Building the best bike for the cobbles of Roubaix

I’d never seen the Roubaix pave before hitting Arenberg in the wet on 25mm clinchers last October. The experience was both terrifying and humbling as I’d always fancied a riding Roubaix, right up until the moment I realised I could never have ridden Roubaix. I decided there and then I needed to find a tech solution to my cobbled inferiority and set about building the best bike for Paris Roubaix.

Course demands

The flattest and fastest of all the monuments, Paris-Roubaix looks easy on paper. That smooth paper, though, hides the brutality of the rough cobbled sectors which, as we all know, define the race. Remove the cobbles from Paris-Roubaix and the race almost certainly ends in a bunch sprint every time. But with the cobbles in place, few races are as attritional or end with the same time gaps, crashes, and riders outside the time cut.

Traditional solution

Clearly, the cobbles are the focal point when optimising a bike for Roubaix, with improved comfort and stability the priority for the pave sectors. For decades Roubaix has been the tech highlight of the season as teams and riders broke out all manner of tech interventions in a bid to smoothen the ride north from near Paris.

The second Sunday in April provided a day in the sun for double-wrap bar tape, “wider tyres”, 32 spoke box-section tubular wheels with tied and soldered spokes, cantilever brakes, suspension forks, and cross-top brake levers. Interestingly, almost all those tech solutions have now disappeared, and even the 28mm tyres once considered wide are now in the shadow of their bigger 30 and 32mm siblings. Modern Roubaix tech is becoming less exciting by the year as we increasingly see riders line up for the start on bikes almost identical to those which they use for every other race.

We miss those days of Roubaix tech madness and believe there are still some tricks and tech available today that could make a rider faster over the cobbles. Free from team sponsor obligations and traditional thinking, we set about building the best bike for the cobbles of Roubaix.

Frame

The frame is the basis of any build and so perhaps the most crucial element. Pro teams at Roubaix often have one or two frames to choose from and make the bulk of their cobble conquering tech adaptions to the components mounted to the frame. We had the luxury of choosing any frame and as such could ensure both a solid foundation for a Roubaix build and compatibility with other modifications we had planned. Frame compliance, tyre clearance, handling, stability, and a hint of aero were top of the list of priorities. The Trek Domane SLR promises all of these and throws in a double serving of Trek’s ride smoothening IsoSpeed technology.

With more than ample tyre clearance, at least some aero profiling plus the adjustable and damped top tube IsoSpeed for customisable compliance, the Domane SLR ticks the Roubaix frame of the boxes on paper. Better yet, Lizzie Deignan won the Paris-Roubaix Femmes last October on the same frame and CyclingTips global tech editor, James Huang, described the Domane SLR as a “seriously smooth-riding machine”.

Of course, the current worst kept secret in World Tour racing is Trek’s forthcoming fourth-generation Domane, Trek Segafredo raced to first and third recently. Officially, that new frame the team is racing so well still doesn’t exist and we have almost zero information on what it offers, so in the meantime, the current/outgoing Domane works for us.

Fork

There are, of course, other Roubaix winning frames available but, as mentioned above, the frame provides the basis for the entire build and as such compatibility was a key consideration. One might assume the two IsoSpeed systems on Trek’s Domane frame might provide enough cobble smoothening for one bike, and Deignan’s Roubaix victory seemingly confirms that. But we love the bonkers Roubaix bikes of a seemingly bygone era and were not about to miss our chance to include a suspension fork in a modern Roubaix bike.

Ah, gravel suspension forks. Of all the contested use cases and merit of gravel suspension forks, the one thing everybody we spoke to agreed upon was a gravel suspension fork’s usefulness on the cobbles of Roubaix. Fox, BMC, RockShox, and Lauf all have gravel suspension fork offerings. With 30mm of travel and a progressive spring rate, the smallest increase in the axle-to-crown distance, and lower weight, we opted for the Lauf Grit SL.

The springs on the Lauf Grit SL are made of S2 glass fibre, said to be “extremely tough on hits and flexible in the direction of the travel.” If there is one thing Roubaix has plenty of, it’s “hits”. From the bone-rattling pave, to huge holes where cobbles once lay, and from the ramp back onto the smooth tarmac to unpaved dusty ditch tracks riders seek in a bid to escape the cobbles. Suspension might not be an absolute necessity for Roubaix, but with more than 50km of cobbles and big hits squeezed into the last 150km of the race, it’s certainly desirable.

Oh la la, real suspension is back at Roubaix.

