Improvements in Tandem Cycle Frames.
Year: 1896

page_text: Date of Application, 16th Sept., 1896-Accepted, 7th Nov., 1896
COMPLETE SPECIFICATION.
Improvements in Tandem Cycle Frames.
I, WILLIAM CROSS of 81 Jesmond Road, Newcastle-upon-Tyne in the County
of Northumberland, Civil 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:-
This invention relates to cycle frames particularly adapted for bicycles to carry
two ladies seated one behind the other. In order to give stiffness and rigidity to
compensate for the two drops in the frame, I provide a rhomboidal frame, having
its top and bottom members horizontal, but the top member longer than the
bottom one. The front and back crank axle bearings are carried on the end
members of the rhomboid so that the weight on the pedals will be transmitted
about equally to the two horizontal members.
The back end member is prolonged upwards and carries the back saddle, while
rods or tubes from the top of this continuation and from the back ends
respectively of the horizontal members to the back wheel axle make double
systems of triangulation for carrying the rear wheel axle.
The front end member of the rhomboidal frame is continued upwards and
connected to the bottom of the steering head, another tube or alignment of
3 tubes is carried from the bottom of the steering head to the back end of the
lower horizontal member of the rhomboid, thus forming another triangulation.
From the front end of the top horizontal member a tube or alignment of 2 tubes
is carried to the top of the steering head on the steering fork. From the front
end of. the bottom horizontal member a tube or alignment of two tubes is carried
upwards parallel to the steering head or substantially so aud to the back member
of the rhomboid and its continuation. This tube carries the front saddle and the
back handle bar, another tube or alignment of two tubes from the upper end of
this to the back end of the lower horizontal member completes the system of
triangulation. In making this frame the members of it may consist of one two
or more tubes or rods as may be considered best for their respective positions.
The connection of these tubes or rods may be made as is usually done at
present. This system may be applied to tricycles and other cycles and similarly
arranged for three or more riders if required. It also may be applied to cycle
autocars.
The annexed drawing illustrates the improved frame in a diagrammatic view
A B D C is the rhomboidal frame of which A B is parallel to and longer
than C. D. CA is produced to E and carries the back saddle; while E F, A F
and C F connect CE to the back wheel axle F. D. B. is continued to G where
it joins the bottom of the steering head which carries the steering fork H also B is
connected to J at the top of the steering head. DK carrying the front saddle
and back handle bar is made parallel to CE and JG while K. C. completes the
triangle K. D. C. Preferably I make F E. F A. F C. C D. D G C A DL
and A. B. each of two parallel tubes, although A. B. can be arranged satisfactorily
as a single tube. And I preferably make A E C K and L. K. of single tubes
and C G and BJ of three and two aligned tubes respectively. At FE. A C. N K.
L D. B M. J. G. the respective tubes or members are joined together by suitable
connections. The rear or back pedal crank axle P is carried by AC at an
intermediate point between A and C. and the front pedal crank axle R is carried
by D. B. at a point intermediate between D and B. In this system of framing it

page_text: is seen that the rhomboid A B D C imparts the stiffness and rigidity necessary to
compensate for the double drop while the series of triangles composing the frame
transmit the strains in such a manner that no one member of the frame is strained
disproportionately to the others.
Also the rhomboidal frame and its supports on the back and front wheels may
be considered as a girder strong enough to transmit the stresses to the wheels and
the extensions for saddles and handles as superstructures.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The combination of tubes or rods forming a tandem cycle frame substantially:
as described.
2. A tandem cycle frame consisting of a rhomboid combined with triangles
substantially as described.
3. In a tandem cycle frame the combination of a rhomboid and triangles, with
the pedal crank shaft axles carried on end members of the rhomboid thus
conveying the weight to the top and bottom members thereof.
4. A double drop tandem cycle frame stiffened and braced as described.
Dated this 16th day of September 1896.
HERBERT HADDAN & Co.,
18 Buckingham Street, Strand, London, W.C., Agents to Applicant.