This is a similar Knard tread we previously introduced on a 29 x 3ÃÂ casing, made up of low, closely spaced knobs, an effective tread for going fast over varied terrain. We chose 41mm because it's meaty enough to conform to the ground surface, absorb irregularities and provide a decent sized contact patch. The 120tpi is lighter, more supple, and features a folding bead.ETRTO: 650b x 41mm(622mm ETRTO, 41mm casing width) (Note: 23-30mm recommended rim size.)60 tpi with Folding bead (465g)