An object of the present invention is to provide a chain and a chain transmission device capable of reducing sliding resistance of the chain to a guide lip portion and stably maintaining an oil film between the guide lip portion and an outer plate. Provided is a chain 20 wherein a plurality of link plates 40 and 60 include outer plates 60, each of the outer plates 60 has a pair of front and rear pin holes 61 into which connecting pins 50 are inserted, a guide-side end surface 62 that faces a traveling guide surface 81a side of a chain guide 80, and a contact convex portion 63 that protrudes from an outer surface of the outer plate 60, and the contact convex portion 63 is formed in an area between the pin holes 61 and the guide-side end surface 62 in a plate height direction.

An object of the present invention is to provide a chain and a chain transmission device capable of reducing sliding resistance of the chain to a guide lip portion and stably maintaining an oil film between the guide lip portion and an outer plate. Provided is a chain 20 wherein a plurality of link plates 40 and 60 include outer plates 60, each of the outer plates 60 has a pair of front and rear pin holes 61 into which connecting pins 50 are inserted, a guide-side end surface 62 that faces a traveling guide surface 81a side of a chain guide 80, and a contact convex portion 63 that protrudes from an outer surface of the outer plate 60, and the contact convex portion 63 is formed in an area between the pin holes 61 and the guide-side end surface 62 in a plate height direction.

A transmission system is provided that has a drive pulley, at least one driven pulley and an oil wet toothed belt. The toothed belt includes a toothing and a back, a first portion, wherein the toothing is coupled to the drive pulley, a second portion wherein the toothing is coupled to at least one driven pulley, a first taut branch which develops towards the driving pulley and a second slack branch which develops towards the driven pulley. The transmission system also includes a fixed containment guide having at least a first wall facing the toothing and/or the back positioned at a distance from the toothed belt between a minimum distance where at rest it is not in contact with the toothed belt and a maximum distance equal to 5% of the length of one between the taut branch and the slack branch.