A handlebar gear shifter for a bicycle includes a tabular handlebar having a support plate extending from an end of the handlebar at the top of the peripheral thereof. A sleeve is rotatably mounted to the handlebar. A fan-shaped mediate member has an end pivotally connected onto the support plate. A first cable has one end thereof engaged with a recess in the sleeve and the other end of the first cable is engaged with the mediate member. A second cable connects between the mediate member and a derailleur mechanism. A C-shaped member having notches is connected to the handlebar. A spring member is engaged with the sleeve. An index member is biased by the spring member and removably engaged with one of the notches. The improvement is that the distance between the pivot end of the fan-shaped mediate member and one distal end thereof connected to the first cable is approximately equal to or slightly less than that between the pivot end and the other distal end thereof connected to the second cable, so that the traveling distance of the first cable is less than that of the second cable. Therefore, the traveling distance of the first cable and thus the rotated angle of the sleeve can be shorted for each gearshift that is more convenient for operation.