Rotor system for a bicycle

A rotor system for a bicycle (1), for the purpose of bearing a fork (8) and transmitting the actuations of Bowden cables (31, 32), which each having a core (31a; 32a) includes first and second transmission elements (36, 37), that rotate relative to one another and are arranged in the area of the bearing (21, 23, 25) of the fork (8). The transmission elements include an annular region, mounted on a fork steerer (12) and surrounded by a head tube (21), and connection areas (36b; 37b) for the direct or indirect attachment of the rotor-side ends of the cores (31a 32a). At least one of the transmission elements (37) includes a connection area (37b) with a connecting element, which (32b) can be form-fittingly attached, interacting with, or being integrally connected to, the rotor side end of the core (32a) that is assigned with said at least one transmission elements (37).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application of International Application PCT/EP2013/052900 filed Feb. 13, 2013 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Applications DE 10 2012 103 465.6 filed Apr. 20, 2012 and DE 10 2012 111 204.5 filed Nov. 21, 2012, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a rotor system for a bicycle for the bearing of a fork and for the transmission of actuations of Bowden cables each having a core, with at least a first and a second transmission element which are rotatable relative to one another and which are arranged in the area of the bearing of the fork.

BACKGROUND OF THE INVENTION

From the DE 199 29 093 C2 a rotor system for a bicycle for bearing, rotatably by 360°, a fork and for the transmission of actuations of brake cables is known, with a rotor unit, arranged in the area of the bearing of the fork, which is movable on the whole relatively to the fork in axial direction and which comprises at least two transmission elements that are rotatable relative to one another, wherein the transmission elements at least in radial direction are surrounded by a housing.

Another rotor system, which also makes possible a 360° turn of the fork, is known from WO 2012/005610 A2. A first Bowden control cable is guided from the handlebar into the fork steerer. At the end of its core a bar is fixed, which protrudes out of the fork steerer through fork steerer openings, where it is taken up by the first transmission element. The arrangement of the core of the second Bowden cable leading to the back wheel at the upper ring-shaped second transmission element is done by means of a fixture bent at a right angle screwed onto the transmission element, in whose radially outwards extending area, which is provided with a slotted receiving opening for introducing the core, the thickened end of the core is suspended. At the housing a comparable overturned brake arm is screwed, which with its area extending outwards in radial direction, that is formed according to the above mentioned fixture, adheres to the first fixture from the bottom and supports it. This kind of arrangement also corresponds to the technical realization of DE 199 29 093 C2, in which the arrangement of the cores of the Bowden mechanisms serving as brake cables is only illustrated schematically.

In FR 571 408 a transmission mechanism is known, which uses bars and levers. In the stem a crank is mounted, at which a bar introduced into the fork steerer is articulated, which in the area of the lower end carries a bar that protrudes out of the fork steerer through fork steerer openings. A first transmission element sits on the bar. The second transmission element is formed bifurcated, with the shaft articulated at the transition from the head tube to the lower tube and resting with the fork peaks on the first transmission element. At the shaft of the second transmission element a Bowden control cable is fixed, which is guided further through the lower tube. The transmission elements do not form a unit, but perform different movements when a braking is executed.

SUMMARY OF THE INVENTION

The present invention is based on an object of improving a rotor system of the abovementioned type. In particular, the Bowden cable arrangement is to be simplified and the total rotor system is to be more economical to produce.

A bicycle, which is particularly designed as a BMX freestyle bicycle, comprises a rotor system according to the invention in order to avoid a twisting of the Bowden mechanisms serving as brake cables and in order to be able to actuate the rear wheel brake at any time. The bicycle, in particular when it is designed as a mountain bike, also can have a rotor system according to the invention for those Bowden cables, which serve as gear cables, in order to be able to operate the gear change at any time.

The two transmission elements form the essential components of a rotor unit of the rotor system according to the invention. A first Bowden cable of the provided Bowden cables is guided from the handlebar to the rotor unit and is in operative connection with the first transmission element. With the second transmission element, another Bowden cable of the provided Bowden cables is in operative connection, which is guided from the rotor unit to the rear wheel of the bicycle, in particular to a rear wheel brake or to a gear change. The two transmission elements cooperate in axial direction in order to transmit the actuation of the Bowden cables (more precisely that of the first Bowden cable on the second Bowden cable). The fork steerer defines the axial direction. For the direct or indirect arrangement of the cores of the Bowden cables at the transmission elements, the latter each comprise connection areas. The term “indirect” is to indicate the use of a separately formed and detachably mounted intermediate element, the term “direct” the absence of such an intermediate element. The term “detachable” is to indicate a separation possibility without destruction.

