Road to Roubaix, Part 1 | SILCA

Road to Roubaix, Part 1

Note: Before buying SILCA I was fortunate to spend nearly 15 years as the Technical director at Zipp.  I worked with the most amazing team of engineers and production specialists to create some amazing products.  This story would not be possible without the efforts and brilliance (and blood, sweat and tears..literally) of Michael Hall, David Morse, John Fearncombe, Nic James and many others.  Please check out the video produced on this by Zipp and other info from them over HEREThanks Everybody! 

One might think that the catastrophic failure of a carbon wheel is a particularly dramatic, loud, or impressive occurrence, but you would generally be wrong. In an ironic twist, you find that impacts at 90% of the energy required to create a failure, can sound like a gunshot, can wrench your handlebars from your hands, or nearly throw you from your bike. However, an impact at 110% of the energy required to break a wheel can feel quite minor, and the failure itself often sounds like a sudden crunching of paper rather than anything very dramatic. Like that, your wheel is destroyed, in a whimper rather than a bang.

So went the early days carbon wheel development for Paris-Roubaix.   It was 2006 and I was convinced that aerodynamic, carbon wheels could change the face of racing at Roubaix, yet we first had to build product that was capable of surviving the famed cobbles, and even more difficult, we had to convince the riders to actually use it!

Looking back, I see that this was the start of my obsession with tire pressures, quality tools, and optimizing the minutia of cycling details. I had spent the previous 7 years developing products for aerodynamic benefits and it had been a long and difficult road convincing top level athletes to use it in good conditions.   A project to finish carbon wheels at Roubaix felt like an entirely new adventure involving different skills and new learnings.

We began the Roubaix project in 2007 with two teams on tap for 2008, Slipstream and CSC, between them we had access to Magnus Backstedt, Fabian Cancellara, Nicki Sorensen, Roger Hammond and a crop of young and enthusiastic pros looking to find their way in the world. Pro cycling at that point (and still today) was held in tension between old-world beliefs and new world science, often the tension resulted in catastrophic combinations of both worlds.

Our focus was to get the more aerodynamic carbon wheels under these riders. We had done some testing with Cancellara in early 2008 at the San Diego low speed wind tunnel showing that 58mm deep carbon wheels would be some 28-34 watts more efficient (at 30mph) than the 32 spoke aluminum wheels they traditionally rode at Roubaix, so there was some interest by the teams and riders, but still far too much skepticism to make it a near term reality.

Poertner with Zipp R&D Director Michael Hall, Riis and Cancellara at the wind tunnel in 2007

Like the athletes, we believed that the real hurdle to bringing carbon wheels to Roubailx was going to be comfort. The entire world believed that there would be no way to achieve the ‘comfort’ or ‘compliance’ of box section wheels in deeper wheels. Afterall, we all KNEW that deeper wheels were stiffer, and therefore harsher, it had been written a thousand times and was therefore true. So in late 2007 we set out to understand the baseline standards for both durability and comfort in these ‘classics’ wheels.

An Instron machine, is generally the cornerstone of any good mechanical testing lab. Instron is the company most widely known for making this type of machine which looks like a large H sitting on a steel table. The machine works by driving a crossbar up or down at a very controlled rate, in the center of the cross-bar is a load cell and a gripper, or a pusher (anvil) which either stretch or crush the object being tested. An Instron can be used to test the strength and stiffness of most anything provided you have clever engineers to build the fixturing.

Setting up for radial stiffness test of a wheel with tire.

The initial testing was conducted with about a dozen wheels including ptototype Roubaix wheels, vintage Mavic Roubaix aluminum box section wheels, and the 2007 race favorite 32 spoke Ambrosio Crono box section rimmed wheels. After the first full day of testing, crafting new anvil geometries, re-thinking the fixtures, re-thinking everything we could be doing wrong, we realized that we weren’t doing anything wrong at at all: The box section wheels were in fact, radially stiffer than most of the deeper carbon wheels!

Now this wasn’t universal, deep rims with V shapes were very stiff, though even then the correlation to stiffness was more stronger to spoke count than to rim depth, with only the original 16 spoke Campagnolo Shamal being the outlier, though with a perfectly V shaped rim, and bladed 14 gauge (non-butted) spokes, this made some sense.

However, we found ourselves in possession of data that pointed to the fact that the conventional wisdom of an entire generation of cyclists, mechanics and even industry engineers was just generally plain wrong. In the years since, I’ve taken part in studies and even designed studies to look at these perception vs reality situations and know that perception and conventional wisdom generally win, but at the time, my 2007 brain was blown away by this information.


