Ask any racing cyclist in the other disciplines and if they have raced with any serious intent they will have used tubular tyres. Tubular tyres were the original bicycle tyres, and comprise of a tube sewn within a closed cylinder. The tubular is then glued to the concave surface of the rim.
Advances in material then lead the development of clincher tyres and rims … the tyres we as MTBers are all familiar with, or “high pressures” to the roadies. This is much more convenient as messy glues and the complicated process of fitting the tubulars is no longer necessary (multiple layers of glue are needed, and tubular tyres must be stretched prior to fitment).
Tubular tyres are expensive, can be fragile, are tough to change in the field and reduce the possibility of tread changes as conditions dictate. The Pros are lucky to have team mechanics! And having a tyre glued on is a real pain when you puncture! Furthermore, there is a risk an improperly glued tubular can “roll” off the rim.
Yet tubulars retain significant advantages, and this is why they are still so popular at the elite levels of our sport. The Tour de France field still use tubulars almost exclusively. As do World Cup track cyclists and even our cyclocross cousins. So why are tubulars still so popular, despite the significant disadvantages? It boils down to several reasons:
Weight – since the tubular rim needs no bead hooks, rims can be made lighter. Considered as a complete system of rim, tube and tyre a tubular system has weight savings vs the clincher setup.
Ability to run high pressure – trackies love tubulars as they can run high pressures of up to 200 psi. Since clinchers rely on the bead hook to hold the tyre, the rim must be able to cope with the pressure exerted by the tube within the tyre. For this reason clincher road rims have max pressures of around 140 psi. Within the MTB domain, lightweight rims such as Stans NoTubes Podium MMX have max pressures of 33 psi as they aren’t built to handle more pressure. So Indoor Velodromes resonate with the sounds of tubulars at super high pressures as the trackies chase low rolling resistance.
Ability to run low pressure – as tubeless has become so widely accepted in the MTB world the main reason isn’t weight but the ability to run low pressure. There is still a practical limit to how low you can drop the pressure with a tubeless setup as the risk of “burping” the bead goes up as the pressure drops. Since the tubular is glued on, it can maintain a low pressure as it doesn’t rely on tyre pressure to hold the bead on. This is used by the elite cyclocrossers such as Sven Nys, Niels Albert and all the other Belgies as they chase grip and control in mud. Pressures as low as 20 psi aren’t unheard of. As the pressure falls, contact patch increases so a smaller tyre can offer more grip. This leads us to …
Bump absorbancy – lower pressures offroad (both CX and MTB) allow for a cushier ride and more shock absorbancy. This is important for the ‘crossers as they have tyres as thin as 33 mm and not much air volume.
Resistance to pinch flats – since off road we are chasing low pressure, the risk of pinch flats increases as there is less air to prevent the snake bite of the bead hooks and the tube. Again, the low pressures cyclocrossers use would be impossible with clinchers, and this is why elite cyclocross is so focussed on tubular tyres. Similarly, bumpy cobbled Classics like Paris Roubaix use tubulars almost exclusively as in order to gain comfort and shock absorbancy over the rough cobbles lower pressures of around 90 psi are required and the risk of pinch flat increases.
And the final beneficial characteristic:
Ability to ride a flat tyre as it is still attached to the rim – a great safety feature on a velodrome or high speed descent no matter the discipline.
MTB tubulars had been experimented with by Vittoria and Gary Fisher, who had pioneered a tubular tyre called Fast Trak but it never caught on. Maybe the advantages for the other disciplines just didn’t apply? Or maybe the time just hadn’t been right. The next instalment will look into this further.