U.S. patent number RE33,295 [Application Number 07/045,052] was granted by the patent office on 1990-08-14 for bicycle frame.
This patent grant is currently assigned to Trimble Design, Inc.. Invention is credited to James L. Trimble.
United States Patent |
RE33,295 |
Trimble |
August 14, 1990 |
Bicycle frame
Abstract
A bicycle frame where the structural support is provided by a
formed, stressed skin in conjunction with integral tubes and
stiffening ribs. A body is formed which joins front fork, pedal
axle, seat post and rear wheel axle. The body is visually solid
from the side--the two open triangles of a conventional tube frame
being filled in, and is airfoil shaped from the top. The body has
an integral rear fender where the rear wheel penetrates the rear
triangle, and assymetrical rear forks in place of conventional rear
frame stays. All control cables, and a cargo compartment, are
contained within the frame.
Inventors: |
Trimble; James L. (Natick,
MA) |
Assignee: |
Trimble Design, Inc. (Natick,
MA)
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Family
ID: |
26722324 |
Appl.
No.: |
07/045,052 |
Filed: |
April 30, 1987 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
508880 |
Jun 28, 1983 |
04513986 |
Apr 30, 1985 |
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Current U.S.
Class: |
280/281.1;
264/258 |
Current CPC
Class: |
B62K
3/02 (20130101); B62K 19/02 (20130101) |
Current International
Class: |
B62K
19/00 (20060101); B62K 19/02 (20060101); B62K
3/02 (20060101); B62K 3/00 (20060101); B62K
003/02 (); B62K 019/02 () |
Field of
Search: |
;280/281.1,281B,288,261,236 ;296/31P |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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950982 |
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Oct 1956 |
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DE |
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8822 |
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Dec 1896 |
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SE |
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3568 |
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1894 |
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GB |
|
1361394 |
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Jul 1974 |
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GB |
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Other References
"Tool Tests", Popular Mechanics, Sep., 1986; pp. 46-48. .
"Graphite USA", Bike Tech, Apr. 1987, p. 11. .
Winning Bicycle Racing Illustrated, May 1987, p. 33..
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Primary Examiner: Hill; Mitchell J.
Attorney, Agent or Firm: Fish & Richardson
Claims
What is claimed is:
1. A bicycle frame comprising, in combination, a tubular steering
support column formed to rotatably support a handle bar stem and
front fork and wheel assembly; a tubular seat support column formed
to support a seat post and seat assembly; a tubular pedal axle
support column formed to rotatably support a pedal crank and
chainwheel assembly; cantilever rear fork blades formed to support
a rear wheel assembly, the frame having the form of (1) an exterior
structural skin surface, connected to and extending between said
columns and rear fork blades in such a manner that the perimeter
edges of said skin define the outline of the frame's geometry from
the side view and an airfoil section with a blunt edge at the
steering support column, and a sharp edge at the seat support
column, and lower rear sides adjacent to the portion of the rear
wheel assembly which penetrates the frame's geometry arranged in
spaced apart substantially, parallel configuration positioned as
closely as possible to the rear wheel assembly, from the plan view,
(2) an internal arcuate fender, formed of structural skin, which
encloses the portion of the rear wheel assembly which penetrates
the frame's geometry, and fits within lower rear sides of said
exterior structural skin, and internal reinforcing means which, in
combination with said structural skin, form structural members
including, (3) tubular members connecting the steering support
column and seat support column, and the steering support column and
pedal axle support column formed by the addition of an elongate web
member secured in a substantially perpendicular manner between
opposing interior surfaces, and parallel to the perimeter edge of
said structural skin, (4) spaced apart, diverging, tubular members
connecting the pedal axle column and cantilever rear fork blades,
so arranged as to allow external routing of rear wheel drive chain
and external placement of rear wheel drive sprocket(s) and shifting
mechanism, formed by an integral outward extension of the lower
edge of said exterior structural skin forming top, outside, and
bottom surfaces secured to a separately formed inner surface by
flanges at the top and bottom, completing a substantially
rectangular tube section provided with the pedal axle column and
rear fork blade support means at respective ends; (5) elongate
reinforcing strips connecting rear, inner ends of said tubular rear
fork support members with said seat support column, and at an
intermediate position roughly bisecting said rear fender, with a
seat support web and connecting member, said reinforcing strips
filling a void space between said exterior structural skin and said
internal structural skin of fender, (6) an elongate web member
connecting seat support column and pedal axle support column
secured in a substantially perpendicular manner between opposing
inner surfaces of said structural skin, and (7) a web member
secured in a substantially perpendicular manner between opposing
inner surfaces of said structural skin, placed above and parallel
to a line connecting the pedal axle column and rear wheel axle, and
connected to the pedal axle support column by a vertical connecting
member.
