There's a French cycling saying, 'mettre un siffleur', that means to use your lightest and best tyres for big races – and Europcar were doing just that during the 2013 Tour de France with the 200g Boyau Siffleur tubular tyre from Hutchinson.
The name means ‘whistling tubular’ and echoes the singing sound made by rubber rolling over hot tar. The tyre is an extremely rare and fragile bird, however – so rare, in fact, that only Europcar have a limited supply. Sébastien Joly, directeur sportif and head of the French squad's research and development, dubbed them the "Rolls Royce" of tyres.
Because of their fragility they only got an outing when conditions were perfect at the 2013 Tour. Thomas Voeckler used them once, on stage 13 to Saint-Amand-Montrond, when the peloton faced crosswinds.
Each Boyau Siffleur's casing – the fabric beneath the rubber – has a threads per inch (TPI) count of 350 in a single ply. TPI count is often used as an indicator of tyre quality and suppleness, and 350 is extremely high. In general, the more supple the tyre the lower its rolling resistance.
The tyres can be pumped to higher pressures than normal, too, which can improve rolling resistance (up to a point). We're told Europcar use around nine bars (130psi) depending on rider weight and road surface.
22mm Hutchinson Boyau Siffleur tyre
Hutchinson engineer Norbert Gangloff said: "When the weather is good and the road is good and when all the conditions are right they can use this tyre, but only then."
The tyres aren’t new. Gangloff said Hutchinson used to supply Lance Armstrong with the tubulars, so it's technology that has stood the test of time.