DE102016004400A1 - Forged handlebar stem for bicycles and the like - Google Patents

Abstract

Forged handlebar stem (1) for bicycles and the like, which is clamped on the steerer tube of the fork of a bicycle and consists essentially of a handlebar clamping head (3), which is connected with its inner part with a longitudinally extending connecting tube (2) , wherein at the opposite end of the connecting tube (2) a steerer tube clamping head (20) is integrally formed, wherein the handlebar stem (1) is formed as a continuous material einstückiges part, saving material-separated clamping shells.

Description

The invention relates to a forged, particularly lightweight handlebar stem for bicycles and the like, which is clamped on the steerer tube of the fork of a bicycle and consists essentially of a handlebar clamping head, which is connected with its inner part with a extending in the longitudinal direction of the bicycle connecting tube, wherein at the opposite end of the connecting tube, a fork stem clamp head is formed.

Such a stem is, for example, with the subject of DE 10 2012 016 907 A1 known. Disadvantage of the known handlebar stem is that the handlebar clamping head is formed two or more parts and consists of an approximately half-shell-shaped element which is integrally formed on the connecting tube and which thereby forms the handlebar clamping opening by another shell-shaped, separate part by means of a screw connection to the half-shell can be screwed on the connecting pipe.

The separate, half-shell-shaped, screw-on part is also referred to as a clamp, which may be formed in one or more parts.

The handlebar stem shown there is a forged part, and the reason for the formation of the handlebar clamping head of two separable parts is the relatively difficult forging of the handlebar stem.

By the term forging, the invention means a sudden chipless pressure forming of metals by pressing between two tools with local change of the cross-sectional shape. Advantages are less material loss in contrast to the machining and the targeted change of Feiningefüges, so the crystal structure. A disadvantage is the lower accuracy compared to cutting methods.

Forging is, with a few exceptions, all metals and metal alloys. The forming takes place during forging usually at higher temperatures than at the service temperature with a change in the metal structure or high pressure even at normal temperature. The processing temperature is either above the recrystallization temperature (hot working) or below the recrystallization temperature (cold forming).

The forging process also includes casting or rolling the blank, hardening and tempering, and grinding. Compared to casting, the material remains in the solid state and is machined with a hammer and anvil or with machines such as air hammers and presses.

The object of DE 10 2012 016 907 A1 Helps with the problem of poor accessibility of the interior of the workpiece to be reshaped (handlebar stem) in that the front clamping cover of the handlebar clamping head is removable, so as to make the inner diameter of the forged connecting tube of the handlebar stem for a forging and machining accessible.

Disadvantage, however, is the need to use the half-shell-shaped, end-side clamping bracket, which requires a total of at least two clamping or clamping screws, but usually four clamping screws are required, as shown in the DE 10 2012 016 907 A1 in the local 1c is shown.

The 4c shows the separate and aufzuschraubenden clamps, which is associated with serious disadvantages in terms of a desired weight saving.

Per saved clamping screw a weight of about 5% of the total weight of the handlebar stem is saved, and this results in the disadvantage of said handlebar stem, because due to two clamps used and a total of four clamping screws the handlebar stem an undesirably high weight.

The manufacturing costs and the storage costs are higher, because separate parts must be stored and manufactured.

The processing is more difficult, because due to existing processing tolerances, the separate clamping bracket must be adapted exactly to the half-shell-shaped handlebar clamping head to create a total of a consistently over the entire circumference exciting clamping opening.

By the use of half-shell clamps, which are each secured with two associated upper and lower clamping screws on the handlebar clamping head, an unfavorable power transmission of a there clamped handlebar is given to the handlebar stem incidentally.

With the subject of EP 2 305 550 A1 is also shown a forged handlebar stem, in which instead of the four clamping screws now used only two clamping screws are used, but also a separate Clamp is necessary. Again, there are the same disadvantages as stated above, namely an unfavorable power transmission of bending moments of the handlebar on the handlebar stem due to the separate clamping connection and incidentally an unfavorably high weight.

With the subject of EP 2 318 149 A1 is shown consisting of a plurality of shell-shaped clamping straps clamping connection for the handlebar clamping head, which is associated with the same disadvantages.