2007 Radial Stiffness Testing of various wheels

This information really changed the entire vision of the project for us. It was immediately clear that what we believed to be the major problem “how to make a deep carbon wheel as comfortable as a box section wheel” was not actually a problem at all, in fact, most everything we were making was already there. The real problem was going to be convincing the riders of this.

With this information in hand, the team built some 20 pair of prototypes and headed to a team camp just outside the dreaded Arenberg Forest.

For the uninitiated, the Arenberg is considered the most brutal sector of Paris-Roubaix, massively crowned stones, few decent lines, incredibly narrow, sloppy when wet, dusty when dry, and worst of all, an ever so slightly downhill run-in to the sector which narrows dramatically at the entrance. The top teams put maximum effort into getting their riders to the front, and that means 60+kph speeds as the riders hit the stones.  Oh yeah, and occasionally people have been known to steal a stone here or there as a souvenir..making for the most unbelievably dangerous hole in the ground you'll see on any racecourse anywhere in the world.

Stones at the entry to the Arenberg Forest Sector - 2008 Testing

The goal with the prototypes was to build sets of various strengths and stiffnesses to see what the riders would prefer as well as to determine the strength requirements of the rims. The test plan was to have them ride various lines to see if they could break the wheels and also to try and determine the handling characteristic the riders were after. Afterall, we knew that we could make the carbon wheels ‘comfortable’ enough, but could we make them last?

90 Minutes

90 Minutes was all it took for 4 riders to break 20 sets of wheels on that first trip. Hard to remember the other details, but unsurprisingly comfort didn’t really come into the equation for this test. Our team was needless to say, devastated.

Yet, the testing had revealed some very useful data, and by early spring 2008, we had 404’s measuring equal in radial stiffness to the Ambrosio Crono wheels, but at more than 2x the impact strength of before. An early test with Slipstream showed no issues in more than 40 passes through the forest when paired with 28mm Dugast tires. We were ready! Or so we thought..

I don’t remember much from the day of Paris-Roubaix 2008, but I do remember getting the phone call. “Magnus broke both of his wheels and could not rejoin, we need to talk.” Devastated.

For those of you who don’t remember this event specifically, we were thrashed in the media for attempting this. A major US magazine gave us a ‘Thumbs Down’ award for ‘putting sponsor desires above rider’s safety.’ The general lament was why we would ever even attempt this as EVERYBODY knew that it wouldn’t work and that there was little benefit possible, yet so much downside risk. In those dark moments afterward I even wondered why we had even spent so much time, energy and money on this..

At 7 AM the next morning my phone rang, it was that Magnus and I felt a tremendous sense of relief when I couldn’t detect any anger in it. Turns out he was spending the day with his wife and children at Disney Land Paris, they were having a good time, and he wasn’t blaming us (too much).  He pointed to some critical factors that may have caused problems, mainly, they had made the decision to switch to 24mm tires the night before the race as conventional wisdom held that in the dry, these narrow tires were faster. He soothed my worries by pointing out that he was more than 1 stone above his weight of last Roubaix (14 pounds..I had to look it up at the time) and that he didn’t blame us entirely thinking that the tires were a mistake since the testing was all done on 28mm. He also was the first to let me know that Martijn Maaskant a young pro with the team had finished 4th on a pair of 202’s which were not anything special we had produced for the race, he suggested we look at the dynamics of those wheels as Martijn was really happy with them!

The significance of this conversation cannot be overstated, in 24 hours we had gone from the terrible people who cost Magnus his race to learning the other side of the story that we had the first carbon wheel to ever finish in the velodrome at Roubaix, and it was nearly on the podium!

The lessons learned from those 202’s with 28mm Dugast tires would pave the path to a total rethink of team wheel, tire pressure and tire management, a rethink of rim geometry, tire/rim aerodynamics, tire/rim interface and ultimately Paris-Roubaix race strategy.

Read Part 2 HERE

Note: Before buying SILCA I was fortunate to spend nearly 15 years as the Technical director at Zipp.  I worked with the most amazing team of engineers and production specialists to create some amazing products.  This story would not be possible without the efforts and brilliance (and blood, sweat and tears..literally) of Michael Hall, David Morse, John Fearncombe, Nic James and many others.  Please check out the video produced on this by Zipp and other info from them over HERE Thanks Everybody! 

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