Automatic bicycle shifter and electrical derailleur

1. An electrically powered bicycle drive chain derailleur apparatus comprising:

a) a four-bar linkage including a predominantly laterally stationary first member pivotally adjoining a second and a third bifurcating members of predominantly equal pitch with opposite ends thereof pivotally adjoining a fourth member of predominantly equal pitch to said first member,

b) said fourth member including a connection with a slaved bicycle drive chain caging assembly,

c) said first member including a fixed connection with a gearmotor housing with output shaft thereof including a fixed connection with pivoting center of said pivotally adjoining bifurcating second member at said first member, and

d) an electronic rotary encoder with sensing element thereof including an affixed connection to a motor armature of said gearmotor such that the sensing element serves to provide a position of said derailleur through direct sensing of a position of said motor armature, whereby

rotation of said output shaft of said gearmotor results in pivotal motion of said second member about said first member thereby forcing sheer lateral translation of said fourth member with said third member controlling rotation thereof, and consequently sheer lateral translation of said bicycle drive chain caging assembly.

2. The electrically powered bicycle drive chain derailleur apparatus of claim 1 wherein opposite ends of said second member and said third member including connections with opposite hook ends of an extension spring.

3. The electrically powered bicycle drive chain derailleur apparatus of claim 1 wherein said first member includes a rotatably operable connection with an affixing means to frame of a bicycle and is energized in the clockwise direction under the action of a first spring.

4. The electrically powered bicycle drive chain derailleur apparatus of claim 3 wherein said drive chain caging assembly includes two therein caged idler sprockets in constant engagement with said bicycle drive chain.

5. The electrically powered bicycle drive chain derailleur apparatus of claim 4 wherein said connection between said drive chain caging assembly and said fourth member is rotatably operable with said drive chain caging assembly energized in the clockwise direction under the action of a second spring.

6. The electrically powered bicycle drive chain derailleur apparatus of claim 1 wherein said housing of said gearmotor includes an affixed connection with housing of a multi-turn rotary potentiometer with a rotating sensing element shaft thereof including a fixed connection to an intermediate shaft affixed to an intermediate gear of said gearmotor.

7. The process of providing a bicycle drive chain electrical derailleur including:

a) providing a four-bar linkage with a predominantly stationary base,

b) providing a plurality of bifurcating member each further provided with a pivotally operable connections with said base,

c) providing a laterally translating member further provided with a plurality of pivotally operable connections to said plurality of bifurcating members,

d) providing a bicycle drive chain caging assembly further provided with an affixed actuation connection to said laterally translating member,

e) providing said base means with an affixed connection with a gearmotor housing provided with an output shaft including an actuation connection with a driving member of said plurality of bifurcating members, and

g) providing an electronic rotary encoder with sensing element thereof including an affixed connection to a motor armature of said gearmotor such that the sensing element serves to provide a position of said derailleur through direct sensing of a position of said motor armature, whereby

actuation of said gearmotor urges rotation of said driving member of said plurality of bifurcating members forcing lateral translation of said laterally translating member and thereof said bicycle drive chain caging assembly forcing lateral translation of said bicycle drive chain caging assembly with said lateral translation thereof being proportionately sensed by said electronic rotary encoder.

8. The process of providing a bicycle drive chain electrical derailleur of claim 7 wherein opposite ends of a pair of said plurality of bifurcating members are urged toward a collapsing state by opposite hook ends of an extension spring.