the point and rhythm of the initial roller to sprocket contacts are altered for each tooth profile 302 304 since profile 304 does not have a tangential contact the sprocket chordal pitch is necessarily shorter than the chain pitch to facilitate the u201c staged u201d roller tooth contact in addition chordal pitch reduction also provides roller to flank clearance as the roller exits the sprocket wrap back into the strand added chordal pitch reduction when used is preferably in the range of about 0 005 to about 0 030 mm the staged roller contact for tooth profile 302 may be further assisted by providing a sprocket tooth pressure angle u03b3 that is substantially less than the iso 606 standard pressure angles u03b3 equal to or very close to zero 0 or even negative pressure angles are contemplated fig2 illustrates the tooth profile 304 overlaid with the tooth profile 302 phantom an engaging roller is shown at the onset of initial tangential contact at point a along the engaging flank of the tooth profile 302 the engaging roller will maintain contact with the engaging flank until it is at full mesh and seated at points b and c as previously described with reference to fig9 the tooth profile 304 is overlaid on the tooth profile 302 to show that an engaging roller only has radial contact on the inclined root surface of the tooth profile 304 see fig2 a and 22.