A sprocket includes a sprocket body, first and second teeth alternatively arranged radially around an outer periphery of the sprocket body, a driving and a non-driving sides respectively defined on the first and second teeth in the driving direction and the non-driving direction, a recess defined between each first tooth and one adjacent second tooth, the first and second teeth each having a first or second tooth tip, a first groove and a second groove respectively extended from sprocket body to the first tooth tips of each two adjacent first teeth and form a thickness of said first teeth, that said first teeth is axially wider than said second teeth. Each first tooth includes two first front chamfers respectively disposed on the said first tooth flank of said two opposite radial surfaces and located on the intersection of said drive side of said each first tooth and said first and second grooves of said sprocket body. In order to avoid friction between the first teeth and the inner link plates while the sprocket is rotated by the chain.

A sprocket includes a sprocket body, first and second teeth alternatively arranged radially around an outer periphery of the sprocket body, a driving and a non-driving sides respectively defined on the first and second teeth in the driving direction and the non-driving direction, a recess defined between each first tooth and one adjacent second tooth, the first and second teeth each having a first or second tooth tip, a first groove and a second groove respectively extended from sprocket body to the first tooth tips of each two adjacent first teeth and form a thickness of said first teeth, that said first teeth is axially wider than said second teeth. Each first tooth includes two first front chamfers respectively disposed on the said first tooth flank of said two opposite radial surfaces and located on the intersection of said drive side of said each first tooth and said first and second grooves of said sprocket body. In order to avoid friction between the first teeth and the inner link plates while the sprocket is rotated by the chain.

A device for retaining a bicycle chain on a sprocket includes a base plate defining a plurality of fastener openings centered on an origin. A center of each of the plurality of fastener openings is disposed at a first radial distance from the origin. The origin defines an axis extending substantially orthogonally from a plane defined by two lines extending from the origin and at least two centers of the centers of the plurality of fastener openings. A first guard is secured to the base plate and includes a first guard retaining surface including a first curved surface defined by a second radial distance from the axis that is greater than the first radial distance and a first guard guiding surface having a first end adjacent the first guard retaining surface and a second end distal from the first end. The first end is disposed at the second radial distance from the axis. The second end is disposed at a third radial distance from the axis. The third radial distance is greater than the second radial distance. A second guard is secured to the base plate and includes a second guard retaining surface including a second curved surface defined by the second radial distance from the axis. A second guard guiding surface has a first end adjacent the second guard retaining surface and a second end distal from the first end. The first end is disposed at the second radial distance from the axis. The second end is disposed at a fourth radial distance from the axis. The fourth radial distance is greater than the second radial distance.

A device for retaining a bicycle chain on a sprocket includes a base plate defining a plurality of fastener openings centered on an origin. A center of each of the plurality of fastener openings is disposed at a first radial distance from the origin. The origin defines an axis extending substantially orthogonally from a plane defined by two lines extending from the origin and at least two centers of the centers of the plurality of fastener openings. A first guard is secured to the base plate and includes a first guard retaining surface including a first curved surface defined by a second radial distance from the axis that is greater than the first radial distance and a first guard guiding surface having a first end adjacent the first guard retaining surface and a second end distal from the first end. The first end is disposed at the second radial distance from the axis. The second end is disposed at a third radial distance from the axis. The third radial distance is greater than the second radial distance. A second guard is secured to the base plate and includes a second guard retaining surface including a second curved surface defined by the second radial distance from the axis. A second guard guiding surface has a first end adjacent the second guard retaining surface and a second end distal from the first end. The first end is disposed at the second radial distance from the axis. The second end is disposed at a fourth radial distance from the axis. The fourth radial distance is greater than the second radial distance.

Methods and apparatus for a composite bicycle front sprocket are disclosed herein. One embodiment discloses a composite bicycle front sprocket assembly having an outer assembly of a first material. The bicycle front sprocket assembly also has a center assembly of a second material. The center assembly is disposed at least partially within the outer assembly. The center assembly is irremovably coupled with the outer assembly. The center assembly is irremovably coupled with the outer assembly without an external fastening device to irremovably couple the center assembly with the outer assembly.

Methods and apparatus for a composite bicycle front sprocket are disclosed herein. One embodiment discloses a composite bicycle front sprocket assembly having an outer assembly of a first material. The bicycle front sprocket assembly also has a center assembly of a second material. The center assembly is disposed at least partially within the outer assembly. The center assembly is irremovably coupled with the outer assembly. The center assembly is irremovably coupled with the outer assembly without an external fastening device to irremovably couple the center assembly with the outer assembly.

A high-strength chain plate structure comprises an inner plate body and an outer plate body. The inner plate body has a first waist portion provided with a first receiving portion and a first outer side portion. The first outer side portion has a first slope. The first slope and the first waist portion form a continuous two-step structure. The outer plate body has a second waist portion provided with a second receiving portion and a second outer side portion. The second outer side portion has a second slope. The second slope and the second waist portion form a continuous two-step structure. The tensile strength, impact resistance and torsion resistance of the chain can be improved.

A high-strength chain plate structure comprises an inner plate body and an outer plate body. The inner plate body has a first waist portion provided with a first receiving portion and a first outer side portion. The first outer side portion has a first slope. The first slope and the first waist portion form a continuous two-step structure. The outer plate body has a second waist portion provided with a second receiving portion and a second outer side portion. The second outer side portion has a second slope. The second slope and the second waist portion form a continuous two-step structure. The tensile strength, impact resistance and torsion resistance of the chain can be improved.

A bicycle sprocket includes a plurality of sprocket teeth. The plurality of sprocket teeth includes at least one first tooth and at least one second tooth. The at least one first tooth has a first radial-tooth height. The at least one first tooth has a first chain-engaging axial width which is smaller than a first distance defined between opposed outer link plates of the bicycle chain and which is larger than a second distance defined between opposed inner link plates of the bicycle chain. The first radial-tooth height is greater than the first chain-engaging axial width. The at least one second tooth has a second radial-tooth height. The at least one second tooth has a second chain-engaging axial width. The second radial-tooth height is greater than the second chain-engaging axial width. The first radial-tooth height is greater than the second radial-tooth height.

A bicycle sprocket includes a plurality of sprocket teeth. The plurality of sprocket teeth includes at least one first tooth and at least one second tooth. The at least one first tooth has a first radial-tooth height. The at least one first tooth has a first chain-engaging axial width which is smaller than a first distance defined between opposed outer link plates of the bicycle chain and which is larger than a second distance defined between opposed inner link plates of the bicycle chain. The first radial-tooth height is greater than the first chain-engaging axial width. The at least one second tooth has a second radial-tooth height. The at least one second tooth has a second chain-engaging axial width. The second radial-tooth height is greater than the second chain-engaging axial width. The first radial-tooth height is greater than the second radial-tooth height.