Grip for a bicycle shift control device

A rotatable handgrip for a twist-grip shift control device includes a rotatable member and a flexible grip disposed over the rotatable member. One or more spaces are defined between an inner peripheral surface of the grip and an outer peripheral surface of the rotatable member so that the grip bends radially inwardly in response to pressure from a hand part (palm, finger, thumb, etc.) so as to generally conform to the hand part. The space may be formed by a recess formed on the inner peripheral surface of the grip, on the outer peripheral surface of the rotatable member, a combination of recesses on the grip and the rotatable member, or through some other structure.

BACKGROUND OF THE INVENTION 
The present invention is directed to bicycle shift control devices and, 
more particularly, to a grip for a twist-grip shift control device which 
conforms more closely to a rider's hand. 
Twist-grip shift control devices are sometimes used to control various 
types of bicycle transmissions. Examples of such devices are disclosed in 
JP 44-26571; U.S. Pat. Nos. 3,633,437; 4,900,291 and 5,197,927. Such 
devices typically include a generally annular rotatable member that is 
mounted around the bicycle handlebar coaxially with the handlebar axis, 
wherein rotation of the rotatable member with the palm of the hand 
controls the pulling and releasing of the transmission control cable. 
For reliable operation of twist-grip shift control devices, it is desirable 
to have adequate traction between the palm of the hand and the rotatable 
member. U.S. Pat. Nos. 5,564,316 and 5,584,213 discuss the use of nubs and 
elongated ribs on a flexible cover to increase the traction between the 
hand and the rotatable member. However, while such nubs and ribs may help 
improve traction, they also tend to jam into the rider's hand, thus 
creating pain and fatigue. 
SUMMARY OF THE INVENTION 
The present invention is directed to a rotatable member for a twist-grip 
shift control device wherein the grip portion of the rotatable member 
conforms closely to a rider's hand to increase traction between the palm 
of the hand and the rotatable member, but which significantly decreases 
the risk of pain and fatigue. In one embodiment of the present invention, 
a rotatable handgrip for a twist-grip shift control device includes a 
rotatable member and a flexible grip disposed over the rotatable member. 
One or more spaces are defined between an inner peripheral surface of the 
grip and an outer peripheral surface of the rotatable member so that the 
grip bends radially inwardly in response to pressure from a hand part 
(palm, finger, thumb, etc.) so as to generally conform to the hand part. 
The space may be formed by a recess formed on the inner peripheral surface 
of the grip, on the outer peripheral surface of the rotatable member, a 
combination of recesses on the grip and the rotatable member, or through 
some other means. A rotatable grip constructed according to the present 
invention increases traction between the palm of the hand and the 
rotatable grip without requiring ribs or nubs. However, the present 
invention also may be employed advantageously in a handgrip which uses 
ribs and nubs, because the space between the grip and the rotatable member 
allow the ribs and nubs to yield to the pressure of the rider's hand. 
This, in turn, reduces or eliminates the incidences of pain and fatigue.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
FIG. 1 is an oblique view of a particular embodiment of a twist-grip shift 
control device 10 according to the present invention mounted together with 
a brake lever assembly 9. As shown in FIG. 1, shift control device 10 
includes a housing 12 mounted around a handlebar 8, a rotatable handgrip 
16 structured for rotation around an axis X coaxial with handlebar 8, a 
pulley 21 for pulling and releasing an inner wire 11a that slides within 
an outer casing 11b of control cable 11, and a pulley retaining member 28 
for retaining pulley 21 to housing 12. Pulley retaining member 28 may 
include a framed opening 28a for selectively displaying a numeral disposed 
on pulley 21 indicating the currently selected gear. A motion transmitting 
mechanism (not shown) is disposed between rotatable handgrip 16 and pulley 
21 for transmitting rotation of handgrip 16 to pulley 21. The motion 
transmitting mechanism may be constructed, for example, according to 
copending U.S. patent application Ser. No. 08/854,520 filed May 13, 1997 
now U.S. Pat. No. 5,921,139 entitled "Bicycle Shift Control Device" by 
Takuro Yamane and incorporated herein by reference. Since the motion 
transmitting mechanism does not form a part of the present invention, a 
detailed description of that mechanism shall be omitted. 
