This tread is made up of low, closely spaced knobs, an effective tread for going fast over varied terrain. Surly chose 41mm because it’s meaty enough to conform to the ground surface, absorb irregularities and provide a decent sized contact patch. Both the 27 and 120tpi casings do a good job and feel lively, though the 120tpi is lighter, more supple, and features a folding bead.
ETRTO: 700c x 41mm
(622mm ETRTO, 41mm casing width) (Note: 23–30mm recommended rim size.)
Casing: 120tpi with Kevlar bead (465g, available on special order)
27tpi wire bead (650g)