2. A bicycle frame according to claim 1 wherein said structural
skin surfaces are constructed of any suitable moldable or formable
material or combination of materials.
3. A bicycle frame according to claim 1 wherein said tubular
connecting members are filled with a rigid expanded foam or
honeycomb core.
4. A bicycle frame according to claim 1 wherein perimeter edges of
said exterior structural skin, which define the frame's geometry,
are arranged in other than straight line configuration between
perimeter points in the side view and airfoil configuration in the
top view.
5. A bicycle frame according to claim 1 wherein said spaced apart
tubular members connecting the pedal axle column and cantilever
rear fork blades are offset horizontally from the longitudinal
frame centerline a required amount to place a rear wheel hub flange
assembly's centerline on the longitudinal frame centerline.
.Iadd.
6. In a bicycle frame having a steering support column formed to
rotatably support a handle bar stem and front fork and wheel
assembly; a seat support column formed to support a seat post and
seat assembly; a pedal axle support column formed to rotatably
support a pedal crank and chainwheel assembly; and a first
connecting member extending generally between said steering column
and said seat support column and defining an upper portion of the
frame outline, and a second connecting member extending generally
between said steering column and said pedal axle support column and
defining a front portion of the frame outline in side view;
the improvement wherein
said frame has an exterior skin surface extending generally between
said columns in such a manner that the perimeter edges of said skin
correspond to the outline of the frame geometry from the side view,
the skin of the frame defining an airfoil section when viewed from
above with a blunt leading edge at the front of the frame, and a
relatively sharper trailing edge at the rear of the frame adjacent
the seat support column. .Iaddend. .Iadd.
7. The bicycle frame of claim 6 wherein said exterior skin surface
is structural, and is united with internal reinforcing means,
forming a unitized body. .Iaddend. .Iadd.8. The bicycle frame of
claim 6 wherein said exterior skin surface extends rearwardly along
and close to a portion of the rear wheel. .Iaddend. .Iadd.9. The
bicycle frame of claim 6 or 8 wherein said frame further comprises
an integral arcuate fender. .Iaddend.
.Iadd.10. In a bicycle frame having a steering support column
formed to rotatably support a handle bar stem and front fork and
wheel assembly, a seat support column formed to support a seat post
and seat assembly, a pedal axis support column formed to rotatably
support a pedal crank and chainwheel assembly, and rear fork ends
formed to receive and support a rear wheel assembly,
the improvement wherein the frame generally terminates forward of
the rear wheel axle and said rear fork ends extend in cantilever
fashion rearwardly from said frame to and in a supporting
relationship with respect to said rear wheel axle,
said frame comprising a longitudinal structural member aligned with
and providing cantilever support to said rear fork ends, said
structural member supported vertically by a structural member
extending downwardly from the region of the seat, said longitudinal
structural member projecting laterally, at a right angle to the
direction of extent of the
fork ends, from said vertical support. .Iaddend. .Iadd.11. The
bicycle frame of claim 10 wherein said vertical support comprises
structural skin extending downwardly from the region of the seat,
the lower edge of said structural skin vertically supporting said
longitudinal structural member.