The invention is therefore based on the object, starting from the DE 10 2012 016 907 A1 to develop a forged handlebar stem so that a significantly reduced weight is ensured with much better transmission of bending moments from the handlebar to the handlebar clamping head.

To solve the problem, the invention is characterized by the technical teaching of claim 1.

An essential feature of the invention is that now the handlebar stem according to the invention is designed as a continuous material einstückiges part.

With the given technical teaching, there is the advantage that now no detachable parts are arranged on the handlebar stem, in particular no clamps that need to be fixed with separate clamping or clamping screws, but there are a total of coherent material integral with each other (material connected) parts available in that the handlebar stem consists of a connecting tube on which the handlebar clamping head is integrally formed, in that the fork stem clamp head is also formed on the opposite end of the connecting tube and all parts are designed as tension connections for the steerer tube or for the handlebar tube, without being materially separated, There are separate clamping brackets, which can be screwed on with separate clamping screws.

This results in the advantage of a significant weight saving, because it will avoid the considered as increasing the weight clamping screws and the total number of clamping screws is reduced.

The invention therefore provides, in a preferred embodiment, that the handlebar clamping head side clamping connection consists of two mutually parallel clamping screws.

In another embodiment can be provided that only a single handlebar clamping head side clamping screw is used.

On the opposite side, namely on the side of the fork stem clamp head, two clamping screws or even a single clamping screw are also used.

It is therefore crucial in the invention that in particular the handlebar clamping head is designed as a material integral part, d. H. there are not mutually complementary shells present, which are screwed together only during assembly. Rather, the handlebar clamping head forms a continuous self-contained part, which is divided only by a transverse clamping slot.

Instead of a half-shell according to the invention a solid shell for the handlebar clamping head is used, which can be closed exciting only in the region of a clamping slot via associated clamping screws (one or two clamping screws), so as to form a high-load-transmitting clamping opening for the introduced there in the terminal opening handlebars.

Thus, much higher bending moments can be transmitted from the handlebar to the handlebar clamping head, because only one - preferably lower - clamping slot is present, which is closed by the one or two clamping screws or open, so that the upper horizontal region of the handlebar clamp head closed is, therefore, material is continuously formed, and so a half-shell-shaped, removable, strinseitiger clamp with poor load transfer is avoided.

According to the invention thus the handlebar clamping head is closed at its front side in itself and has just there not a half-shell-shaped clamping bracket, as it said DE 10 2012 016 907 A1 disclosed.

The material integral design of the handlebar clamp head and the rest of the training of the other parts of the stem are purchased at a forging according to the invention with certain problems, which are solved according to the invention, however, in a special way.

In the case of a forged handlebar stem, it is important that the entire handlebar stem is forged using a forging tool and, in particular, that the interior of the connecting tube be forged.

For the reason mentioned, because in the interior of the connecting pipe with a want to get suitable forging tool, the front side of the handlebar clamping head is open in each case in the prior art and can therefore be closed later, after the forge machining, by a separate there to be attached clamp. The associated disadvantages have been described above.

Thus, in the present invention, a lightweight, forged handlebar stem is possible, in the connecting pipe frontally a forging tool can retract, the invention provides that on the front side of the handlebar clamp head a suitable front side opening is provided which leads approximately in alignment with the interior of the connecting tube.

The invention therefore consists in driving through the end-side handlebar clamping head opening (which is arranged on the front side of the handlebar clamping head) with a suitable forging tool so as to reach the interior of the connecting pipe in order to forge out this connecting pipe.

The attachment of an end of the invention Lenkerklemmkopföffnung also has the further advantage that a clamping tool, such as. As a cutter, a broaching tool, a honing tool, an eroding tool or other suitable cutting tool can be introduced so as to edit the interior of the connecting pipe by machining.

Important in the invention is therefore that an end-side handlebar clamping head opening is provided in the handlebar clamping head, which is adapted to be penetrated by a suitable forging tool and / or to be penetrated by a suitable cutting tool, which is able to the interior of the connecting pipe to to edit.

The dimensioning of this front opening has certain features, all of which are claimed as essential to the invention in the present invention.

In a first embodiment, it is provided that the front side of the end opening is profiled round, but is smaller in diameter than the inner diameter of the connecting pipe.