The connection area according to the invention in case of at least one of the transmission elements (preferably of the second transmission element) is arranged completely or almost completely inside the head tube (I. e. radially inside the head tube), thus does not protrude radially outwards, which facilitates the assembly. The fork steerer defines the radial direction. At this connection area a connecting element is form-fittingly attachable, the connecting element at least in axial direction directly interacting with the connection area. On the other hand, the connecting element cooperates with the rotor side end of the respective core (preferably of the second Bowden cable) detachably (and is formed separate from said end) or is connected in one piece with said end. This arrangement provides a simple, fast possibility of attaching the core at the transmission element. A tool, which hitherto was necessary for screwing the support of the end of the core, is no more necessary. Moreover, by the elimination of the screw, the number of parts can be reduced. Preferably, the connecting element at least partially embeds the rotor side end of the respective core. The end of the core can then be stretched (instead of forming a loop). In particular preferably the connecting element is molded directly at the core end, or cast onto it, or pressed onto it, or connected in one piece in another way, so that the number of parts can be further reduced.

For the attachment at the connection area, the connecting element may have a jut (guiding), which interacts with a guide groove of the second transmission element extending parallelly to the axis of the fork steerer (i.e. in axial direction). This jut of the connecting element can be for example cuboid or dovetailed. Alternatively, the connecting element comprises two juts, which under elastic deformation engage like a clip in undercut areas of the transmission element in the connection area, in which for the engagement an elastic deformation of the connecting element is provided. By the clipping a simple assembly is possible. One of the two juts preferably extends parallelly to the fork steerer axis and, from a front part of the transmission element, engages into a corresponding opening. The second of the juts is preferably, but not necessarily, perpendicular to it and engages in radial direction into a corresponding opening or deepening of the transmission element.

The two transmission elements have as basic form a cylinder ring, i.e. a sleeve, which allows a simple mounting. The two transmission elements can be arranged in alignment with each other (in axial direction in alignment with each other, i.e. axially one after the other) on the fork steerer, which requires the smallest radial installation space. However, they can also be concentric to one another (in radial direction concentric to one another, i.e. radially one inside another), i.e. the second transmission element—at least sectionally with respect to its axial extension—embeds the first transmission element (or vice versa), which allows a simple and defined mounting of the two transmission elements in relation to each other. The preferred mounting is a combination thereof, i.e. partially flush and partially concentric. For this purpose, the two transmission elements preferably comprise steps, by means of which they lie on top of each other. For all the mountings, there is a direct contact between the two transmission elements, preferably a sliding contact, for which purpose both transmission elements are preferably plastic injection molded parts. An intermediate ring, as it is used in the state of the art, can be omitted, so that the number of parts can be further reduced. With the same purpose preferably the connection area is formed one-piece on the second transmission element.

Preferably, the core of the first Bowden cable is introduced from the handlebar into the fork steerer, which exploits the already present installation space and saves installation space between fork steerer and head tube, thus allowing a particularly slim embodiment of the head tube. For the attachment of the core of the first Bowden cable at the first transmission element, preferably a bar is provided, which is mounted on the core, in the mounted state for example lies on a nipple or similar at the end of the core, and for the assembly is preferably tiltable relatively to the core. The bar protrudes through oblong-hole-formed fork steerer openings in radial direction out of the fork steerer (beyond the outside extension of the fork steerer), so that the first transmission element, which is mounted outside on the fork steerer, can be connected with the bar, for example set or pressed on it. Accordingly, the bar is introduced with its ends in seats, in particular openings or grooves, in order to cooperate form-fittingly and if necessary in force-locking manner with the first transmission element. For a connection with a (small) force-locking contribution the bar may engage into the first transmission element, for which purpose the bar (or the transmission element) comprises suitable catch noses, for example frontally.

The first Bowden cable with bar according to the invention and the second Bowden cable with connecting element according to the invention are preassembled components and can be sold separated from the bicycle or from the rotor unit as spare-parts or together with the rotor unit as kit of the rotor system.

In order to guide the core of the second Bowden cable, which by means of the connecting element is applied at the connection area of the second transmission element, to the rear wheel, the head tube, which bears the fork by means of headsets, has a—preferably oblong-hole-formed—head tube opening, by which the connecting element from the outside can engage into the head tube for the connection area at the second transmission element.

