Bicycle crank arm and chainring carrier assembly

Abstract

A bicycle chainring structure is provided. The chainring structure includes a plurality of teeth disposed about the radially outer circumference of the chainring structure and a pairing feature including a wall forming a radially interior profile formed on the chainring structure, the radially interior profile defined by lobes extending radially inward. The chainring structure also includes a torque-transmitting coupling formed in the chainring structure, the torque-transmitting coupling including a plurality of chainring holes disposed in the radially inward extending lobes and configured to receive input torque from a crank arm and transmit the input torque to the plurality of teeth.

1 . A chainring structure, comprising:
 a plurality of teeth disposed about the radially outer circumference of the chainring structure;   a pairing feature including a wall forming a radially interior profile formed on the chainring structure, the radially interior profile defined by lobes extending radially inward; and   a torque-transmitting coupling formed in the chainring structure, the torque-transmitting coupling including a plurality of chainring holes disposed in the radially inward extending lobes and configured to receive input torque from a crank arm and transmit the input torque to the plurality of teeth.   
     
     
         2 . The chainring structure of  claim 1 , wherein the torque-transmitting coupling is configured to transmit substantially all of the torque applied to the chainring structure from the crank arm. 
     
     
         3 . The chainring structure of  claim 1 , wherein the pairing feature is configured to position the chainring structure on the crank arm; 
     
     
         4 . The chainring structure of  claim 1 , wherein the chainring structure comprises a chainring carrier and a separate chainring. 
     
     
         5 . The chainring structure of  claim 1 , wherein the chainring structure includes power meter elements. 
     
     
         6 . The chainring structure of  claim 1 , wherein the torque-transmitting coupling provides a substantially uniform load transfer between the chainring structure and the crank arm. 
     
     
         7 . The chainring structure of  claim 1 , wherein the pairing feature is defined by eight (“8”) lobes extending radially inward. 
     
     
         8 . The chainring structure of  claim 1 , wherein each lobe includes a single chainring hole of the plurality of chainring holes. 
     
     
         9 . The chainring structure of  claim 1 , wherein at least two of the chainring holes include an angled section; and the chainring structure further comprising:
 a plurality of fasteners, at least two of the plurality of fasteners having an fastener alignment feature formed thereon to cooperate with the corresponding angled section of the chainring carrier holes to align and connect the chainring structure on the crank arm.   
     
     
         10 . The chainring structure of  claim 9 , wherein the angled section is formed midway along two or more of the plurality of chainring holes. 
     
     
         11 . The chainring structure of  claim 10 , wherein at least two of the fasteners include a head portion and a threaded portion that are formed on opposite sides of the fastener alignment feature. 
     
     
         12 . The chainring structure of  claim 11 , wherein at least two of the carrier holes includes a straight-sided first section and a straight-sided second section flanking the angled section, the first section being wider than the second section. 
     
     
         13 . The chainring structure of  claim 9 , wherein the alignment features and the angled sections are both tapered and wherein each forms an angle of 90 degrees. 
     
     
         14 . The chainring structure of  claim 1 , wherein the radially interior profile of the chainring structure is sized and shaped to be arranged in a predetermined rotational position relative to an exterior profile of a post portion of the crank arm. 
     
     
         15 . The chainring structure of  claim 14 , wherein the exterior profile of the post includes a key that positions the chainring carrier on the crank arm in the predetermined rotational position. 
     
     
         16 . The chainring structure of  claim 15 , wherein the plurality of chainring holes is disposed on a bore circle diameter. 
     
     
         17 . The chainring structure of  claim 16 , wherein a majority of the radially inward extending lobes include a vacant space between particular lobes that extends radially inward of the bore circle diameter, and at least one alignment vacant space between other lobes extends to a point radially outward of the bore circle diameter at the radially innermost extent of the alignment vacant space.