Note: Descriptions are shown in the official language in which they were submitted.
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STEERING BEARING ASSEMBLY FOR A BICYCLE
BACKGROUND OF THE lNV~NlION
1. FIELD OF THE INVENTION
The invention relates to a bicycle frame, more
particularly to a steering bearing assembly for
connecting a front wheel and handle bars to the bicycle
frame.
2. DESCRIPTION OF THE RELATED ART
A conventional steering bearing assembly is used to
connect a front fork wheel and handle bars to a bicycle
frame. The conventional steering bearing assembly
includes a head tube which is preferably welded to top
and down tubes of the bicycle frame, and a steerer
tube, one end of which is connected to a fork that
carries a front wheel and while the other end passes
through the head tube. After a tubular connector of a
stem is provided around the steerer tube so as to
dispose the same on the head tube, an adjuster nut is
placed on an upper end of the steerer tube to fasten
the connnector, the steerer tube and the head tube
together.
The above-mentioned steering bearing assembly is
advantageous, however, has a drawback. The internal
thread at the upper end of the steerer tube can wear
out due to constant vibration of the bicycle when in
operation or due to a long period of use. When
replacing the steerer tube, the user has to disassemble
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all the connecting parts, such as the stem, the head
tube or the like, thus inconveniencing the user.
SUMMARY OF THE INVENTION
A main objective of the present invention is to
provide a steering bearing assembly for a bicycle frame
which is easy to disassemble, thereby facilitating
replacement of a fastening member to fasten a steerer
tube and handle bars of the bicycle frame.
According to the present invention, the steering
bearing assembly includes a head tube connected
securely with a top tube and a down tube of a bicycle
frame, a steerer tube connected to a front wheel fork
and passing through the head tube, and a bearing
assembly provided at an upper end of the head tube.
The bearing assembly includes a lower race connected to
the head tube, an upper race connected to the steerer
tube, and a plurality of ball bearings enclosed between
the upper and lower races to permit relative rotation
of the two races. The upper race has an inner diameter
that is greater than an external diameter of the
steerer tube so that a clearance is formed between the
upper race and the steerer tube. A compression ring is
disposed in the clearance confined by the upper race
and the steerer tube. A mounting stem is disposed
above the compression ring and around the steerer tube.
The mounting stem is used for connecting the handle
bars of the bicycle frame to the steerer tube.
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A C-shaped resilient member is disposed inside the
steerer tube and is formed with an internal tapered
wall. A truncated cone-shaped inserter is inserted
into the tapered wall of the C-shaped resilient member
and is in contact with the tapered wall of the latter.
The inserter has an axially extending threaded bore
formed therethrough. A threaded bolt with a head is
disposed at an upper end of the steerer tube and
connects threadedly with the inserter in the threaded
bore of the latter. When the threaded bolt is
tightened, the inserter is squeezed into the resilient
member such that the latter expands radially to abut
frictionally against the steerer tube. The stem is
simultaneously forced downward by the head of the
threaded bolt so as to compress the compression ring
against the second race and the steerer tube in order
so as to retain the steerer tube vertically relative to
the bearing assembly.
In the event that the screw thread in the threaded
bore of the inserter wears out, the inserter can be
replaced easily by removing the threaded bolt from the
steerer tube. There is no need to remove the stem, the
head tube and the bearing assembly from the steerer
tube as required in the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present
invention will become more apparent in the following
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detailed description of the preferred embodiment with
reference to the accompanying drawings, in which:
Figure 1 shows a steering bearing assembly of U. S.
Pat. No. 5,095,770 which is used to connect handle
bars and a front fork wheel of a bicycle frame;
Figure 2 is an exploded view of the steering
bearing assembly shown in Figure 1;
Figure 3 is a partially cross sectional view of the
steering bearing assembly shown in Figure 1;
Figure 4 is a cross sectional view of the steering
bearing assembly shown in Figure 1;
Figure 5 is an exploded view of a steering bearing
assembly of the present invention which is to be used
to connect a front fork wheel and handle bars to a
bicycle frame; and
Figure 6 is a cross sectional view of the steering
bearing assembly of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figures 1 to 4, illustrate a steering bearing
assembly of a bicycle frame according to U. S. Pat. N0.
5, 095, 770 which is used to connect a front wheel and
handle bars to the bicycle frame. The steering bearing
assembly includes a steerer tube 33, one end of which
is connected to a fork assembly 31 that carries the
front wheel, a head tube 21 that is connected fixedly
to a top tube 19 and a down tube 23 of the bicycle, and
a stem 37 that carries the hand bars 15.
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The steerer tube 33 extends through the head tube
21 and through a tubular connector 35 of the stem 37.
In order for the steerer tube 33 to rotate relative to
the head tube 21, a lower bearing assembly 47 and an
upper bearing assembly 49 are mounted between the
steerer tube 33 and the head tube 21. The upper
bearing assembly 49 is located at an upper end of the
head tube 33 and includes a first race 57 and a second
race 59 which encase cooperatively a plurality of ball
bearings 61. The first and second races 57, 59 are
supported to rotate relative to each other by the ball
bearings 61. The first race 57 is fixedly connected
with the head tube 2lso that it rotates with the same.
