Abstract: This chain is improved in such manner as to improve the guiding thereof by chain guide roller in a gear changer of a cycle. For this purpose, its outer plates (10) include along their edge (16) opposed to the side of the chain facing toward the sprockets with which the chain cooperates, a projecting portion (17) projecting toward the interior of the chain, these projecting portions (17) defining therebetween a gap (18) of reduced width in which is engageable the chain guide roller with a reduced lateral clearance. Preferably, the edge (16) is convex.