They are a 33C tyre but look much wider thanks to the very round profile they adopt once inflated. Our version has the white rubber that is allegedly meant to offer improved grip, though we are not sure how white it will be after a winter’s racing in British mud.
The Grifo XS file tread is designed to give you more speed on hard, dry days and as such we had these in mind for summer cx races. Best laid plans and all meant that didn’t happen, but given the climate down here in the South-east of the UK, there may be a few dry races in autumn/winter that we turn up at, so they may still have their chance to shine in those conditions.
Other than that, Challenge also rate them for ice, so that may be an interesting test should we have such a day. Challenge also say they are good on grass but we are not sure if that means the wet, slippery grass we get here, which is soon replaced by muddy, tyre turned gloop in most races; still we’ll soon see. Riders whom we have talked to about these tyres really rate them, when its dry…
The Grifo XS is of 300TPI (threads per inch) construction, which should make it very supple indeed, and uses a ‘super poly’ (polyester) casing for added durability with an aramid bead, which all adds up to a reasonable 355g tyre weight. The tyre has Challenge’s PPS puncture protection which is an extra couple of layers of puncture resistant fabric that sits between the casing and the rubber tread. That rubber is sourced locally at Challenge’s own factory in Thailand.
The suggested inflation of 30 – 90 psi seems reasonable, though we have already used them at 20 with no ill effects… We have dumped some tyre sealant into the tubes though to be safe. We’ll report back with a full test soon.
Challenge Grifo XS RRP. £52.00
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