Land vehicles: wheels and axles – Wheel – Tension wheel; e.g. – spoke
Patent
1992-03-10
1993-07-20
Stormer, Russell D.
Land vehicles: wheels and axles
Wheel
Tension wheel; e.g., spoke
301 95, B60B 104
Patent
active
052287564
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a bicycle rim for spoked bicycle rear wheels.
BACKGROUND OF THE INVENTION
A conventional bicycle rear wheel comprises a rear wheel hub to one side of which is fitted a set of sprockets for a driving chain. Hub flanges on either side of the hub are connected by wire spokes under tension with a conventional tire-carrying rim. The rear wheel rim is the same as is used on the front wheel of the bicycle in question.
The presence of the sprocket set in a conventional rear wheel leads to an undesired lateral displacement of the center plane of both hub flanges from the rim center plane toward the opposite side from the sprocket. As a result of this roughly 5 to 10 mm displacement, which is known as the amount of dish, the tension on the sprocket-side spokes is greater than that of the spokes on the side away from the sprocket to an extent which greatly reduces the stability of the rear wheel. This is the most important problem with bicycle rear wheels and it has been known for decades. It is therefore desirable to bring about an optimum balance of the spoke tensions on the two rear wheel sides.
French patent application 76 22859 solves this problem by a lateral displacement of the center plane of both hub flanges in rear wheels toward the sprocket side, the rim position in the center plane of the frame being retained. Both hub flanges are then at the same distance from the rim center plane and the spoke tensions on both wheel sides are therefore completely compensated, as is each bicycle front wheel. Wide use of this system has not hitherto been possible due to the necessarily complicated bicycle frame with an asymmetrical rear frame.
Recently, the press has disclosed new and very expensive carbon rims. In the rear wheel rim the high torsional rigidity of the rim profile permits anchoring of the spokes laterally displaced from the rim center toward the sprocket side, unlike the front wheel rim, in which there is conventionally symmetrical anchoring of the spokes. Thus, unlike the aforementioned solution, this measure with respect to the rear wheel only partly balances the unequal spoke tensions on both wheel sides. Nevertheless, a rear wheel equipped with such a rim can be used in any conventional symmetrical bicycle frame. However, it is a vital requirement for this solution that the rim be extremely stiff.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rim for a bicycle rear wheel which is made from standard, inexpensive material, but which can still withstand the increased stresses and loads associated with the lateral displacement of the spoke anchoring. This object is achieved with a rear wheel rim with laterally displaced rim holes for receiving spoke nipples and with an asymmetrical cross-section with respect to the rim center plane.
BRIEF DESCRIPTION OF THE DRAWINGS
The problem of the bicycle rear wheel using a conventional rim will be explained and then various embodiments of the invention will be described in detail with reference to the accompanying drawings wherein:
FIG. 1 is a transverse sectional view of a conventional bicycle rim with symmetrical spoke anchoring according to the prior art;
FIG. 2 is a transverse sectional view of the rim of FIG. 1, but with asymmetrical spoke anchoring according to the latest prior art;
FIG. 3 is an enlarged transverse sectional view of the rim of FIG. 2;
FIG. 4 is an enlarged transverse view similar to FIG. 3 but of a rim according to a first embodiment of the invention;
FIG. 5 is a schematic view of a complete, spoked rear wheel at a reduced scale with a rim according to FIG. 4 and having untensioned spokes;
FIG. 6 is a view similar to FIG. 5 but with tensioned spokes;
FIGS. 7-11 are transverse sectional views of additional embodiments of rims according to the invention, FIG. 11 being taken along the line I--I of FIG. 12;
FIG. 12 is a partial plan view of the inside of the rim of FIG. 11 as seen from the wheel axis; and
FIG. 13 is a transverse sectional view of a further embod
REFERENCES:
patent: 2937905 (1960-05-01), Altenburger
patent: 4531754 (1985-07-01), Engleman
Farley Walter C.
Stormer Russell D.
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