Bicycle propulsion system for electric bicycle conversion

Abstract

A bicycle propulsion system including a concentric rotor assembly and a chassis assembly. The concentric rotor assembly: defines an outer drive surface; defines an inner retention surface; includes a set of sprocket brackets arranged about the inner retention surface of the concentric rotor assembly and configured to engage with teeth of a bicycle sprocket; and is configured to engage around the bicycle sprocket, wherein a center axis of the outer drive surface is concentric with a rotational axis of the bicycle sprocket. The chassis assembly: is configured to secure to a stay of the bicycle; includes a retention subassembly configured to translationally constrain the concentric rotor assembly relative to the chassis assembly; includes a drive subassembly configured to engage the outer drive surface of the concentric rotor assembly; and includes a motor configured to rotate the concentric rotor assembly via the drive subassembly.

I claim: 
     
         1 . A bicycle propulsion system comprising:
 an annular rotor assembly:
 operable in an open configuration and a closed configuration; and 
 comprising:
 a first rotor element; 
 a second rotor element cooperating with the first rotor element to form a circular outer drive surface around a first bicycle sprocket in the closed configuration; 
 a first sprocket bracket extending inwardly from the first rotor element and configured to engage the first bicycle sprocket in the closed configuration; and 
 a second sprocket bracket extending inwardly from the second rotor element and configured to engage the first bicycle sprocket in the closed configuration; and 
 
   a chassis assembly:
 configured to transiently couple to a frame element of a bicycle; 
 comprising a motor; and 
 comprising a drive subassembly configured to transfer torque output by the motor into the circular outer drive surface, formed by the first rotor element and the second rotor element in the closed configuration, to rotate the first bicycle sprocket via the first sprocket bracket and the second sprocket bracket.