Apparatus for the control by a cable of speed change devices of articulated parallelogram type for bicycles and similar vehicles

Apparatus for the control by a cable of a speed change device comprising an articulated parallelogram including a fixed upper support, a laterally movable lower support and two parallel levers pivotably connected to the supports. A chain guide is secured to the lower support and is laterally movable therewith for derailing a chain on pinions of a free wheel cluster. The parallelogram is subject to an elastic member which deforms the parallelogram in one direction, the cable acting on the parallelogram to deform it in the other direction against the action of the elastic member. The sheath of the cable is secured to the upper support of the parallelogram and the cable itself is secured to the lower support of the parallelogram such that application of external force to the cable produces deformation of the parallelogram. The upper support has a projection which can be integral therewith or attached thereto for carrying the sheath stop and disposing the same in an offset position laterally in the direction of the free wheel cluster and vertically in the direction of the lower support. The projection can have a groove in which the cable is received.

FIELD OF THE INVENTION 
The invention relates to an apparatus for the control by means of a cable 
of speed change devices of the articulated parallelogram type for bicycles 
and similar vehicles. 
The invention relates more particularly to the speed change devices which 
derail a chain for cycles and similar vehicles. 
PRIOR ART 
In a known speed change device of the type having an articulated 
parallelogram, as illustrated by way of example in FIG. 1 of the drawing, 
a chain guide 1 which derails a chain 2 on (FIGS. 9 and 10) pinions 3 of 
the free wheel cluster is transversely displaced by the deformations of an 
articulated parallelogram constituted by levers 4, 5, pivoted on a lower 
support 6 carrying a system of rollers and also on an upper support 7 
fixed to the bicycle. The control of the deformations of the articulated 
parallelogram is effected generally by a system having a cable 8 mounted 
at least partially in sheath 9. The cable is stressed or relaxed by acting 
on a control lever 12 to which the cable is secured. In one direction of 
control, normally to pass the chain on the pinions of increasing diameter, 
one or more elastic means R acting on the articulated parallelogram are 
placed under pressure. In the other direction, the elastic means acts by 
return action to move the chain on the pinions of decreasing diameter. 
The sheath 9 fixes the travel of the cable in order to effect the force of 
the control, at least in the path of the cable from the frame up to the 
speed change device. The extremity of the sheath 9 is supported in a 
sheath stop 10 mounted at a fixed point on the speed change device, 
generally, the upper support 7. The cable goes from this fixed point to an 
articulated element of the speed change device in order to apply the 
tension force exerted by the cyclist for the deformation of the 
parallelogram and, by consequence, the transverse displacement in the 
direction of arrow F in the direction of the pinions of increasing 
diameter. 
Most often, this force is poorly applied with respect to the desired 
transverse displacement F. The angle of the cable, and as a consequence 
the angle of application of the force with respect to the desired 
transverse displacement, is too large. Illustrated in FIG. 1 in the form 
of an angle .alpha. between a base, notably the line X--X, which 
establishes the angle of the cable and the direction of application of the 
force in a speed change device of known type. 
As a result, the control actions require more force, and are harder to 
apply, which does not facilitate the operations of speed change and the 
passage of the chain guide. 
As appears also from the schematic drawing in FIGS. 1, 2 and 3, the length 
of the displacement of the cable 8 which is necessary for the transverse 
displacement of the chain guide 1 from one extreme position to the other, 
is translated by the difference of the dimensions L and L 1. This 
difference is reduced, so that it provides a limited angular displacement 
.beta. of the control lever 12 to pass the speeds while engaging the 
chains successively with the pinions. This reduced angular displacement 
adversely affects the cyclist with regard to the position sought and the 
placement in correct position of the lever for each speed. 
Another significant disadvantage is found in the fact that, the transverse 
displacement of the chain guide 1 causes the angle of the cable and of 
application of the force to be constantly modified and irregular whereas 
there is produced a contact under great pressure of the cable in the 
sheath, notably at the outlet mouth of the sheath. This contact is a 
significant factor as regards wear and can have serious consequences. 
It has been proposed to transversely displace the sheath stop and 
consequently the position of the cable, with respect to the articulated 
parallelogram. However, this transverse displacement is limited by reason 
of the proximity of the free wheel cluster, and one can only therefore 
correct very slightly, the unfavorable angle of the cable and the 
application of the control force. Furthermore, even with a movable 
abutment, the orientation thereof remains fixed and the friction forces of 
the cable under high pressure (with the risks flowing therefrom) are not 
eliminated. Furthermore, in the position of the alignment of the chain 
guide 1 with the pinion with smallest diameter of the free wheel cluster, 
the sheath orients itself towards the free wheel cluster thereby risking 
contact therewith. 
SUMMARY OF THE INVENTION 
The control apparatus according to the invention overcomes these 
disadvantages by substantially reducing the angle of application of the 
control force formed between the cable and the direction of transverse 
displacement of the chain guide. In a manner no less important, this 
apparatus increases the length of displacement of the cable necessary for 
the same useful transverse displacement of the chain guide. Thereby, the 
angular displacement of the control lever acted on by the cyclist is 
greater and there is much greater smoothness of operation with better 
possibility of finding the speeds. 
The apparatus according to the invention is characterized in that the angle 
of the cable i.e. the angle of the application of the control force to 
deform the parallelogram and to transversely displace the chain guide is 
very substantially reduced by means providing a double offset of the point 
of departure of the cable in the direction of the exterior lever or other 
movable element of the parallelogram, this double offset being firstly 
laterally in the direction of the free wheel, cluster and secondly in the 
direction of the lower support.

