System and method for changing a bicycle transmission ratio of a bicycle transmission

A bicycle transmission ratio changing system comprising:

• a first transmission selectively operable according to one of at least two transmission ratios;
• a second transmission selectively operable according to one of at least two transmission ratios;
• wherein the first transmission is connected to the second transmission to form, together, a bicycle transmission which is operable according to a plurality of bicycle transmission ratios;
• and
• a control unit configured to receive a shift signal for upshifting or downshifting a bicycle transmission ratio to a next higher or next lower bicycle transmission ratio, and, in response to receiving the first shift signal, change the transmission ratio of the first transmission and/or change the transmission ratio of the second transmission so as to upshift or downshift the bicycle transmission ratio to the next higher or next lower bicycle transmission ratio,
• wherein the control unit is configured to upshift and/or downshift the bicycle transmission ratio to the next higher or next lower bicycle transmission ratio according to an upshift sequence through the bicycle transmission ratios, and/or a downshift sequence through the bicycle transmission ratios, and wherein the upshift sequence and/or downshift sequence includes synchronous shift steps and non-synchronous shift steps, wherein the non-synchronous upshift steps in the upshift sequence include maintaining the transmission ratio of the second transmission and upshifting the transmission ratio of the first transmission, and wherein the synchronous upshift steps in the upshift sequence include synchronously upshifting the transmission ratio of the second transmission and downshifting the transmission ratio of the first transmission, wherein, in the upshift sequence and/or in the downshift sequence, the transmission ratios of the second transmission are traversed in a descending or ascending order only,
• wherein the upshift sequence includes at least three synchronous shift steps, and/or the downshift sequence includes at least three synchronous shift steps.

A method for changing a bicycle transmission ratio of a bicycle transmission including a first transmission selectively operable according to one of N different transmission ratios, N being at least two;

• and a second transmission selectively operable according to one of M different transmission ratios, M being at least three, M being larger than N;
• wherein the first transmission is connected to the second transmission to form, together, a bicycle transmission which is operable according to a plurality of bicycle transmission ratios;
• the method including
• upshifting a bicycle transmission ratio to a next higher bicycle transmission ratio according to an upshift shift sequence and/or downshifting the bicycle transmission ratio to a next lower bicycle transmission ratio according to a downshift sequence, wherein the upshift sequence and/or the downshift sequence includes synchronous shift steps and non-synchronous shift steps, wherein the non-synchronous upshift steps in the upshift sequence include maintaining the transmission ratio of the second transmission and upshifting the transmission ratio of the first transmission, and wherein the synchronous upshift steps in the upshift sequence include synchronously upshifting the transmission ratio of the second transmission and downshifting the transmission ratio of the first transmission, wherein, in the upshift sequence and/or in the downshift sequence, the transmission ratios of the second transmission are traversed in a descending or ascending order only,
• wherein the upshift sequence includes at least the lower of N or M−1 synchronous shift steps, and/or the downshift sequence includes at least the lower of N or M−1 synchronous shift steps.