Abstract: A bicycle transmission mechanism including: a fixed housing having an annular cavity; a ratchet member attached to a wall of the annular cavity of the fixed housing; a locking member slidably disposed in the annular cavity of the fixed housing, the locking member being formed with a cord hole, a cord head of a steel cord being fitted in the cord hole, a cord body of the steel cord extending from the cord head out of the cord hole, the cord head and the cord body containing an angle, whereby the cord head provides a resilient force which makes a first end of the locking member always tend to deflect toward the ratchet member and engage therewith so as to one-way detent the locking member; and a rotary member having a projecting linking section for rotationally driving the locking member to wind/unwind the steel cord.

Abstract: A bicycle transmission control device includes a fixed housing fitted on a handlebar of the bicycle, one side of the housing being recessed to form an annular cavity in which a first locating section is disposed. A locking member having a first linking section and pivotably and slidably mounted in the annular cavity, one end of the locking member being formed with a second locating section, any end of the locking member being hooked with one end of the steel cord of the bicycle transmission system, the steel cord always resiliently pulling the locking member, whereby the second locating section is biased toward the first locating section to engage therewith. A rotary member fitted on the handlebar and pivotally mounted on outer side of the housing, a second linking section protruding from inner side of the rotary member for drivingly connecting with the first linking section of the locking member.