Preferably a third Bowden cable is provided, which is guided from the handlebar to the front wheel to a front brake. In order to guide, apart from the first Bowden cable, also this third Bowden cable through the fork steerer, the fixing device, which is provided for fastening the stem at the fork steerer, is modified accordingly. In the respective cap and the star grip nut placed in the fork steerer, or alternatively in the fixing screw to be screwed into the fork steerer, two openings or passages are provided, I. e. apart from the central passage known per se also an eccentric passage. Compared to an enlarged central passage, this conformation has the advantage that the seat of the star grip nut in the fork steerer is not weakened. The first Bowden cable, more precisely its core, is then introduced through the central passage, in order to catch if possible centrally at the bar. The third Bowden cable guided to the front brake is guided through the eccentric passage offset as to the known central passage.

In the following, the invention is explained more in detail on the basis of several embodiments represented in the drawing. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, a bicycle1indicated as a whole with1, which is designed as a BMX freestyle bicycle, comprises a frame3that at its rear end bears the rear wheel5of the bicycle1. At the front end of the frame3, a fork8is rotatably beared. At its lower end, the fork8bears the front wheel10of the bicycle1. On a fork steerer12forming the upper end of the fork8a stem14is fixed. The stem14comprises a horizontally extending handlebar seat16, which embeds the handlebar18of the bicycle1. The fork steerer12with its circular cylindrical symmetry defines the directions used in the following.

For bearing the fork8, the frame3has a generally circular cylindrical head tube21open on both faces, which is generally vertically oriented. The fork steerer12extending in axial direction is arranged, over a part of its length, inside the head tube21concentric with it. A lower headset23and a upper headset25consist of several components and can be twisted in themselves, each being mounted outside at the lower or upper end of the head tube21and inside on the fork8or its fork steerer12.

A rotor unit30described more in detail in the following is arranged inside the head tube21between the upper headset23and the lower headset21. The rotor unit30is displaceable by sliding in axial direction on the fork steerer12. An upper, first Bowden cable31is guided from a brake lever, merely suggested in the drawing, at the handlebar18to the rotor unit30, from which a lower, second Bowden cable32is guided along the frame3to a rear wheel brake at the rear wheel5not represented in the drawing. Accordingly, the first Bowden cable31(i. e. its core31a) comprises a handlebar side end and a rotor side end and the second Bowden cable32(i. e. its core32a) a rotor side end and a brake side end. A third Bowden cable33is guided from a further brake lever at the handlebar18through the fork steerer12to a front brake at the front wheel10not represented in the drawing. The rotor unit30and further components for bearing or for power transmission, preferably the first Bowden cable31and/or the second Bowden cable32, and the headsets23and25if appropriate, define a rotor system.

The rotor unit30comprises a first transmission element36, which is mounted rotatably and displaceably on the fork steerer12, and a second transmission element37. The first transmission element36comprises for its mounting on the fork steerer12an—at least approximately—ring-shaped area. Preferably, both transmission elements36and37are manufactured as injection molded parts in a resilient plastic material, in metal or in an appropriate compound material. The two transmission elements36and37are mounted rotatably relative to one another and arranged concentrically with the fork steerer12. With respect to a movement along the fork steerer12, the two transmission elements36,37are coupled for entrainment: when the first transmission element36moves upwards along the fork steerer12, it entrains the second transmission element37, and when the second transmission element37moves upwards along the fork steerer12, it entrains the first transmission element36.

The core31aof the first Bowden cable31is at the rotor side in operative connection with the first transmission element36, whereas the core32aof the second Bowden cable32is at the rotor side in operative connection with the second transmission element37. The sleeve of the second Bowden cable32is supported—at least indirectly—by the head tube21, whereas the core32aof the second Bowden cable32with its rotor side end is directly connected to a connecting element32b.

In the present case, the connecting element32bis an injection molded part of metal, however also an appropriately resilient plastic material or another compound material can be used. Moreover, the connecting element32bcan also be produced in another way, for example milled from a metal or forged. Preferably, the connecting element32bis directly firmly connected to the core32aof the second Bowden cable32, in particular pressed with the rotor side end of the core32a, or molded to it or cast or connected in one piece in another way. Alternatively, the connecting element32bis a separate component (I. e. not one-piece with the core32a), in which the core32afor example is clipped, suspended or otherwise form-fittingly introduced or with which the core32ainteracts detachably in another way. For example, a barrel-formed, ball-formed or conical thickened nipple, provided at the rotor side end of the core32a, can be suspended in the alternative connecting element32b, the connecting element32bincorporating it for example with a (upwards open) funnel that preferably is laterally slotted.

