Cyclocross World Champion for years. Whether a Pro or just a hardcore rider Grifo is the tyre you need. Unbelievable grip with no rolling resistance compromise. All tubular and open tubular produced by Challenge are special products. Machines are not able to produce them and the manual skill required in each step to obtain a good quality standard is very high. The casing is produced with the latest technical materials like Corespun (a cotton and polyester combination). Corespun is a thread from which we obtain a very supple and strong casing with low weights. The casings have a high TPI count that can reach over 300 tpi. Our production process avoids any vulcanisation process to enable all materials to keep their suppleness and flexibility. The tread is slowly hand glued on the casing which is previously mounted and inflated on a rim. By using this method the tread is relaxed on the casing and does not suffer any tension when inflated. The result of this is a lower rolling resistance, increase in comfort, more precise handling of the bike and better grip. Hand made tubulars are well known by professionals and is this type of tyre that is preferred for the long stage races. To give the best possible grip in curves Challenge uses the most updated materials to obtain flexibility, suppleness and this results in absorption of irregular surfaces giving to the cyclist the best possible contact patch. The wheel avoids jumping and the tyre will deform and absorb the irregularities acting in some way as a shock absorber. A special fabric is placed between the tread and casing to increase puncture resistance PPS (Puncture Protection System) technology. Comfort means reduction of harmful vibrations for the wrists and neck, these vibrations, will end causing inflammatory problems, as a hard tyre will transfer all the vibrations directly to the racer body. Classed as one of the best all-around cyclocross tyres every created by Challenge, this tyre excels in wet, dry, soft packed, rocky and root-infested course conditions. Technologies: Challenge Handmade Clinchers (HCL): These Handmade Clinchers are made from the same materials and processes as our handmade tubulars but instead of sewing an inner tube inside the casing is wrapped around a aramid bead to form a tire that fits on a clincher rim. The HCL is moulded flat, not in a horseshoe like a TLR or VCL. This shape allows the casing to naturally deform over surface imperfections and minimize rolling resistance. A tubeless tire is moulded in a U-shape to make the sidewalls rigid, so the system does not “burp” or lose air when it deforms after it encounters a surface imperfection. The tubeless tire’s stiff sidewall compromises its ability to equal a supple HCL with a latex inner tube.