Bicycle chain rings
Embodiments of the present invention include bicycle chain rings for bicycles having specially shaped ramps, tapers and profiled teeth for improved shifting performance. The embodiments of bicycle chain rings of the present invention may be configured for large chain rings on double cranksets and large and middle chain rings on triple cranksets. The embodiments of bicycle chain rings of the present invention may also be retrofitted to existing bicycle cranksets by replacing original chain rings. The embodiments of bicycle chain rings of the present invention may further be configured for any standard crankset mounting bolt configuration and for any suitable number of teeth.
1. A bicycle chain ring, comprising
an inner periphery forming an inner opening disposed in a surrounding configuration to an axis of rotation;
an outer periphery of the chain ring where a plurality of chain ring teeth emanate;
an inner surface extending between the inner periphery and the outer periphery;
a plurality of ramps disposed about the inner surface, wherein each of the plurality of ramps includes a lifting surface for initiating lift of a bicycle chain without assistance from the plurality of chain ring teeth, the lifting surface initiating lift of the bicycle chain by simultaneously engaging the bicycle chain at two or more distinct points during an up-shift;
at least one of the lifting surfaces extending radially along the inner surface from the inner periphery of the chain ring outward toward the outer periphery.
2. The bicycle chain ring according to claim 1 , wherein at least one of the lifting surfaces is curved in profile.
3. The bicycle chain ring according to claim 1 , wherein each of the plurality of ramps ends at a trough between two teeth, wherein one of the two teeth is partially cutoff.
4. The bicycle chain ring according to claim 1 , further comprising an inside taper gradually narrowing thickness of the bicycle chain ring, the inside taper located adjacent to each of the plurality of ramps.
5. The bicycle chain ring according to claim 4 , wherein the inside taper provides decreasing bicycle chain ring thickness in a direction opposite normal rotation of the bicycle chain ring during an up-shift.
6. The bicycle chain ring according to claim 1 , further comprising partially cutoff teeth located radially outward from an outer end of each of the plurality of ramps.
7. The bicycle chain ring according to claim 6 , further comprising a plurality of non-partially cutoff teeth in between each of the partially cutoff teeth, each non-partially cutoff tooth having an inside bevel located proximate its tip.
8. A bicycle chain ring, comprising
an inner periphery forming an inner opening disposed in a surrounding configuration to an axis of rotation,
a plurality of ramps disposed about an inner surface of the bicycle chain ring,
wherein each of the plurality of ramps is configured with a lifting surface protruding from the inner surface toward a smaller adjacent chain ring, and extending from a first radial position representing the inner periphery of the bicycle chain ring, outward to a radius measured from an axis of rotation out toward, but stopping short of, bottoms of troughs between chain ring teeth, the lifting surface having placement and length sufficient to engage and to lift the bicycle chain at two or more chain load points during an up-shift, the load points being directly under chain pivot axes.