The connecting element32bis (in all embodiments) directly form-fittingly attachable at a connection area37bof the second transmission element37, in an aid-free way. For this purpose, the connecting element32bis preferably hook-like and comprises a jut32c, with which the connecting element32bengages from above into an axial guide groove (or another undercut partition) of the connection area37b. As shown in the drawing, the jut32ccan be cuboid or alternatively dovetailed and is introduced into an appropriately formed seat of the connection area37b. By appropriate choice of the fit, the jut32ccan be kept purely form-fittingly, where applicable by appropriate excess also additionally in a force-locking manner. The connection area37bpreferably protrudes radially outwards, in the fashion of an oriel, so that the hook-shaped connecting element32bcan be suspended without needing installation space radially inside the second transmission element37. The connection area37bcan be formed alternatively as a simple groove (without oriel). In both cases, however, the connection area37bis still arranged (completely) inside the head tube21. Due to the stable tension load of the core32a, which is given by a not represented spring of the rear wheel brake, a detachment of the connection during operation can be safely prevented. In case of a repair, however, a very simple, tool-free detachment of the connection is possible.

The connecting element32bcan be formed in various variants. For example, the suspension at the connection area37bcan be developed into a clipping, by providing apart from the jut32ca further jut32d, which is formed nub-like at the lower end of the connecting element32band protrudes radially inwards. This further jut32dpenetrates in an appropriate deepening in the connection area37b, i.e. after an elastic deformation of the connecting element32bthe latter grasps the connection area37b(at least partially form-fittingly), i.e. the connecting element32bis secured like a clip on the second transmission element37. In the drawing, both juts32cand32dof the connecting element32bworking as clip are formed nub-like, they can however have any type of suitable form which allows a safe engagement and hold in case of a tensile load of the core32a.

By means of the rotor system, a brake actuation (I. e. an actuation of the brake lever for the rear wheel brake) is transmitted from the handlebar18to the rear wheel5. The rotor unit30(with its both transmission elements36and37rotatable relative to one another) serves for power transmission from the first Bowden cable31to the second Bowden cable32.

If the user of the bicycle1wants to perform a steering movement, he turns the fork8by means of the handlebar18and thus the front wheel10. In this turning movement the fork steerer12and the first transmission element36are entrained. The second transmission element37remains together with the second Bowden cable32in the position that it has occupied relatively to the head tube21attached to the frame. A shift of the rotor unit41along the fork steerer12does not occur or only imperceptibly.

If the user of the bicycle1wants to brake with the rear wheel brake, he pulls, by means of the brake lever, the core31aof the first Bowden cable31and with it the first transmission element36. Thus the rotor unit41is moved upwards along the fork steerer12so that also the second transmission element37is pulled upwards. The second transmission element37pulls the core32aof the second Bowden cable32, by which the rear wheel brake is actuated. A braking with the front brake is done directly by means of the third Bowden cable33.

Insofar, the embodiments are similar. There are differences in the mounting of the transmission elements36and37and the supply of the Bowden cables31and32. Equal components and components with the same effect have the same reference signs.

In the first embodiment, the basic form of both transmission elements36and37is a cylinder ring (sleeve). The first transmission element36is mounted directly on the fork steerer12in a sliding way, preferably with small backlash. Due to the preferred formation in plastic material, a slidable coating can be dispensed with. The second transmission element37is mounted on the first transmission element36. For this purpose, the first transmission element36has a radial first step protruding inwards36a, on which the second transmission element37is placed by means of a suitable second step37a. The two transmission elements36,37thus are arranged, on the one hand, in axial alignment with each other (due to the areas of the steps extending radially) and at the same time, on the other hand, radially one inside another, i.e. concentrically with each other (due to the axially extending areas of the steps). From the fork steerer12, the second transmission element37is radially distanced, i.e. the internal diameter of the second transmission element37is greater than the internal diameter of the first transmission element36. In axial direction, the two transmission elements36and37are held together by the prestressing in the Bowden cables, in particular of the rear wheel brake.