Thus, a machining of the inner tube of the connecting tube is achieved so to speak in a keyhole operation, because with a suitable cutting tool through the relatively small sized end-side handlebar clamp opening can be driven through so as to edit the inner wall of the connecting tube in the direction perpendicular to the longitudinal axis of the connecting tube.

Advantage of attaching a relatively small handlebar clamp opening is that much material can stop on the handlebar clamp head and therefore a high load transmitting exciting connection for attachment of the handlebar is possible.

Thus, such a handlebar stem high bending moments of the handlebar record, because a considerable material structure in the surrounding area of the handlebar clamp opening at the front of the handlebar clamp head stops.

Impermissible bending, flaking of the clamp, an inadmissible shearing of the clamping screws and the like, as is known from the prior art, are avoided in the invention.

This material is also saved at the same time, because it accounts according to the invention over the prior art, at least two clamping screws and the associated terminal connections.

In the world of high performance bicycles, weight savings of 10 grams mean worlds, and thus the handlebar stem according to the invention is far superior to known stem formers in terms of weight saving and bending load transfer.

However, the invention is not limited to round, relatively small sized end-side handlebar clamp head openings, but instead of a round small dimensioned handlebar clamp opening and square or polygonal or non-round handlebar clamp head openings can be used.

In the following embodiments, in addition to a round, front-side handlebar clamping head opening and a square handlebar clamping head opening is described. However, the invention is not limited thereto. Instead of a square opening also any other profiled end side openings (handlebar clamp openings) can be used.

It is in the above description for the time being only to the front side of the handlebar clamp opening, because this continues in the region of a line of flight, which coincides with the center longitudinal line of the connecting tube, in a rear side opening, which connects directly to the outer contour of the connecting tube and there the transition creates the connection pipe.

Thus, in the region of the handlebar clamping head opening there are a total of two mutually aligned end-side openings, namely the front end-side opening, which is visible from the front side and the front-side opening located in the direction of escape, which adjoins the circumference of the connecting tube.

It is not necessary for the solution, that the front, frontal and visible front side opening is equally profiled and has the same contour as the behind in alignment lines subsequent, further front side opening, which adjoins the connecting pipe.

The front, visible side arranged front side opening may be formed small in diameter and be profiled in any way, while in the direction of escape behind it subsequent and creating the transition to the connecting pipe end face opening may be profiled differently and may also have a different dimension.

It is preferred if the diameter or the clear width of the front end side opening is smaller than the inside width of the front side opening adjoining in the direction of escape.

In another embodiment of the present invention, it can be provided that the inside width of the front end opening is the same size as the inside width of the rear end opening.

And in a third embodiment, it may be provided that the front end side opening, which adjoins the connecting pipe, is larger than the rear, arranged on the visible side end opening in the handlebar clamping head opening.

The invention therefore consists in that a handlebar clamping head is integrally formed on one side of a connecting tube, which consists of a forged metal material, and on the opposite side a fork stem clamping head, wherein the two mentioned clamping head parts pass over transitional areas into the connecting tube of smaller diameter ,

Thus, the contours of the handlebar clamping head and the fork stem clamping head exceed the outer contour of the connecting tube and the two mentioned head portions are material integrally formed on wall-side transition regions to the smaller diameter outer connecting tube.

The invention is not limited to the formation of a round contour for the connecting pipe. In preferred embodiments, the connecting tube has a rectangular or square profiling.

The connecting tube can thus assume any desired profile shape, in particular also a polygonal profile shape, which, preferably symmetrically, consists of several polygons.

In one embodiment of the invention, it may also be provided that the front side opening at the handlebar clamp opening is omitted altogether.

Again, the same description of features apply to the same parts, which is characteristic in this embodiment that the handlebar clamping head is closed in itself and a handlebar clamping head is eliminated altogether.

A forging of such a handlebar stem then takes place in that the handlebar clamping head is formed in itself as a bendable part and consists of two material integral with each other half shells which are connected to each other via a metallic bending edge.

That is, the handlebar clamping head is a material integral part as a whole, but a half-shell is wegbiegbar of the other half-shell of the handlebar clamping head, so as to open an end opening of the connecting pipe and machined in this open state, the interior of the connecting pipe machined or forging.

