The road you ride on

Road cycling. We think about cycling all the time but when was the last time you ever considered the road? It is just there. Perhaps you know where the rough sections appear on your riding routes, but what makes one road smooth and another rough? What makes a road?

History

The earliest roads were forest trails. Visit woodland today anywhere in the world and you’ll find trails worn by animals, whether a fox in Europe or an elephant in Africa. Their weight firmed the ground underneath preventing new plants from growing, and their passage pushed foliage aside, thus clearing a route. In time humans started using these paths and began to clear the way, breaking branches and pushing away stones. The wheel was invented and greater loads needed better trails; roll through history and various civilisations began to use paving, marking the move from simple paths created by common passage to routes that were planned and engineered: the road was born.

From 4,000 BC some civilisations were beginning to pave routes and others were using logs for Corduroy. These were the first roads. 2,000 years later a road in Crete was formed with different layers of material and finished with flagstones and drainage ditches. Another 2,000 years and the Romans were building a layer of crushed stone for drainage over which they put cobbles, a technique still used today.

The road to today

We cannot credit a single person for inventing roads but Pierre-Marie-Jérôme Trésaguet deserves a mention. A French engineer, he sat down to write guidelines for the construction of roads. In 1775 he became Inspecteur Générale for roads and bridges in France and the country began updating paths and tracks. Trésaguet insisted on excavating the ground, installing a layer of large rocks and then adding finer layers of gravel on top, all with drainage channels by the side. Like that, horse-drawn carriages could ride smoothly across mud-free roads as water would now drain away.

The next prominent name in early road construction is John Loudon McAdam, a Scot whose name lives on today thanks to macadam and tarmac. Macadam is the use of soil and stone that is then rollered into place to form a compacted layer that resists the passage of traffic, horseshoes included. This technique is still in use the world over and today cycling races use such roads in the strade bianche of Tuscany or the Colle delle Finestre, a regular in the Giro d’Italia which was built for the Italian army.

Tarmac then involved spraying hot tar – a thick extract from petroleum – on top of the macadam to bind the gravel as the liquid cooled and hardened – a technique used on unrollered paths in Babylonian times. Tarmac, when combined with Macadam, became the modern way of building roads.

Today

Contemporary roads use asphalt concrete. Asphalt is also known as tar or bitumen. A new road will see the route excavated and a layer of hard rocks compressed in place, a technique used in ancient times and refined by Trésaguet. Then comes Macadam’s contribution with the layer of aggregates (ie gravel) mixed with melted bitumen pour in place. This is then compressed by a heavy roller and left to cool, leaving the blacktop road surface that our sport relies on.

Variety

Roads vary. French TV commentator Jean-Paul Olivier once described a road as being “as rough as a cat’s tongue.” Some stretches of road are paper-smooth whilst others are rough. Construction techniques, uses and budgets all play a part here. More rural roads in Europe are often “chip seal”, also known as “tar and chip”. Here some liquefied tar is poured on the road and then gravel is spread on top.

The aim is that the gravel sinks into the tar, either under the weight of a heavy roller or often in France, the weight of passing traffic. The loose layer of gravel is to be avoided if you are on a road bike because even if you’re happy on the loose stuff, the liquid tar underneath is just waiting to ruin your tyres and splatter your bike. Once settled the gravel is effectively glued into the tar but you have to ride over the stones, creating the rough feeling. This is much cheaper than asphalt concrete.

Other parts of Europe see winter damage and subsidence. Some Alpine roads get smashed by coachloads of tourists and subzero temperatures, they are relaid every year. But away from the resorts the frost is left to crack and shatter the road. And in Belgium especially you will find the betonweg or concrete road with its infamous gaps.

Modern roads also feature additives, for example rubber is added to the asphalt to soften it a touch, offering improved grip and above all, better acoustics. Residents near busy road junctions get quieter routes.

Engineering

I’ve explained the methods behind their construction but surely the greatest engineering comes in the form of bridges and, for me, mountain passes. The two meet occasionally when the Tour de France crosses a bridge like the Pont de St Nazaire that is so long that it counts for the mountains competition.

Mountain passes existed long before roads, but the act of surfacing a route across a mountain has given races like the Tour de France the theatre that makes them so great. Hairpin bends are works of engineering but at times things of beauty and of course, thrilling too. The sporting battles and scenery granted by mountain roads are supreme. Cyclists from around the world visit these roads because of their legendary status; the strip of tarmac is a field of dreams.

Roads impose. Paths are carved into the rock, nature is disfigured. There is something impressive about a straight road; the Romans knew this, and Napoleon’s armies marched along linear avenues. But even if it is a false pretense, I prefer roads that work with the environment, whether following the shape of a river valley or twisting like an ancient trail through woodland.

Conclusion

Roads are the venue for our sport. They might just be there, a drab grey surface, but without them there’s no road cycling.

We enjoy moments when races leave the tarmac to use cobbles or gravel, but note even these sections are heavily-engineered with their drainage channels, camber, and design. And if we celebrate some mountain passes, give thanks for the humble strip of tarmac in front of your home.

Photo: the main photo above is from Mavic’s website where it accompanies their footwear. I think it is the Trafoi hairpins of the Stelvio pass in Italy. It makes an impressive desktop background and the full image is here. Thanks also to Zachary Olson for collaborating on this piece.