The dimensions of the rotor unit30are selected in such a way that its axial length is greater than its diameter. The two headsets23and25each have a bearing cup41as the part (of normally three parts) that is to be connected to the head tube21. The funnel-shaped bearing cup41takes up a ball bearing with a large end, whereas with the other tapered end is pressed into the head tube21(or otherwise firmly attached to it). The internal diameter L41of the tapered end of the bearing cup41, thus the internal diameter at the narrowest point of the bearing cup41, amounts to L41=36.0 ±0.2 mm, which is slightly larger than in known bearing cups. In this way, the rotor unit30can be introduced into the head tube21(or if necessary removed from it), even if the bearing cups41of the headsets23and25are already in the head tube21. The external diameter of the large end of the bearing cup41, thus the external diameter at the largest point, amounts to 45.0 mm, which corresponds to that of known bearing cups. The wall thickness of the bearing cup41is generally 1.5 mm. Head tube21with integrated bearing cups41can also be used. The inner diameter of such a head tube21is preferably 36.5±0.2 mm.

For the connection of the first transmission element36with the first Bowden cable31, a bar42is provided having an oblong form similar to a bolt and a cross-section that is definite as possible (i.e. not circular). In the present case, the cross-section corresponds to a rectangle with strongly rounded corners. On the first transmission element36on the radially inwardly facing side, two grooves are formed36b, which face each other radially, extend over a part of the axial length of the second transmission element36, and are accessible from the bottom. By means of these grooves36b, the second transmission element36can receive the bar42, which then extends in radial direction. Instead of the grooves36b, other openings/seats may be provided, for example holes. Preferably, the bar42at each of its ends comprises a catch42a, which, when introducing the bar42into the first transmission element36, dig (engage) into the ground of the grooves36b, so that the first transmission element36and the engaged bar42are connected to each other. Preferably, each groove36bcomprises a small cavity, which receives the assigned catch42afor improving the engaging. On its upper side at both ends, the bar42can have a step so that it abuts at the end of the grooves36band slightly protrudes into the groove-free area of the first transmission element31.

The bar42penetrates the fork steerer12at two fork steerer openings12aradially opposite to each other, i.e. its length is greater than the external diameter of the fork steerer12, and it protrudes in radial direction beyond the outer circumference of the fork steerer12. The fork steerer openings12aare designed as oblong holes, so that the bar42with the first transmission element36, on the one hand, occupies a defined position in circumferential direction and follows a steering movement of the fork8, and, on the other hand, does not obstruct a movement of the rotor unit30along the fork steerer12during a braking.

The bar42is mounted on the core31aof the first Bowden cable31between the end of the core and the sleeve of the first Bowden cable31. For this purpose, the bar42centrally has a channel for the passage of the core31aof the first Bowden cable31and on the bottom a deepening for—preferably form-fitting—insertion of a nipple31bat the end of the core31a(or of an otherwise thickened end of the core31a) of the first Bowden cable31. On this nipple31bthe bar42is seated in the mounted state. Although the bar42and the core31aof the first Bowden cable31are oriented orthogonally towards each other in the mounted state, the bar42is preferably tiltable relatively to the core31a—for facilitating the assembly. For this purpose, the bar42comprises tilts that are oriented towards the channel, and during installation allow a tilting of the bar42relatively to the core31aof the first Bowden cable31. These tilts can be formed symmetric or unilateral and on the upper side and/or on the bottom of the bar42. The drawing shows such alternatives.

The internal diameter of the head tube21is slightly greater than the external diameter of the transmission elements36and37, so that in the head tube21, a head tube opening21ais provided, through which the connecting element32bprotrudes. More precisely, the second Bowden cable32is guided on the outer side of the head tube21up to the head tube opening21a, through which the connecting element32bprotrudes and is connected with the second transmission element37inside the head tube21.

The head tube opening21ais designed as an oblong hole, so that the connecting element32bwith the second transmission element37, on the one hand, occupies a defined position in circumferential direction and remains fixed during a steering movement of the fork8, and, on the other hand, does not obstruct a movement of the rotor unit30along of the fork steerer12during a braking.

The sleeve of the second Bowden cable32is supported on the head tube21preferably in the area of the head tube opening21a. For the support at the outside of the head tube21an appropriate stopper21ccan be applied, for example by means of screwing, as for example disclosed inFIG. 4Athe WO 2012/005610 A2, or by welding. This stopper21ccan be positioned in such a way that, at the same time, it also forms a stopper for the connecting element32bin the lowest position of the connecting element32b. Alternatively, the core32aof the second Bowden cable32can also be deflected, so that the stopper for example may also be provided inside a tube (of the frame3), within which the second Bowden cable32runs. If appropriate, the tube inlet, through which the core32ais introduced into the tube guiding to the rotor unit30, can form the stopper itself, i.e. the core32aruns over a long distance freely inside the corresponding (frame) tube. With an appropriate prestressing in all working conditions, the stopper can also be mounted at the housing like the connecting element, e. g. at the head tube21, or frame3of the bicycle1, i.e. in particular applied form-fittingly on it rather than screwed.

