Improvements in Back-forks of the Frames of Cycles.
Year: 1897

page_text: PROVISIONAL SPECIFICATION,
Improvements in Back-forks of the Frames of Cycles.
I, HAROLD FRANK LESLIE DIXON, of 55, Brownhill Road, Catford, London, S.E.,
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:
My invention relates to the construction of the back-forks or chain-stays of
cycle frames and has for its object certain improvements in the arrangement
and construction of the back-fork ends of a cycle frame whereby I am enabled
to obtain greater rigidity than in existing forms of those parts and also to
materially strengthen its resistance to the chain strain and the stress of riding.
In applying my invention to a cycle I propose to fix two tubes on the chain
side of the back forks instead of one as in existing constructions.
These two tubes are attached to the crank bracket one over the other and are
preferably run nearly parallel back to the back fork end where they are of
sufficient distance apart to admit of access to the back wheel axle nut.
The tubes are attached to the crank bracket by two lugs thereon preferably
equidistant from the centre of bracket into which they may be brazed in the
usual manner or attached to the ordinary form of bracket by means of suitable
fork-crown pattern plates of metal or a tubular lug brazed on. The back wheel
end of the tubes may be shaped to a D or other suitable section when and where
necessary for a narrow chain line and are united by a stiff vertical web formed of
a metal plate stamping or cast-lug furnished with a slot or opening to receive the
wheel axle in the usual manner.
t
These two tubes forming the chain side stay of the back forks may have any
section but I prefer to use tubes of a cylindrical section and to slightly D the
rear ends on the wheel side of the chain stay to give clearance where the metal
plate forming the web is bent round or riveted closely to the two tubes and the
whole securely brazed together forming the fork-end. This it does in such a
manner as to enable the back wheel axle to come between the two tubes forming
the chain stays the tubes themselves extending backwards beyond the back wheel
axle thereby keeping the great rigidity of the stays right. up to the back wheel
axle regardless of any chain adjustment varying the position of axle in the slot.
A suitable stamping, forging or cast-lug may be used in place of the metal
plate to form the web or fork end and where much greater strength is required
as for multicycles a third tube may be attached to the bracket by means of a lug
or crown plates as before mentioned and running central to and inside of the other
two tubes could be attached to the back fork end by a lug brazed on or any other
suitable means.
In this way I am enabled to greatly strengthen the frame without in any way
increasing the width of the bracket or hub.
1007

page_text: Improvements in Back-1orks of the Frames of Cycles.
I, HAROLD FRANK LESLIE DIXON, of 55, Brownhill Road, Catford, London, S.E.,
Electrical Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:
My invention relates to the construction of the back-forks or chain-stays of
cycle frames, and has for its object certain improvements in the arrangement
and construction of the back-fork-ends of a cycle frame whereby I am enabled
to obtain greater rigidity than in existing forms of those parts and also to
materially strengthen its resistance to the chain strain and the stress of riding.
In applying my invention to a cycle I propose to fix two tubes on the chain
side of the back-forks instead of one tube as in most existing constructions.
These two tubes are attached to the crank bracket one over the other and are
preferably run nearly parallel to the back-fork-end where they are of sufficient
distance apart to admit of access to the back wheel axle nut when made as shewn
in Fig. 1.
The twin stay-tubes (a, a, Fig. 1 & Fig. 2) are attached to the crank bracket
by two lugs thereon preferably equidistant from the centre of bracket into which
they may be brazed in the usual manner, or attached to the ordinary form of
bracket by means of suitable fork-crown pattern plates of metal (d Fig. 1 and
Fig. 2) or a tubular lug brazed on to the crank-bracket lug, or when bracket-lug
is not sufficiently long a short piece of tube (c Fig. 1) is brazed into it on to which
the three plates (d Fig. 1) or the tubular lug carrying the twin stay tubes are
brazed. The back-wheel end of the tubes may be shaped to a D or other suitable
section (ff Fig. 1) when and where necessary for a narrow chain-line, and the
tubes may be united by a stiff vertical web formed of a metal plate, stamping or.
cast lug furnished with a slot or opening to receive the wheel axle in the usual
manner (b Fig. 1).
Fig. 1 shews side elevation of twin chain-stay ready for attachment to an
ordinary form of bottom or crank bracket. Fig. 2 represents plan of same chain-
stay.
These two tubes forming the chain side stay of the back forks may have any
section but I prefer to use tubes of a cylindrical section and to slightly D the
rear ends (e e Fig. 1) on the wheel side of the chain stay to give clearance where
the metal plate forming the web is bent round or rivetted closely to the two tubes
and the whole securely brazed together forming the fork end. This it does in
such a manner as to enable the back-wheel-axle to come between the two tubes
forming the chain stays the tubes themselves extending backwards beyond the
back-wheel-axle thereby keeping the great rigidity of the stays right up to the
back-wheel-axle regardless of any chain adjustment varying the position of axle.
in the slot.
A suitable stamping, forging, or cast lug may be used in place of the metal
plate to form the web or fork-end, and this forged or cast lug may be of such a
shape that the two tubes come close together as they approach the back-wheel axle
and are brazed into the lug whose two tubular parts continue beyond the back-
wheel-axle, identical in principle with the continuation of the two tubes as pre-
viously described.
Where much greater strength is required as for multicycles
a third tube may be attached to the bracket by means of a lug or crown plates as
before mentioned and running central to and between the other two tubes could
be attached to the back fork end by a lug brazed on or any other suitable means.

page_text: In this way I am enabled to greatly strengthen the frame without in any way
increasing the width of the bracket or hub.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is:-
-
:-
(1) A tubular fork end in conjunction with a twin or duplex or double tube
chain-stay.
(2) Constructing the back fork end of a twin or duplex chain stay in such a
manner as to admit the back wheel axle to be always between a tubular extension
of the chain stay as Fig. 1.
(3) To attach a twin chain stay to an ordinary crank bracket by means of a
tubular lug, fork crown-pattern-plates or the like.
Dated this 11th day of May 1898.
HAROLD FRANK LESLIE DIXON.