Sure, the Grit SL and Domane are not the perfect fit. The increased axle-to-crown has a significant impact on the geometry and handling, and in the words of CyclingTips Editor in Chief guinea pig, “I wouldn’t want this fork on this bike any other day of the year”. But for the one proper pavé day of the year, it is perfect, and more importantly, a pretty flippin’ cool hark back to the 90s era of bonkers Roubaix bikes.

The tyre clearance with the Lauf forks could almost be measured in feet rather than mm.

Wheels

Long before the terms CdA (Coefficient of drag x frontal area) and Crr (the coefficient of rolling resistance) were ever uttered in the pro peloton, every rider understood the importance of wheel and tyre selection in conquering the cobbles. Aluminium box section rims with 32-spoke wheels and tubular tyres were seen as the only true option and thought to offer improved comfort and reliability over the pave. Fast forward a decade or two and those classic wheels have disappeared as the entire peloton has realised not only are aero carbon wheels faster, but also now offer more compliance and comfort than their shallower predecessors. In stark contrast to even a decade ago, these days no one lines up for Roubaix on aluminium, shallow, or 32 spoke wheels. The question is no longer whether deep aero wheels are suitable for Roubaix, but rather how deep and how aero can we go.

Slowly but surely tyre trends are also changing. Whereas a half-decade ago 100% of the Roubaix peloton raced on tubulars, more recently a rough estimation suggests as much as 80-85% of the 2022 peloton raced on tubeless. All four winners of the race in the past seven months raced on tubeless tyres, further indication of the tubular demise. If I can continue stating the obvious for a second more, tyres are also getting wider. The 25mm and 28mm widths once considered only suitable for Roubaix and too slow for any other race are now the norm in pro racing, and almost the entire peloton is racing on 30 and 32mm wide rubber at Roubaix. The increased width, volume, grip, and decreased pressure all make for a smoother ride over the pave and less chance of falling foul to pinch flats or into gaps between the cobbles.

All this considered, it was clear the best bike for Paris Roubaix should have aero wheels and wide tyres, the only issue being that typically the wider rubber negatively impacts the aerodynamics of the deeper rim. It was Silca’s Josh Poertner I first heard mention the Rule of 105. The Rule of 105 states that the rim must be at least 105% the width of the tyre if the airflow from the tyre is to reattach to the rim and create the aerodynamic benefit associated with deeper rims. Once we had decided on a minimum 30mm wide tyre, the issue was finding a rim 5% wider than that bulbous tyre.

That’s where Hunt’s Limitless 48 Aero (and super wide) wheelset comes in. Claimed to be the world’s fastest disc brake wheelset up to (and including) 50mm deep rims, the Limitless 48 rims tick the aero box, but more importantly, with a 35mm wide extra rim those aero gains are, hopefully, not lost to the wider tyre. Add to that the tubeless compatibility and the Limitless 48 was the closest match to the wheelset we had set out to include.

As for the rubber, we already knew it had to be wide, tubeless, and of course, tan walled. In keeping with the “the Rule of 105” our tyres could be up to a maximum of 33mm wide, and so the Challenge Strada Bianca TLR 33mm again ticked all the boxes. While not the absolute fastest tyre available, the Strada Bianca has a good mix of relatively low rolling resistance and high puncture resistance. While faster tyres are faster when moving, nothing is slower than a punctured and stopped tyre. Slightly disappointingly, the Challenges measured in at 31mm when mounted to the Hunt wheelset, and were a proper challenge (pardon the pun) to mount. Still, they met most of our requirements for the perfect Roubaix build.

Build kit

Frame, wheels, and tyres selected, the next major decision was the groupset. This was a less straightforward decision. There were pros and cons specific to Roubaix with every setup we looked at. Ultimately we settled on the SRAM Red Etap AXS groupset for several reasons. In no particular order other than the sequence with which our website arranged the photos in the album above, here is our reasoning for selecting SRAM Red for this particular use case.