For fastening the stem14at the fork steerer12, a fixing device50is provided. The stem14is pushed on the fork steerer12until it—if necessary interposing a ring—is seated on the upper headset23. The multi-component fixing device50comprises, as a part, a star grip nut52, which is arranged at the upper end of the fork steerer12inside it. The star grip nut52comprises a hollow-cylindrical base body with an internal thread52aand (in the present case each time six) radially distanced star grip nut arms52bat both ends (on top and at the bottom). he star grip nut52is hammered into the fork steerer12so that it is firmly connected to it. The star grip nut internal thread52a, being concentric with the fork steerer12, defines a central star grip nut passage52c. Unlike known star grip nuts, the present star grip nut52comprises an eccentric star grip nut passage52don top and at the bottom between two adjacent arms52.

As further part of the fixing device50, a cap54is provided, which has the form of a plate and is put at the top of the stem14. A centrally arranged centric cap opening54cof the cap54aligns with the central star grip nut passage52c, whereas an eccentric cap opening52daligns with the eccentric star grip nut passage52d.

A fixing screw56as third part of the fixing device50has a fixing screw external thread56a, a fixing screw internal thread56b, a fixing screw longitudinal groove56cand, at the upper end, a fixing screw head56d, in the present case designed as a polygon. The hollow fixing screw56is screwed through the cap54at the cap opening54cinto the star grip nut52, i.e. with the fixing screws external thread56ainto the star grip nut internal thread52a. In this way the fixing screw56tenses the stem14against the upper headset23.

As fourth part of the fixing device50an adjustment screw58is provided. The hollow adjustment screw58has an adjustment screw external thread58b, an adjustment screw longitudinal groove58c, and an—in the present case corrugated—adjustment screw head58d. The adjustment screw58is screwed into the fixing screw56, i.e. with the adjustment screw external thread58binto the fixing screw internal thread56b. Adjustment screw58, fixing screw56and star grip nut52are thus concentric with each other and arranged towards the fork steerer12.

The first Bowden cable31is guided from the handlebar18to the fixing device50, where its sleeve is supported by the adjustment screw58, whereas its core31is guided through the hollow adjustment screw58—and thus also through the hollow fixing screw56, the centric cap opening54cand the central star grip nut passage52c-into the fork steerer12up to the bar42. The relative position of adjustment screw58and fixing screw56generates a tension in the first Bowden cable31. In order to introduce the core31aalso with nipples at both ends into the hollow screws56and58, the adjustment screw longitudinal slot58cand the fixing screw slot56care provided, through which the core31aof the first Bowden cable31can be introduced laterally into the screws58and56. Useful care is taken to ensure that, in case of mounted fixing device50, the longitudinal slots56cand58care not congruent, in order to prevent an excessive lateral buckling of the core31a.

The third Bowden cable33, which is centrally guided instead of the first Bowden cable31in known fixing devices, is eccentrically guided in the present fixing device. I.e., the third Bowden cable33is guided through the eccentric cap opening54dand the eccentric star grip nut passage52dinto the fork steerer12up to the front brake.

A modified fixing device50consists of the adjustment screw58and of a modified fixing screw56′. The modified fixing screw56′ comprises a larger diameter and is screwed by means of its external thread directly into the fork steerer, in which for this purpose an internal thread was cut. The modified fixing screw56′ comprises a fixing screw internal thread56b, in which the hollow adjustment screw58is screwed. The guiding of the core31aof the first Bowden cable31is done as described before. The third Bowden cable33is guided through an eccentric passage (in the present case with a kidney-shaped cross-section) into the fork steerer12.

For the assembly of the fork8, in a first step, the star grip nut52is hammered into the fork steerer12. In a second step, the first Bowden cable31(with bar42) is pushed upwards from the bottom through the fork steerer12and through the star grip nut42, while the bar42is tilted relatively to the core31aof the first Bowden cable31when it arrives in the fork steerer12. In a third step, the bar42(simultaneously tilting back relatively to the core31a) is put with its ends through the fork steerer openings12aso that the bar42is in the correct position. In a fourth step, the rotor unit30is pushed from above onto the fork steerer12, until the bar42is engaged in the first transmission element36. The preassembled unit obtained in this way is then, during installation of the whole bicycle1, in a fifth step, pushed into the head tube21. In a sixth step, the stem14is set up and the fixing device50completed, i.e. by tightening the fixing screw56, the fork8is fixed (clamped). In a seventh step, the second Bowden cable32with the connecting element32bis fixed at the connection area of the second transmission element37, for which purpose the connecting element32bis introduced through the head tube opening21, and suspended (and/or clipped) in the way described above.