.Iaddend. .Iadd.12. The bicycle frame of claim 8, 10 or 11 further
comprising spaced apart, diverging, structural members connecting
the pedal axle column and cantilevered rear fork ends, adapted and
arranged to allow routing of the rear wheel drive chain and
placement of rear wheel drive sprocket(s) and shifting mechanism
external of the exterior skin
surface. .Iaddend. .Iadd.13. A bicycle frame according to claim 12
wherein said spaced apart structural members connecting the pedal
axle column and cantilevered rear fork blades are offset
horizontally from the longitudinal centerline of the frame in a
manner to enable the centerline of a rear wheel hub flange assembly
to lie on the longitudinal frame centerline while accomodating a
multispeed gear assembly on one side of
the wheel hub. .Iaddend. .Iadd.14. A unitary bicycle frame adapted
to perform the load-bearing functions of a conventional bicycle
frame having top tube means, seat tube means, down tube means, seat
stay means and chain stay means joined at load-bearing corners to
form main and rear triangles,
said unitary bicycle frame having, in side view, a generally
quadilateral shape, and formed of structural plastic skin extending
along the perimeter of said frame and across the load-bearing
corners of the frame, effectively forming structural tubular
members providing at least said top tube means and said down tube
means at edges of the frame. .Iaddend.
.Iadd.5. The bicycle frame of claim 14 wherein said structural
plastic skin extends substantially continuously from edge to edge
of said frame. .Iaddend. .Iadd.16. The bicycle frame of claim 14
wherein there in an
opening in the side of the frame. .Iaddend. .Iadd.17. A bicycle
frame having, in the region extending rearwardly from the seat
support and the pedal axle support of the frame, a structural skin
on both sides of the frame extending rearwardly to overlap a
forward portion of the rear wheel, and a structural section at the
lower edge of each side of said frame, extending along a line
projected from the pedal axle support to the rear wheel axle, said
structural sections being joined with respective sides of said
structural skin, said structural sections projecting laterally
outwardly from the skin, rearward ends of said sections being
constructed and spaced to support the rear wheel axle while, on
both sides of the frame, the trailing part of said skin lies closer
to the side of the wheel than does the respective support section,
thereby to obtain an aerodynamic streamlined effect. .Iaddend.
.Iadd.18. The bicycle frame of claim 17 wherein said structural
skin along each side of the rear wheel is disposed symmetrically
with respect to the centerline of the frame and said support
sections are asymmetrically disposed with respect to said
centerline, the section which extends outward further from said
centerline being shaped to support said rear wheel outwardly of a
multispeed gear assembly of the wheel, whereby said frame can
accomodate a wheel of uniform spoke tension, undished shape.
.Iaddend. .Iadd.19. The bicycle frame of claim 17 or 18 in which
the structural skin terminates at a point lying forward of the axle
of the rear wheel and a portion of each support section extends in
cantilever fashion rearwardly to support said rear wheel.
.Iaddend.
.Iadd. 0. The bicycle frame of claim 19 wherein said frame is
comprised
of two shells defining said structural skins. .Iaddend. .Iadd.21.
The bicycle frame of claim 19 wherein said structural skin and
structural sections are comprised of fiber reinforced resin and a
rigid insert member is anchored in said structural section and
extends therebeyond in said
cantilever portion. .Iaddend. .Iadd.22. The bicycle frame of claim
21 wherein said frame is comprised of two shells defining said
structural
skins. .Iaddend. .Iadd.23. In a bicycle frame, a unitized support
structure extending from the upper region of the frame at the seat,
downwardly to the region of the pedal axle, said support structure
comprising at least two spaced-apart transverse thin-walled
structural portions extending between and joined to structural side
skin portions, one of said transverse portions conforming to a
portion of the curvature of the periphery of the rear wheel and the
other transverse portion extending substantially straight from the
region of the seat to the region of the pedal axle. .Iaddend.
.Iadd.24. The bicycle frame of claim 23 wherein said structural
skins extend rearwardly from said curved portion to a line
extending from the seat region downwardly to the vicinity of the
rear wheel axle, said structural skins thereby enclosing a portion
of the rear wheel. .Iaddend. .Iadd.25. The bicycle frame of claim
23 or 24 wherein said structural skins extend forward of said
straight portion to cover at least part of the forward triangle
area of the frame and
terminating at the forward edge of the frame. .Iaddend. .Iadd.26.
