The Betonweg

The spring classics are here and for all the talk of steep climbs and cobbles there’s another feature of Belgium’s roads that rarely gets discussed, the betonweg.

Many races in Flanders feature cobbles, from suburban roads with their decorative pavé to farm tracks surfaced with medieval stones. These can be flat sections or steep hellingen and they’re often strategic points in a race, crowds gather and they make for great TV.

But there’s also something else that’s part of the Belgian racing experience: the concrete road, known as the betonweg. Safer and smoother than the cobbles, Belgium has many rural roads surfaced with concrete instead of tarmac. These are cheap to build and work fine for the secondary road network. They are large blocks of concrete and separated by small gaps, partly for drainage but also to let the material expand on a hot day, to avoid the surface buckling under expansion.

Betonweg detail
Mind the gap

These roads aren’t crucial to the racing but they’re not without their problems:

  • The blocks are often laid with a central channel in the middle of the road, see the picture above. This gap is inconveniently the width of a wheel meaning a permanent “tram line” that can trap the careless cyclist, especially when riding in the bunch and the gap isn’t easy to spot
  • The concrete is smooth but each block has a gap meaning a constant thump… … thump… … thump every few seconds as you ride along. This only adds to the fatigue after hours of riding

These things don’t determine a race, no way. But they do drain a rider and, whilst not unique to Belgium, these roads are typical and as Belgian as a cobbled road. Look out for the betonweg.

41 thoughts on “The Betonweg”

  1. I think the purpose of the gaps is primary for expansion. In better sections the gaps are often filled with a sealant – tar, in order to inhibit water ingress. You are of course correct that these roads are a very familiar feature in Belgium.

    • Expansion, and obviously, contraction. Furthermore, unlike a tarmac carriageway which is flexible and can be laid in a continuous run with a big machine, concrete road is more low-tech and can be laid in manageable sections, typically 4 to 6m in length. This length provides a length that can sensibly be laid and finished in one hit, whilst keeping the expansion gap relatively narrow (expansion being proportional to length).

      The gaps are certainly not for drainage (there should be a cross fall to the outside of the road) and are typically filled with silicone or bitumen based sealant. Or grass. Or glass.

      The road I live on is concrete, but was covered some time ago with tarmac. I can tell because the surface is giving way over the joints beneath. Another few months and there’ll be some serious thump…thump…thump…

    • Actually, believe it or not, they’re mostly for shrinkage. Concrete shrinks as it cures and if you don’t reinforce it (expensive) it will crack, potentially randomly and dangerously. Think of the joints as effectively just regularly spaced and evenly sized cracks in predetermined places so the concrete doesn’t do it on its own, or at least is far less likely to. Here endith the materials science lesson (yes, I’m a structural engineer).

  2. We have these in Greece as well, especially were the road gets steeps and extra grip is needed!!! I climbed one in an MTB race..

    I think something similar can be found in GT stages as the Bola del Mundo or the Plan de Corones..

  3. Stannard ended up bunny hopping a couple of the central gaps in the later stages of DDV this afternoon. Must have looked incredibly weird to anybody who didn’t know what betonweg is.

  4. I love articles like this, details that most casual fans never notice. They give a real flavour of the nitty-gritty of racing.

    Thanks Inner Ring!

  5. These roads are very noisy for cars, the concrete has some kind of different accoustic aspect and there is the “punch” each time the wheels cross the gaps.

    Apart from some private roads, like to a TV relay antenna on the hill, I’ve only seen them in Belgium as full roads open to the public.

    • Sections of the M42 in the UK used to be concrete like this until very recently. I thought they were still like it, but I’ve just checked on Google Maps. On Streetview the carriageway is tarmac in both directions, but the satellite view shows the southbound carriageway is concrete –

      I think it was very hard wearing, but it was pretty unpleasant to drive on.

    • The German Autobahn was build that way during the war, so the german army could travel fast across the country.

      Its not that many years ago they where changed in the eastern part of Germany. I dont even know if they are all changed, bust the major ones are. I remember at trip for Hungary in the early nineties, That was a bumpy ride with a very annoying thump every 2 seconds.

      The trip where around 800 km so that was a lot of thumps on that trip

  6. There are a lot of these in Hong Kong. They spread over time so the little drainage channels become big gaps – bloody dangerous and bumpy every time you cross from one to another. Still gentler than the pave, though.


