Challenge grifo open pro cyclocross bike tyredeveloped for the rigours of modern cyclocross cx racing, this race ready tyre provides exceptional grip and low rolling resistance as you tackle the more demanding of terrain and course conditions'. '.strtoupper('f')eaturing a handmade construction, this clincher model's casing is produced with technical materials like corespun a cotton and polyester combination'. '.strtoupper('c')orespun is a thread from which challenge obtain a very supple and strong casing with low weights'. '.strtoupper('t')he casings have a high tpi count that can reach over 300 tpi and production avoids any vulcanisation process to enable all materials to keep their suppleness and flexibility'. '.strtoupper('h')andmade cyclocross clincher tyrethe tread is slowly hand glued on the casing which is previously mounted and inflated on a rim'. '.strtoupper('b')y using this method, the tread is relaxed on the casing and does not suffer any tension when inflated'. '.strtoupper('t')he result of this is a lower rolling resistance, increase in comfort, more precise handling of the bike and better grip.increased comfort, flexibility and puncture resistanceto give the best possible grip in curves challenge uses materials to obtain flexibility and suppleness, which results in absorption of irregular surfaces giving to the cyclist the best possible contact patch'. '.strtoupper('t')he wheel avoids jumping and the tyre will deform and absorb the irregularities acting in some way as a shock absorber'. '.strtoupper('a') special fabric is placed between the tread and casing to increase puncture resistance pps puncture protection system technology'. '.strtoupper('c')lassed as one of the best all around cyclocross tyres ever created by the brand, the challenge grifo open pro cyclocross bike tyre excels in wet, dry, soft packed, rocky and root infested course conditions.features use cyclocross racing all around soft pack tyre type clincher size 700c type width 33mm internal rim width 15 19mm tpi 300 bead aramid casing superpoly flat protection pps recommended pressure bar 2.1 2.7 psi 30 40 tubeless ready no single or pair single weight 355gtechnologies challenge handmade clinchers hcl this handmade clincher is made from the same materials and processes as the brand's handmade tubulars but instead of sewing an inner tube inside the casing is wrapped around a aramid bead to form a tyre that fits on a clincher rim'. '.strtoupper('t')he hcl is moulded flat, not in a horseshoe like a tlr or vcl'. '.strtoupper('t')his shape allows the casing to naturally deform over surface imperfections and minimize rolling resistance.buy challenge wheels tyres from chain reaction cycles, the world's largest online bike store.