DE9002082U1 - Connecting structure for coupling two bicycles to form a double bicycle with three wheels arranged one behind the other - Google Patents

Description

DESCRIPTION I Applicant: Tim Stoffregen

Title: Connecting structure for coupling two bicycles to form a double bicycle with three wheels arranged one behind the other.

The invention relates to a construction with the help of which two normal bicycles can be reversibly connected to form a double bicycle without great expenditure of time and material. In this way, users can enjoy a tandem-like riding experience without having to finance such an expensive special construction for the rather rare occasions of use. In most cases, this concerns purely leisure activities such as cycling trips on the shore or longer bike tours.

Status d.si Techniic:

There are a number of ways to connect two bicycles to form a tandem-like double bicycle. There are complex, welded constructions and constructions with screw connections. The individual bicycles are arranged one behind the other (usually with three wheels) or next to each other (i.e. with four wheels). An invention similar to the invention presented here in the arrangement of the individual bicycles is described in the published patent application DE 37 29 879. This is an adapter part that allows the attachment of a second bicycle with the front fork, without the front wheel, in such a way that a pivot point is created either on the rear axle or in the immediate vicinity of the rear axle of the front bicycle, which allows for unevenness in the road. (This wording was taken from the patent claim of the published patent application mentioned.)

Criticism of the state of the art:

Until now, it was possible to ride a bike with two people either on structures that did not allow for dismantling to make a single bike (conventional tandems and other welded special structures), or on structures that could be dismantled to make a single bike, but which left a lot to be desired in terms of practicality, stability and - associated with this - riding safety.

The above-mentioned construction, which is available as a disclosure document, has several obvious structural defects:

l.The connection to the front bike is only made via two points on the rear dropouts, i.e. on the bottom right and left near the rear axle.

This arrangement means that no frame structure is formed that could absorb torsional forces during driving or centrifugal forces during braking.

Particularly when both riders increase their pedaling power, the twisting of the two bicycle frames relative to each other will cause the overall construction to wobble.

2.As soon as the riders cause the bicycle frames to twist in relation to one another by pedaling, pulling on the handlebars and shifting their own weight, high forces will be exerted on the connection between the fork dropouts and the adapter part. The long lever formed by the front fork between the rear bicycle frame and the adapter part on the front bicycle frame will increase these forces even further. This can result in the fork dropouts, which usually have an open recess to accommodate the front axle, being able to tear out of the adapter part while the bike is in use.

3. Since the length of the front axle on bicycles is usually shorter than that of the rear axle, the front fork must be bent up to connect to the adapter part in order to achieve the same width as the rear dropouts. This difference in width cannot be easily bridged by the adapter part, as it would otherwise get into the area of the pinion (with hub gears) or the pinion (with derailleur gears) and would hinder their rotation and the sliding of the chain when pedaling.

Task:

The invention is based on the object of avoiding or eliminating the disadvantages listed above in the already known double bicycle designs and of developing a connecting construction that enables simple assembly to form a double bicycle and problem-free separation to form single bicycles and has a high level of practicality, stability and driving safety.

Solution:

This goal is achieved by the fact that the entire construction can be reversibly assembled using screw connections. By connecting the rear bicycle to three points of the front bicycle, a connecting frame is created that can absorb centrifugal and especially torsional forces and thus counteracts twisting of the entire construction. By shifting the pivot point between the two bicycle frames from the rear axle of the front bicycle to the vicinity of the steering bearing of the rear bicycle,

which is based on this adapter part. A preferred embodiment is characterized in claims 2 to 6. Description of an embodiment:

The drawings on pages 1 to 5 show the individual components of the connection structure in an exemplary embodiment.

Figure 1 shows a side view of a double bicycle connected by a connecting structure consisting of two individual bicycles, in order to illustrate the arrangement of the two individual bicycles and the position of the individual components of the connecting structure. Only the right strut (5) and the right double clamp (7) are shown and labeled in Figure 1. The corresponding counterparts on the left side have been omitted from the drawing.

The circled detail marked with A in Figure 1 is formed by the adapter part (1), which is shown in Figures 2 and 3 on Sheet 2 as a side view or sectional view (A-A). Here you can see how the adapter part (1) is attached to the ISO Gi (rear) rotated fork (13), near the steering bearing of the rear bicycle. This can be done by pushing it on from the dropouts of the fork (13) until the clamp-like linings on the adapter part (1) are lined with flexible material (14) (e.g. rubber or similar) so that the adapter part (1) fits tightly on the fork (13). A design with articulated clamps, the distance between which can be varied so that they can be adjusted to fork struts that are at different distances from each other on different types of bicycle, would also be conceivable. In both detailed drawings (Figures 2 and 3), parts of the connecting strut (2) and the left strut (4) or right strut (5) are also shown to illustrate their connection to the adapter part (1). The bolt (19) that fixes all three struts in an axis must be freely rotatable and dimensioned (at least 8 mm in diameter) so that all forces acting on this point can be absorbed. A ball bearing for this bolt, which serves as the axis of rotation, in the style of an encapsulated bicycle bottom bracket, is a good option. In contrast to these inner bearings, the protruding axle stumps would only have to have a round cross-section with an external thread in order to be able to fit the struts (4) and (5) and the connecting strut (2) that branches off in a fork shape at this end, which have been provided with corresponding holes at the ends, onto them and to secure them with lock nuts. Washers should be pushed onto the bolt (19) between the connecting strut (2) and strut (4) or (5).