Intuitive shifting

Riding and racing cobbles is tough. How can I explain this for those who have never experienced it? Imagine all the pain and cross-eye inducing oxygen debt of a three-minute maximal effort, at speeds most of us only experience while descending, while riding a mechanical bull, blindfolded by dust or mud, for hours on end with only minutes of recovery at a time, through a sea of fans millimetres from 150 other riders swerving, crashing, and attacking left right and centre. To put it mildly, the whole experience is chaotic, distressing, far from comfortable and quite disorientating, not the average weekend ride. Anything that can make the basic controls of a bike more intuitive and accessible is a good thing. For that reason, the single trigger, single function of SRAM’s large and easily found shifter triggers is crucial. Campagnolo’s lever and thumb shifter could have offered a similar solution, but with the recent addition of its wireless Etap blips, SRAM now offers a shifting solution for the bar tops position most riders adopt on the long cobbled sectors. I rode Arenberg for the first time last October and while the SRAM levers offered that simple unconscious shifting, there were times I wanted to shift gear but didn’t want to move my hands from the bar tops to the levers. With tops-mounted single function blips, this bike offers the same simple shifting with the security of both hands on the tops.

1X drivetrain

1x road is not for me, yet. But much like the Lauf forks on a road bike, if there is one race or sportive of the year where it works, it’s Roubaix. The X-Sync narrow-wide tooth profile should provide improved chain retention, while the single chainring and complete lack of a front derailleur eeks out a further aero efficiency improvement. Every little bit helps when speeds are high and we have a suspension fork up front. Furthermore, the large 54t chainring SRAM supplied should provide a small bump in drivetrain efficiency.

Clutch and cassette

Out back, the Red Etap AXS rear derailleur features a clutch as standard, which should further improve chain retention across the rough pave. The 10-28 cassette is again not something most of us will choose for everyday riding, especially with a 54t up front, but the smaller jumps between sprockets will make for smoother transitions between gears on the pave and less time spent over or under geared. The whole setup has Roubaix pedigree also, with both Lizzie Deignan and Elisa Longo-Borghini racing similar 1X SRAM drivetrains to victory in Paris Roubaix.

Not so typical marginal gains

On the theme of every little bit helps, I’m a firm believer that any gain is a gain worth having. While some might scoff at the difficult-to-quantify aero, rolling resistance, and drivetrain efficiency gains, they usually aren’t hurting performance. Hence the 1X setup here, the close-ratio cassette, and the aero pedals I’d have used. Every watt is a prisoner, and as such CeramicSpeed answered my requests for a UFO treated chain, coated T47 bottom bracket, and the always-contentious oversize pulley wheel system. The SRAM drivetrain is widely regarded as not the most efficient option on the market, so my hope was waxed chains, ceramic bearings, bigger chainrings (and in turn sprocket selection), and OSPWs might balance out any losses.

You might now be questioning what’s not so typical about those. CeramicSpeed components are perhaps the most typical marginal gain one could reach for. Fear not, we have plenty of cobble gobbling gains to share.

First up from Mr Marginal Gains himself, Josh Poertner, is the Silca Sicuro bottle cages. While not providing any aero or drivetrain efficiencies, these bottle cages might actually be a gross gain (Google’s answer to the opposite of marginal). Remember that description of riding cobbles above? Add to that a shocking number of flying bidons vibrating free of the usually perfectly adequate bottle cages like fighter jet ejector seats, ready to whack you or your front wheel. Just ask Geraint Thomas or Fabian Cancellara what a bidon can do to your chances of winning a race. Thomas and Cancellara both suffered the immediately obvious effect of a rider losing a bidon, what is less obvious is the impact on the rider who lost the bottle. Studies suggest a 2% drop in hydration can result in a 20% drop in performance. Hydration is not a marginal gain, it is essential to any success and so bottle retention is by extension essential to success. The Sicuro (Italian for safe) is not only beautifully classic looking and lightweight but it is said to provide unrivalled bottle retention.

Sticking with Silca, anyone who has listened to the Marginal Gains podcast will know about hysteresis, comfort, and Silca’s bar tape. While every traditionalist fibre of my being (there are some) was screaming DOUBLE WRAP BAR TAPE!, the head won out and we opted for Silca’s Nastro Cuscino 3.75 bar tape which Silca claims features “the most advanced foam ever used in bar tape.” What I can say is it feels cushioned and grippy, which seems good for pave bashing. Silca also provided its new Ultimate tubeless sealant to help stave off any pesky punctures. It ended up coming in handy as Caley put a small hole in the sidewall of the front tire which healed quickly.

Under that bar tape, we toyed with the idea of including alloy bars, solely because crashes are a thing at Roubaix and drops broken by impacts are also a thing. In the end, confident our new build would leave us so far in front of the peloton there was a greatly reduced risk of crashing, we opted for Bontrager’s Pro IsoCore VR-CF carbon bars. The Isocore carbon handlebar features continuous inner-laminar technology, said to reduce road vibration by 20%. More dampening is never a bad thing at Roubaix. The bar diameter is thinner to assist with dampening, but Bontrager supplies EVA pads to sit between the bar and tape and provide a more familiar girth. The pads double up neatly to at least let me imagine I did in fact choose the double wrap tape.