The fixing device50according to the invention is particularly conceived for forks8whose fork steerer12finishes with a diameter of 1⅛″ (28.6 mm). However, forks are also known whose fork steerer finishes with a diameter of 1″ (25.4 mm) and can have a thread outside. The fixing device known for this purpose, which also could be used in the present case alternatively to the fixing device50, consists of a steerer stem which is thickened at its upper end so that the stem14can be pressed or clamped onto the steerer stem (I. e. on its top). At its lower end, the steerer stem is slanted (as a cylinder cut). The steerer stem is penetrated along its length by an adjustment screw, which extends centrally in axial direction and is accessible from the top. By means of this adjustment screw, the two sections of the steerer stem are displaceable in relation to each other, i.e. along the tilted cut surface. Introduced into the fork steerer12, the two sections of the steerer stem can be supported by the inner wall of the fork steerer12and be clamped mutually. In this way, the stem14is fixed at the fork steerer12. The optionally present thread outside on the fork steerer12serves to bias, by means of a union nut, the upper headset25in axial direction and to keep together its components. In order to be able to introduce also the third Bowden cable33into the fork steerer12, the steerer stem preferably comprises an additional opening, for example besides the head of the adjustment screw.

The second embodiment (FIG. 7C) coincides with the first embodiment, unless otherwise described in the following. Here too, the core31aof the first Bowden cable31extends inside the fork steerer12; the introduction into the fork steerer12can occur at any location, in principle, for example through the stem or directly from the brake levers at the handlebar, preferably with the above described fixing device50(or the alternative, known fixing device). At the end of the core31a, in the present case, a bar42in plastic material is molded in one piece. In the present case, the production of the corresponding Bowden cable is done by introducing the core into the sleeve, afterwards at one end the bar42and at the other end (not shown) a nipple are molded for the brake lever, so that the core31acan no longer be removed from the sleeve without destruction of the bar42or of the nipple, which has great advantages with regard to production. However, bar42and core31acan also be separately formed—as in the first embodiment —, i.e. the core31acan be introduced, for example, into an opening provided in the bar42and be clamped with it.

The sleeve-shaped first transmission element36is displaceable in axial direction on the fork steerer12. The ends of the bar42protrude through oblong-hole-shaped fork steerer openings12ain radial direction something beyond the outer circumference of the fork steerer12and are incorporated in downwards open slots of the first transmission element36. Two downwards open slots facilitate the assembly. In principle, however, a slot or oblong hole is also possible in connection with an opening adapted to the form of the bar42on the opposite side or two openings adapted to the form of the bar42. When the bar42is at the lower end of the fork steerer opening12a, the free area above the upper side of the bar42and the upper end of the fork steerer opening12ahas a length L36.

With the first transmission element36, the second transmission element37cooperates, which in the present case is formed by a displaceable ring placed directly on the fork steerer12above the first transmission element36with the connection area37b. The connection area37band the connecting element32bare formed as described above.

In the present case, the connecting element32bprotrudes through a head tube opening21atowards outside the head tube21, i.e. the core32aof the second Bowden cable32ain the present case also extends outside the head tube21. The head tube opening21ais, in the present case, oblong-hole-shaped, and in the non-operated state of the Bowden cables31,32the distance between the upper side of the connecting element32binside the head tube opening21aand the upper end of the head tube opening21a, thus the free area in the head tube opening21a, is designated with L37. As to the aforementioned length L36, in the present case L37is maximally equal ample (preferably slightly greater than L36), i.e. the fork steerer opening12aserves as safety limit for the maximum shift of the transmission elements36,37, so that the connecting element32ais not damaged by forces from the top. On the other hand, in case of a definition of L44equal L55, it can be ensured additionally that in the case of a design of the connecting element32bwith a jut32cto be introduced into a seat of the connection area37b, the connecting element32bis completely introduced. The different or same lengths L44and L55can be realized also in the first embodiment similarly and with equal function. The support of the sleeve of the second Bowden cable32is done as in the first embodiment.

