An electronic shifting system for a bicycle (20, 54), comprising: a first shift unit (26, 58) including: a first brake support, a first brake lever pivotally mounted to the first brake support, and a first switch mechanism (27a, 48) mounted in or on the first brake support; a second shift unit (26, 60) including: a second brake support, the first and second brake supports configured to be mounted separately to a bicycle handlebar (22, 56), a second brake lever pivotally mounted to the second brake support, and a second switch mechanism (27b, 48) mounted in or on the second brake support; and a control unit (28, 128) in communication with and responsive to first and second signals from the first and second switch mechanisms (27a, 27b, 48), respectively, and characterised by the electronic shifting system wherein actuating the first switch mechanism (27a, 48) sends the first signal to the control unit (28, 128) which is configured, in response to the first signal, to send a first command signal to a rear gear shift mechanism (36, 136) to perform an upshift, and wherein actuating the second switch mechanism (27b, 48) sends the second signal to the control unit (28, 128) which is configured, in response to the second signal, to send a second command signal to the rear gear shift mechanism (36, 136) to perform a downshift, and wherein actuating the first switch mechanism (27a, 48) and second switch mechanism (27b, 48) concurrently sends the first and second signals to the control unit (28, 128) which is configured, in response to the first and second signals, to send a front shift command signal to a front gear shift mechanism (30, 130) to perform a front gear shift operation. a first shift unit (26, 58) including: a first brake support, a first brake lever pivotally mounted to the first brake support, and a first switch mechanism (27a, 48) mounted in or on the first brake support; a first brake support, a first brake lever pivotally mounted to the first brake support, and a first switch mechanism (27a, 48) mounted in or on the first brake support; a second shift unit (26, 60) including: a second brake support, the first and second brake supports configured to be mounted separately to a bicycle handlebar (22, 56), a second brake lever pivotally mounted to the second brake support, and a second switch mechanism (27b, 48) mounted in or on the second brake support; and a second brake support, the first and second brake supports configured to be mounted separately to a bicycle handlebar (22, 56), a second brake lever pivotally mounted to the second brake support, and a second switch mechanism (27b, 48) mounted in or on the second brake support; and a control unit (28, 128) in communication with and responsive to first and second signals from the first and second switch mechanisms (27a, 27b, 48), respectively, and characterised by the electronic shifting system wherein actuating the first switch mechanism (27a, 48) sends the first signal to the control unit (28, 128) which is configured, in response to the first signal, to send a first command signal to a rear gear shift mechanism (36, 136) to perform an upshift, and wherein actuating the second switch mechanism (27b, 48) sends the second signal to the control unit (28, 128) which is configured, in response to the second signal, to send a second command signal to the rear gear shift mechanism (36, 136) to perform a downshift, and wherein actuating the first switch mechanism (27a, 48) and second switch mechanism (27b, 48) concurrently sends the first and second signals to the control unit (28, 128) which is configured, in response to the first and second signals, to send a front shift command signal to a front gear shift mechanism (30, 130) to perform a front gear shift operation.