The 140mm Zipp Sprint SL stem was a last-minute addition to offset the reduced reach created by the knock-on effect of the increased axle-to-crown height of the Lauf forks. Inside that steerer tube we opted for a longer compression bung just, as we say in Ireland, “to be sure to be sure”.

Saddle wise, there was only ever one option. The S-Works Romin Evo was one of my top ten things I loved in 2021 and the most comfortable saddle I’ve ever sat on. While always important, saddle comfort is even more important in an event where your rear will take an awful bashing across 50+km of pavé.

Could it be better?

So with all these equipment choices, optimisation, Roubaix-specific gains, and a dollop of traditional aesthetics, that is our current best build for Paris Roubaix. I say current because there are several tweaks and tech upgrades we didn’t include but feel the ideal Roubaix bike still requires.

Number one on the list of “wanted to but didn’t” Roubaix hacks is tyre inserts. Another technology whose merit for road riding is disputable, like gravel suspension and 1X, tyre inserts are a no brainer for Roubaix. Tyre pressures are dropping annually at Roubaix. This year we saw pressures as low as 2.5 (36 psi) bar in the women’s race and 3 bar (43 psi) in the men’s. Those pressures provide a smoother ride over the cobbles but come at the risk of rim impacts causing untold damage to the rim. Tyre inserts can protect the rim, and provide a run-flat solution in the event of a puncture. So why then did we not include inserts? Unfortunately, the decision came down to a last-minute compatibility issue. The gravel Cushcore inserts we had were always going to be a tight fit in the 33mm wide tyres, but when the Challenges measured in at 31mm, I didn’t waste my thumb skin even trying.

Sticking with the tyre pressure theme, the conundrum for Roubaix riders is achieving a pressure suitable for both the smooth tarmac sections and the rough pave sectors. Ever since I tried the Graava hub-based tyre pressure management system at last year’s Eurobike, I thought it might be perfect for Roubaix. The option to ride with 70-80psi for the first 100km on smooth tarmac before dropping the pressure to ~50-55psi for the remaining 160km with 50+km of pave could be a game-changer. Ultimately, we decided against including tyre pressure management just yet, you can imagine our collective “oh merde” moment when it was suggested Team DSM may race with a similar system.

So why not manage our tyre pressure? The answer is aero, Graava only offers its KAPS system with a 30mm rim. The ideal solution would have been to build the Gravaa KAPS hub into a Hunt Limitless 48 wheelset for aero and pressure management, but ultimately there wasn’t time to explore if this was even possible. Maybe next year.

Speaking of that Hunt Limitless 48 wheelset. Had we known the Challenge tyres would measure in at 31mm wide when mounted we could have opted for Hunt’s slightly narrower but much deeper Limitless 60 wheelset. With a 34mm wide external rim width, the 31mm tyres would still have kept within “the rule of 105” and the extra depth is presumably even more aero.

Last but not least were cross top brakes and a chain catcher. Yes, cross top brakes are dying out in the World Tour peloton, but I have a feeling this was sped up by hydraulic disc brakes and the old cyclocross style brakes might still provide an edge for the pave sectors with twists and turns or even just quicker access to the brakes int he event of a crash in front. The Shimano GRX hydraulic cross top brakes were a strong lure to go with a Shimano groupset, but ultimately we went with SRAM, which doesn’t offer a gravel cross top hydraulic brake or have any plans to do so. Yes, we asked. As for the chain catcher, shipping delays meant it arrived after Roubaix week.

Riding the best bike for Paris Roubaix

With the build complete the only thing left to do was to test if it is actually any good. That “honour” was left to CyclingTips’ Editor in Chief Caley Fretz, who with almost zero warning and no idea of all the prep that went into this build was told he had to ride the notorious Trouée d’Arenberg five star pave sector. Not only that, but with almost zero training, closer to zero form, and almost no warm up, Caley would have to try to beat his personal record through Arenberg. A PR Caley set riding pretty hard during the Challenge Roubaix sportif back in 2017, in a group, with significantly better form, and plenty of warm up. Given all the caveats, surely if he could go faster this year, it had to be largely thanks to the bike.

Did he succeed? Watch the video above to find out.

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