Clément’s new file-tread tyre is named LAS – after Las Vegas's airport code – in honour of CrossVegas, arguably America’s biggest cyclo-cross event, and the venue for the brand's 2009 relaunch by Donnelly Sports (under license from Pirelli).
File-tread tubulars have their fans in 'cross due to their low rolling resistance and ability to conform to the terrain when run at low pressures, making up for their lack of tread grip. They excel on surfaces like sand, grass, snow and ice (in the latter situation, knobs would reduce the amount of surface area in contact with the slippery surface).
The Taiwanese-made LAS, however, is a clincher tyre, so it's even more course-specific than its tubular brethren. We’ve ridden it for close to two months and can confidently recommend it for sand and dry grass. Considering that it's a clincher and has minimal tread, we actually came away impressed with its performance on all surfaces.
We attribute the 352g aramid-Kevlar LAS’s prowess to two features: its healthy – albeit UCI illegal – 34mm size and the suppleness of its 128tpi casing, which is among the softest of any conventional clincher tyre we’ve ridden. In fact, the LAS rivals Challenge’s open tubular cyclo-cross tyre casing.
The casing is so supple that at 40psi the tyre feels like others clinchers with 30psi in them, and at 32psi – about the lowest we'll go with a clincher – it feels phenomenal; you can almost feel it conforming to the terrain. Still, as with any clincher there is an ever-present threat of pinch flatting.
The LAS tread is moulded out of 60a durometer rubber and features a progressive diamond-file pattern, with knobs that increase in size as they move towards the shoulder knobs, which are borrowed directly from the PDX, Clément’s mud tyre.
Clément have a patent pending on the LAS's progressive file design, where the knobs increase in size toward the edges
This tread pattern allows the rider to drift comfortably into a cornering angle, at which point the side knobs set and offer decent cornering grip. It works best in loamy soils or those with a consistent density, struggles on the dreaded loose-over-hard and, as expected, doesn't work in the mud. As with all clinchers, you can’t fall back on super-low pressures, so we wouldn’t recommend the LAS for snow or ice, either.
It doesn’t have a puncture resistant tread liner, which is one of the reasons it's so supple but also makes it subject to sharps, whether they be goat-head thorns, nails, glass or the like. In terms of tread wear, we'd list it as normal. Our front tyre is barely worn, while the back shows wear down its centre due to a good amount of road riding during our test.
All in all, Clément have created a very good file-tread tyre in the LAS and a tubular version will likely catapult it to the top of the file-tread tyre food chain, should the company choose to make one.