The bicycle frame of claim 25 in which an arcuate fender is
unitized with said skins. .Iaddend. .Iadd.27. The bicycle frame of
claim 26 wherein said arcuate fender has integral structural side
skirts that terminate at the rear edge of the frame, said
structural side skirts lying inwardly of and generally parallel
with portions of the exterior structural skin of the frame and
being unitized therewith to define a strong structural section in
the region of the rear wheel. .Iaddend. .Iadd.28. The bicycle frame
of claim 22 wherein said strong structural sections closely
surround the rear
wheel. .Iaddend. .Iadd.29. The bicycle frame of claim 17, 18, 23 or
24 wherein said frame is comprised of two shells defining said
structural
skins. .Iaddend. .Iadd.30. The bicycle frame of claim 29 in which
an
arcuate fender is unitized with said skins. .Iaddend. .Iadd.31. The
bicycle frame of claim 30 wherein said arcuate fender has integral
structural side skirts that terminate at the rear edge of the
frame, said structural side skirts lying inwardly of and generally
parallel with portions of the exterior structural skin of the frame
and being unitized therewith to define a strong structural section
in the region of the rear wheel. .Iaddend. .Iadd.32. The bicycle
frame of claim 31 wherein said strong structural sections closely
surround the rear wheel. .Iaddend.
.Iadd.33. The bicycle frame of claim 6, 14, 17, 23 or 24 in which
an
arcuate fender is unitized with said skins. .Iaddend. .Iadd.34. The
bicycle frame of claim 33 wherein said arcuate fender has integral
structural side skirts that terminate at the rear edge of the
frame, said structural side skirts lying inwardly of and generally
parallel with portions of the exterior structural skin of the frame
and being unitized therewith to define a strong structural section
in the region of the rear wheel. .Iaddend. .Iadd.35. The bicycle
frame of claim 34 wherein said strong structural sections closely
surround the rear wheel. .Iaddend.
Description
FIELD OF THE INVENTION
The present invention is intended as an improvement on existing
high performance bicycles, both conventional tubular framed and
unitized panel framed. The frame incorporates new and unique
features which bring improvements in rigidity, ride, streamlining,
servicability, weight reduction, and appearance.
SUMMARY OF THE INVENTION
A monocoque bicycle frame where the structural support is provided
by a stressed skin, in conjunction with internal stiffening ribs. A
body is formed which joins the front fork, pedal axle, seat post,
and rear wheel.
The body is visually solid from the side--the two open triangles of
a conventional tube frame being filled in, and is airfoil shaped
from the top. The body has an integral rear fender where the rear
wheel penetrates the rear triangle, and rear forks in place of
conventional rear frame stays. All control cables, and a water
bladder, are contained within the frame. Internal stiffening is
accomplished with blocks at the rear forks' ends and bottom
bracket, shear webs or rigid foam forming "D" section tubes between
steering column and seat post, and steering column and pedal axle,
and reinforcing strips at the rear fork supports.
Design features of the frame include:
1. Low weight.
2. High torsional stiffness.
3. .[.Resiliant.]. .Iadd.Resilient .Iaddend.ride as the result of
cantilevered rear fork design:
Support for the rear wheel is provided by fork ends, of any
suitable material, with integral forward facing drop out slots and
derailleur mount boss, which are mounted into box section,
cantilever, rear forks. The top, outer side, and bottom surfaces of
the fork are formed integral with the frame body. The inner
completing surface of the box is formed in conjunction with the
integral rear fender. The rear forks are in the same location as
chain stays on a conventional tube frame, and at their forward end
encompass the bottom bracket support tube. No seat stays are
utilized, as on a conventional frame, vertical support being
provided by the integral construction of rear fork and frame body.
The sides of the rear body of the frame are kept as close as
possible to the rear wheel, with the rear fork flairing in width
the required amount for the rear hub axle width. This design
eliminates the problem, common on other unitized bicycle frame
designs, of the drive chain having to penetrate the frame side
wall. The rear forks cantilever approximately 3 inches from the end
of the frame body, and are designed to allow clearance for wheel
removal, free-wheel, sprockets, and chain line.
The cantilever of the rear fork ends allows a small amount of
.[.resiliance.]. .Iadd.resilience.Iaddend., which improves the ride
comfort over a conventional tube frame. The elimination of rear
seat stays also reduces aerodynamic drag.
4. Low wind resistance as the result of unitized design and
aerodynamic shape.