  7. You get quite a few of these in the East Anglia region of the UK, Norfolk and Suffolk in particular where they were service roads for the World War II airbases that are a feature of many villages.

    The Boudicca sportive makes a point of including a few miles.

  8. I remember these from the Boudicca last year.

    The roads around where I grew up where made of these too. A bit more suburban than WW2 air-force bases.

  9. Inrng for the details! 🙂

    In Flemish they’re also known as macadammen. Easy to remember as the gaps between the concrete plates make any bike giving that distictive “da-dam” sound.

    Be sure to eat some frieten or speculoospaste before you go and have a ride. There’s always a crosswind near you. 🙂

  10. Thankfully, most of my training routes avoid them!
    Can’t stand them!
    And there are plenty of them on secondary roads here
    in Oost Vlaanderen!
    Always angle my front wheel a touch when hitting the bumps
    in order to take the sting out of the contact point! Helps somewhat!

  11. Belgian race commentators used to use the sections of betonweg to measure gaps between breakaways and the peleton – “The breakaway has 30 betonwegs”. But this method died-out with the advent of GPS timing.

  12. There are some sections of motorway in Scotland like that, and on bridges too, where the gaps between sections are even bigger. Driving over the Forth Road Bridge in a car with “sporty” (i.e. harsh) suspension is not fun – thump, thump, thump.

    I remember driving over it with the wife and baby asleep in the car, only for both to be woken up by the thumping – cue grumpy moans from passenger seat and screaming from the back… joy :-)!

    • The gaps between sections on bridges shouldn’t be confuse with overall bridge expansion joints. Laid on the ground your betonweg segments expand/contract independently, but on a bridge they will also be subject to the expansion of the bridge itself. This is accommodated in expansion joints. Years ago these used to give one hell of a thump as you drove/cycled over, but they seem a lot smoother these days.

      • Yes, the ‘heavy impact’ on the Highways Agency budget due to ‘snake-bite’ claims by cyclists, ‘forced’ civil engineers to design smoother joints.

  13. The riders in the photo look like 15-stone monsters of men. It could be the ’79 Wigan RL team out for a spot of cross-training… if they knew what that was back then.

    Cyclists have really changed that much since 1980?
    On TV now they seem mostly jockey-sized or stick figures.

    • A good question. Those were the days when they ate steak for breakfast.

      Riders these days do focus a lot on being lean but that’s long been the case. Often photos make riders look big when they’re not. I keep meaning to write about this, how the camera can give the wrong impression.

      • A side shot of a rider can often make them look quite rotund. Usually a combination of relaxed stomach muscles and a lungfuls of air pushing the abdomen down further.

  14. One of our juniors has just been selected for the Norwegian national team which is going down there after Easter. I’ve told her to watch out for that central gap. Nasty.

  15. Tramlines in the road are horrid.

    Cycling from Manchester to Newcastle last year, just a couple of miles outside Manchester city centre a fellow cyclist slipped into a tram line, flipped over his handlebars and landed on his wrist.

    Ignoring the pain, and obvious embarassment, he hopped back on and carried on over the hills and Yorkshire moors to Newcastle his wrist turning darker shades of blue and purple on route. Upon reaching Newcastle and visiting A&E he found out he had fractured his wrist.


  16. Reminds of so many roads in our area of Iowa, USA. I call it “super-slab” and when old it’s very much not fun to ride a bike on. Not much of it in Italy, thank you! I’m sure after even the shortest Ronde route I’ll have had my fill of both this and the cobbled sections – but one must try it ONCE, right?

  17. There’s a road near me that used to have these concrete slabs. Every 15 yards it was ‘da dum’, ‘da dum’.

    Now they’ve long since tarmacced it, but guess what, cracks are appearing where the slots between the concrete were so now the ‘da dum’ is coming back!

  18. Great insight, as usual.

    A non sequitur… how about a piece sometime on one of the ubiquitous and oft-overlooked dimensions of bike racing– the motorcycles? Photo bikes, video bikes, support bikes for narrow alpine roads… Who pilots them, which makes are preferred, how have they evolved over time, etc. I think I see a BMW R100RS in the background of the betonweg shot…

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