Abstract: An easy-adjustment bicycle gear-shifting system consisting of a microcontroller unit, a memory, a driver and a derailleur is disclosed. The memory has stored therein more than three position tables each containing the position information of the derailleur relative to the chainrings. The position information contained in one position table has a part or all different from the position information contained in every other position table. The position tables are arranged one after another in a proper order corresponding to one same chainring in such a manner that every two adjacent position tables are differed by a distance value corresponding to one same chainring. The microcontroller unit selects one position table, and drives the driver to shift the derailleur to the corresponding position according to the position information of the selected position table.

Abstract: A speed indicator for a shifting device of bicycle. The speed indicator is operated by a shifting device which has an arresting face. The speed indicator includes a housing disposed on the bicycle handlebar and provided with a slide portion. A rotating member is pivoted with the housing and provided at one end with a first long hole and at other end with a second long hole. An actuation set is disposed slidably on the housing and provided with an urging rod urged by an elastic member to press against the arresting face of the shifting device. A guide pin is inserted into the first long hole of the rotating member. A display member is disposed slidably in the slide portion of the housing and provided with a guide pin which is inserted into the second long hole of the rotating member. As the shifting device is turned to shift gear, the arresting face urges the actuation set member.