension work properly,’ Poloniato says. ‘The tube shapes have changed, especially at the rear. We also revised the carbon lay-up to get that 9mm of travel on rear wheel safely.’
With cobbles on the menu at this year’s Tour de France, Chris Froome will no doubt be thankful for anything that can get him past Stage 4 unscathed, but only time will tell if the Pinarello Dogma K8-S will pave the way for a new generation of road bikes with suspension, or become just another blip on the timeline of tried-and-rejected solutions to cobble comfort.