In the third embodiment (FIG. 8) the rotor unit30and the first Bowden cable31are arranged completely outside of the fork steerer12, in a similar manner to how it is already disclosed in DE 199 29 093 C2.

The first transmission element36generally consists of a sleeve that, with small backlash, embeds the fork steerer12, and whose top is one-piece with a ring-shaped flange extending outwards. By means of a sliding bearing, the first transmission element36embedding the fork steerer12is mounted smoothly on the fork steerer12which, in the present case, consists of polished steel. The first transmission element36is, in the present case, injection molded in plastic material. At the lower end of the sleeve, a groove is formed, in which a holding element84is incorporated in the form of an elastic ring. Above the holding element84, a washer86is placed.

Between the flange of the first transmission element36and the washer86, the second transmission element37is arranged on the sleeve. The second transmission element37generally consists of a ring, which also is injection molded in plastic material. The sleeve in this area has a continuous cylinder-shaped smooth outside so that the ring is easily rotatable relatively to the sleeve. The second transmission element37at its upper edge in the present case on one side comprises the connection area37b. In axial direction, the second transmission element55together with the other parts of the rotor unit30is arranged in a displaceable way on the fork steerer12, however immovably as to the first transmission element36due to prestressing of the Bowden cables31,32. For the two transmission elements36,37, the head tube21forms a housing, which offers protection in radial direction (with respect to the turn of the transmission elements36,37). As shown in the drawing, the head tube21forms a part of the frame3.

The sleeve of the first Bowden cable31is fixed by means of a threaded joint at the stem14on its upper side, whereas the core31aof the first Bowden cable31is guided through a vertical hole of the stem14on its bottom. Through an opening in the upper headset25, the core31ais guided into the interior of the head tube21and connected with the flange of the first transmission element36, in the present case directly suspended in a slot in the flange. The flange corresponds in its transfer function to the above described bar42. The connecting area is accessible from the outside preferably through a, for example, oval head tube opening21ain the head tube21. The head tube opening21ais covered preferably by a (not represented) cap. The head tube opening21aalso can be formed differently, moreover it does not have to be arranged necessarily in the front, at the control ear21, but for example also laterally.

The second Bowden cable32is supported with its sleeve by the head tube21or in the present case by an adapter piece between lower headset23and head tube21, whereas the core32aof the second Bowden cable32is guided through an opening in the lower headset23or in said adapter piece into the interior of the head tube21. As described above, the core32aof the second Bowden cable is connected by means of a connecting element32bwith a connection area37bof the second transmission element37. For a simple assembly of the connection element32band the core32aof the second Bowden cable32, the head tube opening21acan be far greater and extend on one side laterally over the head tube21. However also a second opening at a suitable location can be provided.

The third Bowden cable33for the front brake is pulled through a channel not represented in the drawing in the hollow fork steerer12. If with only one brake lever the rear wheel brake and the front brake are to be actuated at the same time, at the rotor unit30in an appropriate way (i. e. by means of a further connecting element and of a connection area) the core of the third Bowden cable33can be fixed, which can be guided through the lower headset23to the front brake. The fastenings of the two second cores take place in the present case preferably displaced by 180° to each other. Obviously it is also possible to provide brake levers on either side of the handlebar, the function of the brakes being identical. In the present case, two cores are applied at the flange of the first transmission element36.

According to a modification (FIG. 9) of the third embodiment, the core31aof the first Bowden cable31is also connected with the first transmission element36by means of a connecting element, which is formed for example like the connecting element32bor its variants, and a connection area, which is suitably formed and with which the connecting element is connected. The first transmission element36comprises said connection area at its upper edge. Due to the prestressing of the core31aof the first Bowden cable31, both the core end in the connecting element (in case of a separate formation) and the connecting element in the connection area are engaged against gravity.

For reasons of precaution, it is pointed out that—for example when using two different Bowden cables for rear wheel brake and gear change—also a combination of two of the abovementioned rotor units (or a combination with a rotor unit arranged outside of the head tube21) is possible, which are arranged axially one upon another. The combination of the rotor unit30of the third embodiment or its modification, which is arranged in the head tube21on top, with a rotor unit30of the first or second embodiment, which is arranged in the head tube21at the bottom, is preferred. Since the first Bowden cable31is guided to the lower rotor unit30inside the fork steerer12and that to the upper rotor unit30outside of the fork steerer12, and since the two second Bowden cables32can be arranged at different places of the head tube21, the two rotor units30do not obstruct each other in case of a rotation movement of the fork8.