5. Improved rear wheel strength as the result of asymmetrical rear
fork design:
Because of the width of 6 and 7 speed freewheel clusters commonly
used on rear wheels of modern bicycles, it is necessary for the
rear hub flanges to be offset up to 7/16 inch from the center line
of the rear axle width. Conventional frames are built with
symmetrical rear chain stays. This results in an unbalanced or
"dished" wheel, which has much more tension on the sprocket side
spokes, in order to pull the rim into a centered position over the
rear axle. The rear fork of the monocoque bicycle frame is
constructed with an offset to the center line of the frame, of the
amount required to compensate for the offset of the rear hub
flanges, thereby allowing the rear rim to be perfectly centered
over the rear hub flanges. This results in balanced spoke tension
on each side of the wheel and a stronger wheel.
6. Internal waterbladder and cargo compartment for tools, spare
tire, food, etc.
7. Improved high speed stability as the result of frame side area
causing a fin effect and generating positive aerodynamic
stability.
8. Improved visibility resulting from greater surface area.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of a bicycle frame according to the
invention. Wheels being conventional in art are omitted for
clarity.
FIG. 2 is three horizontal sectional views of the frame in FIG. 1,
showing frame profile at different locations.
FIG. 3 is a rear elevation view of the bicycle frame in FIG. 1.
Componentry is omitted for clarity.
FIG. 4 is a plan view of the rear fork assembly, taken in section
directly above the fork, of the bicycle frame in FIG. 1.
FIG. 5 is a sectional view of one side of the rear fork assembly in
FIG. 4, at the fork end attachment.
FIG. 6 is a sectional view of one side of the rear fork assembly in
FIG. 4, indicating the tubular construction of the fork.
FIG. 7 is a sectional view of the rear fork supports of the bicycle
frame in FIG. 1.
FIG. 8 is a sectional view of the diagonal stiffening strips at the
rear fork of the bicycle frame in FIG. 1.
FIG. 9 is a sectional view of the vertical shear web, stiffening
strips of FIG. 8, and the integral rear fender of the bicycle frame
in FIG. 1.
FIG. 10 is a sectional view of the lower "D" section connecting
frame member of the bicycle frame in FIG. 1.
FIG. 11 is a sectional view of the seat post support and securing
system of the bicycle frame in FIG. 1.
FIG. 12 is a sectional view of the upper "D" sectional connecting
frame member of the bicycle frame in FIG. 1.
FIG. 13 is a sectional view of the steering support column of the
bicycle frame in FIG. 1.
FIG. 14 is a sectional view of the upper "D" section connecting
frame member, at the shift lever recesses, of the bicycle frame in
FIG. 1.
FIG. 15 is a vertical sectional view of the pedal axle support tube
and associated reinforcing of the bicycle frame in FIG. 1.
FIG. 16 is a horizontal sectional view of the pedal axle support
tube and associated reinforcing of the bicycle frame in FIG. 1.
DETAILED DESCRIPTION
A bicycle frame constructed in accordance with this invention is
illustrated in FIG. 1. The basic components of the frame include
the stressed skin frame shell, indicated by items 41 and 57, with
integral rear fender 40, and various internal stiffening shear
webs, strips and blocks, indicated by items 46, 47, 49, 54, 55, and
56. The frame shell may be formed on any suitable stiff,
lightweight material. Fiber reinforced plastic, of the many
available types and resin combinations, is suitable, as is light
weight sheet metal. In the case of fiber reinforced plastic, the
thickness and direction of fiber can be optimized in relation to
the stresses experienced at a particular location. For instance,
the side walls of the box section rear fork, FIG. 6, are more
highly stressed than the filler panels 57, and therefore can be
formed several layers thicker. The frame shell is most practically
manufactured in three pieces, a right and left half shell, and a
one piece rear fender. The pieces can be joined by any suitable
means, mechanically or adhesively. An integral joining tape 51, is
illustrated in FIGS. 12 and 14 as an example. The shear webs,
strips and blocks 46, 47, 49, 54, 55, and 56 can be formed of any
suitable material such as aircraft plywood, fiber reinforced
plastic, spruce or balsa wood, sheet metal, or rigid foam. The "D"
section tubes, FIGS. 10 and 12, provide the main structural support
of the upper frame, with the integral filler panels, item 57, FIGS.
1 and 2, providing additional bracing and streamlining. The box
section rear fork tubes, FIGS. 5 and 6, provide the main structural
support of the rear wheel axle, with additional vertical and
torsional support provided by strips 46 and 47 and reinforcing
block 55.
