Words by Rob Allen
This may prove contentious but we’ve initially chosen Challenge and Clement because both brands have superb pedigree and, we think, represent the benchmark in high performance ‘cross tyres. Remember we are looking at race performance here and that these are no holds barred race tyres, so they don’t score particularly well in puncture resistance or durability.
The Challenge Grifo XS offering is one of the most extreme file treads available. It rolls very fast and the side knobs give good grip in the corners, but the compound is quite waxy and we found that it gives no warning when it is about to let go on the limit. It’s clearly a fast tyre in a pretty narrow window of operation. We also had some success pairing a Grifo XS rear with an intermediate front such as the Grifo featured below.
The LAS is a different beast. Like all Clement clinchers it comes up pretty large (36mm on our Stan’s test wheels) which contributes to a “floatier” feel than the Challenge. The rubber is tackier to touch and the centre knobs are graded, being higher towards the edges and lower in the middle, which Clement claims helps rolling performance though we still felt that Grifo XS rolled marginally easier. The LAS is definitely grippier however, both in a straight line and in the corners.
Overall, we preferred the LAS, as it can be used in a wider range of conditions and is slightly more forgiving on the limit. But the Grifo XS works well in fast dry conditions, and would probably suit more experienced and skilful riders who can fully utilise its extra speed in trickier conditions.
We’ll be interested to see the new Challenge Chicane when we can get our hands on some to see how they stack up.
Intermediate treads work in mixed conditions, looser and greasier than file tread courses and will handle some mud. The Grifo is a well proven design, and still holds its own well. It’s grippy in a straight line and thanks to the supple carcass it rolls well too. On grassy courses we could hear the tread literally tearing the grass as we tipped into tighter corners. When the going gets muddy we found that the Grifo was a slightly better bet than the MXP, the slightly wider spaced knobs clearing the slop more quickly.
The MXP is wide, floaty and supple like its file tread and mud cousins. It’s exceptionally grippy with a comparatively aggressive tread and the same tacky compound as the LAS. We were able to run pretty 25 psi without pinch flats on our local ‘cross loops. It excelled in looser, greasier terrain compared to the Grifo, but again we felt it rolled marginally less easily on smoother surfaces.
We made this category a tie – both are excellent tyres, the MXP grippy and floaty, the Grifo faster rolling and better in marginal mud. Take your pick.
Muds are probably the most important category for UK based ‘cross racers. Mud dominates many courses from late autumn onwards and specialist mud treads can give a real advantage.
We have reviewed the PDX in great depth here previously. Suffice to say it is still, for us, the benchmark mud tread. Its grippy and clears mud exceptionally well, with the trademark Clement volume, supple casing and floaty feeling.
The Challenge Limus, however, has a large and loyal following in our regional series so we thought we would see what the fuss was all about.
The Limus’ 3 part blocks are chunkier than those on the PDXs and are closer together, which makes for a pretty aggressive tread. We found it was at its best in sloppy mud, with more viscous conditions challenging its ability to clear the mud and causing it to ‘ball up’. The bigger, more aggressive knobs also cause it to roll noticeably less well on hardpack than the PDX.
Whilst the Limus is a very competent mud tread, for us, unless the conditions are really sloppy, the PDX is a clear winner.
So there you have it. It’s not really possible to declare a clear winner as both brands offer excellent ‘open tubular’ tyres that are race worthy. The Challenge tyres would possibly suit more experienced riders, so Clement may just edge this one for their broader appeal. However, even if these are clinchers and not tubs, the truth is that with these tyres ‘broad appeal’ is perhaps somewhat limited to fairly serious cross racers…
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