Figure 4 on sheet 3 shows the detail that is circled in Figure 1 and marked with B. Here, the other end of the connecting strut (2) is shown with its approximate position in relation to the frame of the front bicycle (11), which is attached to the seat post clamp (3). Using an appropriate adapter sleeve (12) (made of plastic or similar), the inner diameter of the seat post clamp (3) can be adapted to the diameter of the seat post (10) (which varies on different bicycles). If the distance between the seat tube (10) of the front bicycle and the fork (13) of the rear bicycle is adjusted by moving the telescopically pushed tubes of the connecting strut (2),

they are held in position relative to one another by two locking screws (15) inserted through corresponding holes and secured with lock nuts. The length of the connecting strut (2) should be adjusted so that the connection point circled in Figure 1 and marked with A is as far above the rear axle of the front bicycle as possible. The struts (4) and (5) should be dimensioned in such a way that the same connection point is as close as possible to the rear tire of the front bicycle. Accordingly, the adapter part (1) which forms this connection point must be shaped so that the tire of the rear wheel can pass unhindered between the fork (13) of the rear bicycle. In this way, the rear wheel of the front bike will assume almost exactly the position that the (now removed) front wheel of the rear bike would normally assume. By loosening the handlebar cone before the 180 degree rotation of the fork (13) and tightening it after the rotation, the handlebar of the rear bike will retain its original position.

Figure 5 on sheet 4 shows the top view of the connecting strut (2) with the cross-section through the seat post (10) (section B-B; see Figure 4). Here you can see the forked end and the two tubes of the connecting strut (2) that slide into each other, as well as the connecting screw (17) with which the connecting strut (2) and the seat post clamp (3) are connected, secured by a lock nut.

On sheet 5, the detail marked C and circled in Figure 1 is shown once as a side view (Figure 6) and once as a top view (Figure 7). For a better overview, struts (4) and (5) have been drawn with cross hatching. The single hatched areas in Figure 7 represent the cross section through the two struts.

(4) and (5). Figure 6 shows only the right rear dropout (9) with the adjacent sections of the front bicycle frame, as well as the right double clamp (7) and right strut (5), while Figure 7 also shows the left rear dropout (8) of the front bicycle with the left double clamp (6) and left strut (4). In Figure 7, the dashed line rl 4 a iindafökra Lade He &tgr;- Hinterarhae Hob vapfjaren ■ — -.-- — -·. __~ _-. _o — - ·*-·--. ~ -*■—&ogr;—

The double clamps (6) and (7) are mounted near the rear dropouts (8) and (9) using eight screws each, which, secured by nuts, ensure a firm fit and good adaptation to the frame tubes in this area. The left strut (4) and the right strut

(5) is screwed to the double clamp (6) or (7) using a connecting screw (16). Since strong forces act on these two connection points (left and right), as well as on the first connection point (which is formed by the adapter part (1)), the connecting screws (16) should have a diameter of 8 mm and be secured with lock nuts.

Depending on the expected loads, the struts (4) and (5) should be made of steel tubes, while the connecting strut (2) can be made of aluminum tubes. The adapter part (1) and the seat post clamp (3) can also be made of aluminum. The double clamps (6) and (7) should be made of more resistant material (e.g. appropriately dimensioned

Duralumin sheets).
Achievable benefits:

Quick assembly and disassembly is possible without much effort. The seat post clamp (3) and the two double clamps (6) and (7) can remain on the front bike when used as a single bike. All that is needed is to loosen the connection formed by the connecting screw (17) between the seat post clamp (3) and the connecting strut (2), as well as the connections between the double clamps (6) or (7) and the struts (4) or (5) at the connecting screws (16) and pull the adapter part (1) off the fork (13) of the rear bike. By turning the fork (13) and locking the handlebars in the normal position, as well as mounting the front wheel and the front wheel brake, the rear bike is ready for use again.

The fork of the rear bike does not have to be bent open for assembly, instead it is simply turned 180 degrees and thus moves out of the area of the sprockets of the front bike. The connecting structure between the two bikes forms a torsion-resistant frame that counteracts any swaying during riding, caused by the two bike frames twisting relative to each other.

The coupling of two individual bicycles in this arrangement has advantages over a normal tandem. The forces of the two riders are transferred to separate drive wheels. The loads on the power-transmitting system (chain, chainrings and pinion) are therefore reduced by half compared to the loads on a conventional tandem. In addition, three braked wheels ensure better deceleration than the two on a tandem. The load on the wheels themselves is also naturally reduced compared to that on a tandem, as the weight of the two riders is distributed over an additional wheel.

When transporting in narrow stairwells, for example, and when parking in narrow rooms, the space can be used better thanks to the flexible connection.

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Claims (1)

Protection claims 1. Connection construction for coupling two bicycles to form a double bicycle with three wheels arranged one behind the other, characterized in that an adapter part (1) is attached to one end of a connecting strut (2) and a seat post clamp (3) is attached to the other end; that the adapter part (1) has clamp-like fork recesses which are lined with a flexible material (14); that the connecting strut (2) and the adapter part (1) are connected in an articulated manner by a bolt (19); and that a right and left strut (4 and 5, respectively) is attached to the adapter part (1), which have bicycle frame double clamps (6 and 7, respectively) at their respective dropouts (8 and 3, respectively) . . Connecting structure according to claim 1, characterized in that the connecting strut (2) is adjustable in length. . Connecting structure according to claim 1, characterized in that an adapter sleeve (12) is inserted into the seat post clamp (3). . Connecting structure according to claim 1, characterized in that the double clamps (6, 7) are screwed to the two struts (4, 5) via connecting screws (16).