Brake lever assembly 9 includes a brake lever 9a pivotably mounted to a 
brake lever bracket 9b which, in turn, is mounted around handlebar 8 in 
close proximity to (e.g., adjacent) housing 12 of shift control device 10. 
Brake lever 9a is connected to a brake control cable 9c for controlling a 
brake device in a conventional manner. 
As shown in FIGS. 2A, 2B, 3A, 3B and 4, handgrip 16 includes a rotatable 
member 50 and a flexible grip 54. As shown in FIGS. 2A and 2B, rotatable 
member 50 includes a generally cylindrical main body 56 having an outer 
peripheral surface 58; a generally frustoconical intermediate portion 62, 
and a larger generally cylindrical portion 66 which interfaces with the 
motion transmitting mechanism within housing 12. A plurality of grip 
engaging members in the form of ribs 70 elongated in the direction of the 
handlebar axis X extend radially outwardly from outer peripheral surface 
58 of main body 56. In this embodiment, ribs 70 are evenly spaced in the 
circumferential direction of outer peripheral surface 58. Each rib 
includes a pair of side surfaces 74 that extend from a side surface 82 of 
frustoconical portion 62 in the direction of the handlebar axis X, and a 
top surface 86 that inclines slightly radially inwardly from side surface 
82 of frustoconical portion 62 to a rib end surface 90 located at an 
intermediate portion of outer peripheral surface 58. The plurality of ribs 
70 define a corresponding plurality of valleys 94 disposed between each 
pair of adjacent ribs 70, where the bottom floor 92 of each valley 94 is 
formed by outer peripheral surface 58 of main body 56. In this embodiment, 
outer peripheral surface 58 has a constant radius of curvature R from 
handlebar axis X along its entire axial length so that outer peripheral 
surface 58 has the shape of a straight cylinder. As a result, the floor 92 
of each valley 94 likewise has a constant radius of curvature as shown in 
FIG. 2B. 
As shown in FIGS. 3A, 3B, and 4, flexible grip 54 snugly fits around outer 
peripheral surface 58 of rotatable member 50, and an outer peripheral 
surface 96 of grip 54 includes a plurality of gripping projections 98 to 
further facilitate traction between the rider's hand and grip 54 (and 
hence ) rotatable handgrip 16. The inner peripheral surface 100 of grip 54 
includes a plurality of rotatable member engaging recesses 104 that are 
evenly spaced in the circumferential direction of inner peripheral surface 
100. Each rotatable member engaging recess 104 is shaped for snugly 
fitting to a corresponding rib 70 so that grip 54 is nonrotatably secured 
to rotatable member 50. A plurality of recesses 108 disposed between 
spaced apart pairs of inner peripheral surface portions 109 likewise are 
evenly spaced along the inner peripheral surface of grip 54. Each recesses 
108 cooperates with a corresponding valley floor 92 for forming a 
plurality of spaces 110 as shown in FIG. 4. Inner peripheral surface 
portions 109 are disposed adjacent to their corresponding ribs 70 and 
contact both the rib 70 and the adjacent valley floor 92 to snugly fit 
grip 54 to rotatable member 50. 