DETAILED DESCRIPTION 
As regards what has been stated above, the speed change device with 
articulated parallelogram is only one embodiment of the application of the 
apparatus according to the invention and it is understood that other types 
of speed change devices can receive the apparatus according to the 
invention. 
In FIGS. 4, 5 and 6 there is seen a first embodiment of the apparatus for 
offset of the control cable which is constituted by a projection 7a on the 
support 7 extending in the direction of the free wheel cluster 3 and at 
the end of which is mounted a sheath stop 11 traversed by a cable 13 which 
is connected to a cable attachment 14 on the lower support 6 it is noted 
that between the extreme positions of the chain guide (FIGS. 4 and 5) the 
magnitude of the difference between La and Lb, the sheath stop 11 and the 
cable attachment 14 is greater than the difference between stated Land 
L.sup.1 in FIGS. 1 and 3; stated otherwise, the angular travel 
.alpha..sup.1 (FIG. 6) of the control lever 12 is substantially greater 
than .beta. in FIG. 3 and thus makes easier the finding of the passage of 
the speeds. Similarly, due to the offset laterally and towards the base of 
the sheath stop, i.e. the point of application of the force, the angle 
.alpha..sup.1 of application of this force is more acute as compared to 
the conventional control illustrated in FIG. 1 which permits a more 
efficient and rational traction of the chain guide 1. 
This position of the point of application of the force realized according 
to FIGS. 4 and 5 can be adjusted towards the base and towards the free 
wheel cluster as shown in FIG. 7 where the projection 7a on the upper 
support is provided with an oblong slot 76 permitting adjustment of the 
position sheath stop 11 fixed in orientable or non-orientable position. 
The slot 76 is inclined in the direction of the free wheel cluster and the 
direction of the lower support and can be curvilinear or rectilinear. 
According to another embodiment illustrated in FIGS. 8, 9, and 11, the 
sheath stop 15 comprises a shaft 15a threaded or rivetted to the upper 
support 7 and traversed by a hollow bolt 15b whose head receives the 
sheath 9 whereas the cable 16 traverses the sheath and the bolt 15b and is 
wound in a groove 17a formed in a member 17 of sector shape positioned to 
offset the cable on the side of the free wheel cluster before the cable 
descends for attachment either to the lower support 6 or in proximity to 
this support. It is not excluded in this embodiment for the sheath stop to 
be constructed in a different manner. 
In the illustrated embodiment, the member 17 is independent of the upper 
support to which it is connected by a threaded or rivetted pin 18, the 
member 17 being maintained angularly in the position for offset of the 
cable passing in the groove 17a by bearing of a concave surface 17b 
against the shaft 15a of the sheath stop mounted orientably or not on the 
upper support 7. 
The member 17 can be rather elongated in the direction of the lower support 
and the free wheel cluster in order to further diminish the angle .alpha.' 
(as shown in chain dotted lines in FIG. 9). 
In another embodiment illustrated in FIG. 12, the member 17 is adjustably 
mounted on the support 7 through an oblong curved slot 17c sliding by 
receiving the shaft 18 and whose radius has, as its center, the axis of 
the shaft 15a of the sheath stop which in this case is necessarily mounted 
movably on the upper support 7. 
This arrangement permits the adjustment of the angular position of member 
17, and therefore the offset laterally, and towards the base of the cable. 
There is thus modified, for the same useful displacement of the chain 
guide, the necessary travel of the cable and consequently the angular 
displacement of the lever. This permits the following advantages: 
1. Adjustment and obtention of the maximum angular travel of the control 
lever as a function of the number of teeth of the free wheel cluster which 
facilitates finding the speeds. 
2. The possibility of utilizing a lever with a much larger diameter of 
winding drum for the cable which leads to a much greater curvature and to 
a better support of the cable. 
The member 17 is preferably made of a plastic material for example 
"Delrin". However, the member 17 can be made of a different material from 
the upper support. 
It is not excluded that the member for offset laterally and towards the 
base of the point of application of the force can be realized from a one 
piece element integral with the upper support even if the sheath stop and 
the offset member are made from the same material or even if the upper 
support, the offset member and the sheath stop are made from the same 
material. 
The following advantages are also emphasized 
Substantial angular travel of the control lever facilitating the finding of 
the speeds. 
Better application of the traction force on the chain guide by offset 
laterally and towards the base of the point of application of the force, 
permitting a more rational angle of application for the traction of the 
chain guide. 
Low amplitude of self-alignment of the sheath towards the large teeth, as 
the point of bearing of the cable is always in contact on the profile of 
the support in the case of the offset member of sector shape. 
The sheath at its location where it forms a loop is not displaced or is 
only slightly displaced either towards the exterior of the bicycle which 
avoids ultimate snagging or towards the interior so as not to be in 
contact with the chain or the free wheel cluster. 
The invention is not limited only to the disclosed embodiments; and in 
contrast, it embraces all variations if defined by the ammended claims.