Gear shift device for bicycles

A gear shift device for a bicycle having a transmission chain, a first body for attachment to a bicycle frame, and a second body, pivotably associated to the first body, which selectively engages the transmission chain, the device comprising:

• an electric actuator mounted on the device that displaces the second body relative to the first body;
• and
• an absolute transducer separate and independent from the actuator and mounted on the device that detects an absolute position of the second body.

A gear shift device for bicycles having at least one derailleur, a first body attachable to a bicycle frame, and a second body that can be displaced with respect to the first body, which in turn causes engagement of a bicycle chain from one toothed crown to a toothed crown, the device comprising:

• an electric actuator that displaces the second body relative to the first body when it receives a gear shifting request, said displacement moving the chain from the one toothed crown to the second toothed crown;
• and
• a transducer separate and independent from the electric actuator that detects at least two positions of the second body relative to a position of the first body, wherein when one of said positions corresponds to a position where the chain is engaged with the second toothed crown, the transducer outputs a signal that selectively disables the electric actuator.

A gear shift device for bicycles having at least one derailleur, a first body attachable to a bicycle frame, and a second body that can be displaced with respect to the first body, which in turn causes engagement of a bicycle chain from one toothed crown to a toothed crown, the device comprising:

• an electric actuator that displaces the second body relative to the first body when it receives a gear shifting request, said displacement moving the chain from the one toothed crown to the second toothed crown;
• and
• a transducer that operates independently from the electric actuator and detects multiple positions of one of the first or second bodies relative to the other of the first or second bodies, wherein when one of said positions corresponds to a position where the chain is engaged with the second toothed crown, the transducer outputs a signal that selectively disables the electric actuator.

A gear shift device for bicycles having at least one derailleur, a first body attachable to a bicycle frame, and a second body that can be displaced with respect to the first body, which in turn causes engagement of a bicycle chain from one toothed crown to a toothed crown, the device comprising:

• an electric actuator that displaces the second body relative to the first body when it receives a gear shifting request, said displacement moving the chain from the one toothed crown to the second toothed crown;
• and
• an absolute transducer that operates independently from the electric actuator and detects at least two positions of the second body relative to a position of the first body.

A gear shift device for bicycles having at least one derailleur, a first body adapted to be attached to a bicycle frame, and a second body that can be displaced with respect to the first body to cause the selective engagement of a bicycle chain on a number of sprockets, to achieve the various gears of the device, the device comprising:

• an electric actuator for displacing the second body relative to the first body;
• and
• a transducer that operates independently and is separate from the electric actuator and is mounted on the device for detecting a position of the second body relative to a position of the first body, the transducer outputting a signal that selectively disables the electric actuator.

A gear shift device for a bicycle having a transmission chain, a first body for attachment to a bicycle frame, and a second body, pivotably associated to the first body, which selectively engages the transmission chain, the device comprising:

• an electric actuator mounted on the device that displaces the second body relative to the first body;
• and
• a transducer that operates independently from the electric actuator and is mounted on the device that detects a relative position of the second body with respect to the first body, wherein the transducer outputs a signal that selectively disables the electric actuator.

A gear shift device for bicycles having at least one derailleur, a first body adapted to be attached to a bicycle frame, and a second body that can be displaced with respect to the first body to cause the selective engagement of a bicycle chain on a number of sprockets, to achieve the various gears of the device, the device comprising:

• an electric actuator for displacing the second body relative to the first body;
• and
• an absolute transducer that operates independently from the electric actuator and is mounted on the device for detecting an absolute position of the second body, the transducer comprising two electric tracks and a contact with at least one point engaged in sliding contact respectively with the two tracks, wherein variation in the position of the contact gives rise to a variation in electrical resistance and produces a corresponding signal indicating the absolute position of the second body.

A gear shift device for bicycles having at least one derailleur, a first body adapted to be attached to a bicycle frame, and a second body that can be displaced with respect to the first body to cause the selective engagement of a bicycle chain on a number of sprockets, to achieve the various gear ratios of the device, the device comprising:

• an electric actuator for displacing the second body relative to the first body;
• and
• an absolute transducer separate and independent from the actuator, said transducer mounted on the device for detecting an absolute position of the second body.