FIG. 5 is a side cross sectional view of the rotatable member 50 and 
flexible grip 54 illustrating how the flexible grip 54 bends in response 
to a gripping force exerted by a hand. As shown in FIG. 5, a finger 120 
presses radially inwardly to firmly grasp rotatable grip 16. Because of 
the flexibility of grip 54, the portions of grip 54 disposed over spaces 
110 form dents 124 and 126 which conform to finger 120 in response to the 
radially inwardly directed pressure of finger 120. When further pressure 
is applied by finger 120, the portions of grip 54 disposed over spaces 110 
bend radially inwardly as shown in FIG. 5 for partially or substantially 
reducing the volume of the corresponding space 110. Because of this 
yielding nature of grip 54, dents 124 and 126 enhance the traction between 
the rider's hand and rotatable handgrip 16 by conforming more closely to 
the rider's hand. Also, there are no sharp edges jamming into the rider's 
hand as in the prior art rib/nub designs. Furthermore, the yielding nature 
of grip 54 also cushions the rider's hand to avoid the excessive pressures 
caused by prior art rib/nub designs, thus further reducing the risk of 
pain or fatigue. 
FIG. 6 is a side cross sectional view of an alternative embodiment of a 
rotatable handgrip 16A according to the present invention using a 
different rotatable member 50A and flexible grip 54A. In this embodiment, 
grip 54A includes a plurality of rotatable member engaging members 55A 
projecting radially inwardly from the inner peripheral surface 100A. 
Rotatable member 50A includes a plurality of grip engaging recesses 57A 
formed in outer peripheral surface 58A, wherein each rotatable member 
engaging member 55A is disposed in a corresponding grip engaging recess 
57A. A plurality of recesses 108A disposed between adjacent pairs of 
rotatable member engaging members 55A are evenly spaced along the inner 
peripheral surface 100A of grip 54A. Each recess 108A cooperates with a 
corresponding portion of the outer peripheral surface 58A of rotatable 
member 50A for forming a plurality of spaces 110A that function in the 
same manner as spaces 110 in the first embodiment. 
FIG. 7 is a side cross sectional view of another alternative embodiment of 
a rotatable handgrip 16B according to the present invention using a 
different rotatable member 50B and flexible grip 54B. As in the first 
embodiment, the rotatable member 50B includes a plurality of grip engaging 
members in the form of ribs 70B projecting radially outwardly from the 
outer peripheral surface 58B, the grip 54B includes a corresponding 
plurality of rotatable member engaging recess 104B, and each grip engaging 
member 70B is disposed in a corresponding rotatable member engaging recess 
104B. However, in this embodiment, grip 54B does not have recesses 
corresponding to recesses 108 in the first embodiment. Instead, a 
plurality of evenly spaced recesses 150 are formed in the outer peripheral 
surface 58B of rotatable member 50B. Each recess 150 cooperates with the 
inner peripheral surface 100B of grip 54B for forming a plurality of 
spaces 110B that function in the same manner as spaces 110 in the first 
embodiment. 
FIG. 8 is a side cross sectional view of another alternative embodiment of 
a rotatable handgrip 16C according to the present invention using a 
different rotatable member 50C and flexible grip 54C. In this embodiment, 
the grip 54C includes a plurality of rotatable member engaging members 55C 
projecting radially inwardly from the inner peripheral surface 100C, the 
rotatable member 50C includes a plurality of grip engaging recesses 57C 
formed in the outer peripheral surface 58C, and each rotatable member 
engaging member 55C is disposed in a corresponding grip engaging recess 
57C. A plurality of evenly spaced recesses 150C are formed in the outer 
peripheral surface 58C of rotatable member 50C. Each recess 150C 
cooperates with the inner peripheral surface 100C of grip 54C for forming 
a plurality of spaces 110C that function in the same manner as spaces 110 
in the first embodiment. 
While the above is a description of various embodiments of the present 
invention, further modifications may be employed without departing from 
the spirit and scope of the present invention. For example, the size, 
orientation, location and shape of the various components may be changed 
as desired. Material may be added or removed from the parts as well. Thus, 
the scope of the invention should not be limited by the specific 
structures disclosed. Instead, the true scope of the invention should be 
determined by the following claims. Of course, although labeling symbols 
are used in the claims in order to facilitate reference to the figures, 
the present invention is not intended to be limited to the constructions 
in the appended figures by such labeling.