The frame includes a tubular steering support column, FIG. 13,
which supports a conventional front fork and brake assembly 28,
headset bearings 27, and handle bar and stem assembly 26. The tube
is of any suitable material, and is adhesively secured with a
hardening putty 42, and any suitable reinforcing material 53,
within the frame shell 41.
A recess is formed in the frame shell, FIG. 14, to accommodate gear
shift levers 25. Shift cables are routed internally to appropriate
shift mechanisms.
A tubular "D" shaped connecting member, FIG. 12, is formed between
steering column and seat post by the addition of a shear web 49,
and triangular reinforcing 48, between the frame shells 41. A
suitable joining material 51, joins the frame shells which are most
practically formed in halves. Rigid expanding plastic foam may be
used, filling the "D" tube, in lieu of, or in conjunction with,
shear web 49.
A recessed exit for the rear brake cable 23 is provided. The cable
runs internally within the frame tube, FIG. 12.
A tubular seat support columns, FIG. 11, which supports a seat post
and seat 22, is adhesively secured between frame shells 41, with a
hardening putty 42. The support column 52, is formed or molded of
any suitable material for a sliding fit around seat post 22. Seat
post is of existing art, and may be oval as illustrated, or
circular. A locking set screw and nut 21, are provided to secure
seat post at desired height. The bottom end of support column 52
rests on, and is joined to, a shear web 49, extending between sides
of frame shell 41.
A rear brake of conventional art is secured with a bolt to a
reinforcing plate of any suitable material .[.21.].
.Iadd.20.Iaddend., adhesively secured within frame shells with
hardening putty 42.
A strip of any suitable reinforcing material 46, is adhesively
secured between frame shell 41, and rear fender 40, to provide
stiffening for rear fork supports, FIG. 7.
A diagonal strip of any suitable reinforcing material 47, is
adhesively secured between frame shell 41 and rear fender 40, FIG.
8, to provide additional support for rear fork.
FIG. 9 illustrates a shear web 49, and reinforcing angles 48, which
connect seat support column 52, and pedal axle reinforcing block
55. FIG. 9 also illustrates the termination of reinforcing strips
47 and their joining block 50.
An access hatch 24, is provided within filler panels 57, for access
to cargo compartment formed within frame by shear webs 49.
A tubular "D" shaped connecting member, FIG. 10, is formed between
steering column and pedal axle as described for FIG. 12.
A front derailleur assembly 31, is set in a recessed pocket formed
in frame shell 41, and secured with screws to a reinforcing plate
of any suitable material adhesively applied to frame shell 41.
Control cables to this and rear derailleur are contained within
frame.
A tubular pedal axle support column 18, FIGS. 15 and 16, supports a
conventional bottom bracket assembly and crankset 36. The tube is
of any suitable material, and is adhesively secured with hardening
putty 42, and reinforced with shear webs 54 and 56, and pedal axle
reinforcing block 55.
A tubular rear fork, illustrated in plan in FIG. 4, connects pedal
axle with rear wheel axle. The rear fork can be asymmetrically
positioned with respect to frame center line, besst seen in FIGS. 3
and 4, to eliminate the necessity of dishing multispeed rear wheel
hubs 34, thereby eliminating uneven spoke tension in the wheel
assembly. FIG. 5 is a section view through one side of the rear
fork at the attachment point for cantilevered rear fork ends 19.
The fork ends can be constructed of any suitable material and are
formed with integral wheel drop-out slots and rear derailleur mount
boss. The fork ends are secured within the tubular fork with
hardening putty 42, reinforcing block or spacer of any suitable
material 43, and mechanical fasteners 45. An inner completing
surface 39, of comparable material and thickness, is attached to
frame shell 41, before installation of rear fender 40, thus forming
a box section tube of great rigidity. FIG. 6 illustrates the
configuration of the fork tube at a station closer to the pedal
axle. The drive side fork tube is indented, FIG. 4, item 36, to
provide clearance for chainwheel assembly 30. A typical chainline
is indicated by 35. The profile of the upper frame body is
indicated by 37, the tire/rim assembly by 38. The exit point for
the rear derailleur shift cable is indicated on FIG. 1 by item 33,
the rear derailleur, conventional in art, by 32.
* * * * *