The second race 59 has an inner diameter that is
greater than an outer diameter of the steerer tube 33
so that the steerer tube 33is carried by the upper
bearing assembly 49 with a clearance formed between the
second race 59 and the steerer tube 33. The second
race 59 has an annular contact face 63 which tapers at
an angle with respect to a longitudinal axis 65 of the
steerer tube 33.
An annular compression ring 67 with a gap 69 is
disposed above the second race 59 of the bearing
assembly 49. The compression ring 67 has an upper
surface 71 and a tapered contact surface 75 which
matches the contact face 63 of the second race 59 in
the bearing assembly 49.
2 1 1 3 3 3 3
When all of the elements are in place, an adjuster
nut 79 is threaded to an internally threaded upper end
77 of the steerer tube 33. At this stage, a head 83 of
the adjuster nut 79 contacts an upper end of the
tubular connector 35 and forces the latter downward on
the steerer tube 33. Longitudinal and radial forces
are exerted consequently on the compression ring 67
such that the latter is compressed against the steerer
tube 33 and the second race of the bearing assembly 49,
thereby locking the compression ring 67 in place on the
steerer tube 33.
Since the construction of a steering bearing
assembly of the present invention is generally similar
to the steering bearing assembly of U. S. Pat.
5,095,770, only the characterizing parts and components
which relate to the present invention will be described
in the following paragraphs.
Referring to Figures 5 and 6, the steering bearing
assembly of the present invention is characterized by
the compression member 60 and the fastening member.
The compression member 60 is a circular ring with a gap
62 and is easier to fabricate compared to the
conventional compression ring of the U. S. Patent
because it does not require a tapered contact surface.
The fastening member includes a threaded bolt 90, a C-
shaped resilient member 81 and a truncated cone-shaped
inserter 82. The threaded bolt 90 has an annular head
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91, a contact face 92 and a threaded shank 100 which
extends detachably from the annular head 91. The C-
shaped resilient member 81 has a knurled external
surface 811 and an inner tapered wall 813. The
truncated cone-shaped inserter 82 has an axially
extending threaded bore 822 formed therethrough. The
steerer tube 20 is secured relative to the head tube 10
for relative rotational movement. It will be
appreciated that the head tube 10 is typically welded
to the bicycle frame members 24 and 25. There is
provided a lower bearing assembly 29 and an upper
bearing assembly 50 between the steerer tube 20 and the
head tube 10. The lower bearing assembly 29 has a
first race 30 and a second race 34. The first race 30
may be press fit into the lower end of the head tube
10, so that the first race 30 pivots with the head tube
10. The second race 34 of the lower bearing assembly
29 may be press fit into the steerer tube 20, so that
the second race 34 pivots with the steerer tube 20. A
plurality of ball bearing 30' is enclosed between the
first and second races 30 and 34, respectively.
Accordingly, the first and second races 30 and 34'
are supported to rotate relative to each other by ball
bearings 30'.
The upper bearing assembly 50 has an upper race 52
and a lower race 32 encasing a plurality of ball
bearings 52' which enable the races 52 and 32 to rotate
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relative to each other. The upper race 52 is of larger
inner diameter than the outer diameter of the steerer
tube 20. A compression member 60 and a fastening
member are employed to connect the upper race 52 to the
steerer tube 20. The lower race 32 is connected to the
head tube 10 by a press fit, for example.
An upper end of a steerer tube 20 which is
employed in the preferred embodiment is not threaded.
Therefore, a manufacturing step is reduced in the
process for manufacturing the steerer tube 20. In
assembly, the compression member 60 is disposed between
a clearance 11 which is cooperatively defined by an
upper race 52 of the bearing assembly 50 and the
steerer tube 20. The inserter 82 is placed in the
steerer tube 20, and the C-shaped resilient member 81
is press-fitted into the steerer tube 20 above the
inserter 82. The threaded bolt 90 is disposed at a
topmost end of the steerer tube 20 such that the
threaded shank 100 extends into the steerer tube 20 to
connect threadedly with the inserter in the threaded
bore 822 of the latter.
When the threaded shank 100 is tightened, the
inserter 82 is squeezed into the C-shaped resilient
member 81 and radially forces the tapered wall 813 of
the C-shaped resilient member 81 such that the latter
expands to abut frictionally against the steerer tube
20. A tubular connector 70 of the stem 78 which is
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disposed above the compression member 60 and is
compressed downward by the head 91 of the threaded bolt
90, thereby forcing the compression member 60 to abut
the steerer tube 20 and the upper race 52 of the
bearing assembly 50 so as to retain the steerer tube 20
rotatably and vertically relative to the head tube 10.
When the threads on the shank 100 and inside the
inserter 82 wear out in time, the inserter 82 and the
shank 100 can be easily replaced by removing the
threaded bolt 90 from the steerer tube 20. There is no
need to disassemble the tubular connector 70 and the
head tube 10 from the steerer tube 20. The objective
and feature of the present invention is accordingly
achieved.
While a preferred embodiment has been explained and
described, it will be apparent that many changes and
modifications can be made in the general construction
and arrangement of the present invention without
departing from the scope and spirit thereof.
Therefore, it is desired that the present invention be
not limited to the exact disclosure but only to the
extent of the appended claims.