After the machining or forging machining of the connecting tube, the handlebar clamping head (the half shell) opened over the bending edge is then bent down again and thus forms a self-tapping, self-contained handlebar clamping head, without the need for a front-end handlebar clamping head opening.

In another embodiment, it may be provided that the raw material of the handlebar stem is already machined in the unfolded position of a half-shell and forging, and then the originally folded-up shell half is folded down and then a self-contained handlebar clamping head after machining and forging machining forms with the missing frontal opening.

When the term "upper" and "lower" parts are used in the above description, this only means referring to the drawings. Of course, the handlebar stem according to the accompanying drawings also rotated by 180 °, so that then the names above and below are reversed mutatis mutandis.

It has been found in the forging with the use of a one-piece handlebar clamp head and, of course, a one-piece steerer clamp that a total of 10% of the weight can be saved over known Lenkervorbauten.

As a preferred material for the handlebar stem, a light metal alloy is used, but other metal alloys come into question, such as. For example, titanium alloys, steel alloys and the like.

Such a stem can also be produced by die-cast aluminum, which gives the same advantages.

The subject of the present invention results not only from the subject matter of the individual claims, but also from the combination of the individual claims with each other.

All information and features disclosed in the documents, including the abstract, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are novel individually or in combination with respect to the prior art.

As far as individual items are referred to as "essential to the invention" or "important", this does not mean that these items necessarily have to form the subject of an independent claim. This is determined solely by the current version of the independent claim.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

Show it:

1 : Perspective view of a handlebar stem according to all embodiments

2 : Perspective view of a handlebar stem in a first embodiment

3 : Cut in a middle longitudinal line by the representation after 2

4 : the first embodiment according to 2 and 3 with a section along the line IV-IV in 3

5 : A perspective view of a second embodiment of a handlebar stem

6 : Cut through the handlebar stem after 5

7 : a middle longitudinal section through the representation after 5

8th : also a middle longitudinal section through the representation after 5 in perspective view

9 : A perspective view of a third embodiment of a handlebar stem

10 : A perspective longitudinal section through the representation after 9

11 : A perspective view of a fourth embodiment of a handlebar stem

12 : Center longitudinal section through the execution after 11

A handlebar stem, as it corresponds to all embodiments in its construction, is with the handlebar stem 1 in 1 shown. It consists essentially of an approximately central connecting tube 2 , at the two ends of each of the clamping heads are formed. On the right in 1 is the steerer tube clamp 20 on the connecting pipe 2 molded on, while on the left after 1 to the connecting pipe 2 over a transitional area 14 the handlebar clamping head 3 is formed.

The handlebar clamping head 3 forms a clamping opening 4 from, which is penetrated by a handlebar, not shown.

The clamping opening 4 is defined by a width-adjustable clamping slot 5 , which is interrupted by a clamping connection, said clamping connection in the illustrated embodiment of two mutually parallel clamping screws 6 . 7 exists, which are arranged at a mutual distance from each other.

However, the invention also relates to the arrangement of only a single, central clamping connection, the clamping slot 5 then bridged in the middle.

For better clarity because of the fork stem side clamping connection is shown, which consists essentially of two mutually parallel clamp connections 29 exists where each Clamping connection consists of a clamping screw in an associated hole 23 is inserted and with its bolt-side end in an associated threaded hole 30 beyond the clamping slot 22 is screwed.

In this way is also the fork shaft side clamping opening 21 with a clamping slot 22 provided whose clamping width through the said clamp connection 29 is changeable.

In the embodiment shown, it is shown that the threaded holes 30 are arranged for engaging the clamping screws, not shown, each on one side of the fork stem clamp head. It can also be provided that the threaded holes 30 offset from one another, in which case the one threaded hole 30 on the right side and the underlying threaded hole, for example, is arranged on the left side.

In the embodiment of the 2 to 4 a first embodiment is shown, which consists in that on the front side of the handlebar clamp head 3 an inventive handlebar clamp opening 8th is arranged, which consists of two mutually aligned through holes.

The front, visible side end opening is denoted by the reference numeral 8a referred to while in the alignment behind lying end opening with 28a is designated.

The important thing is that the contour 9 the front end opening 8a from the contour 10 the rear face opening 28a may differ. It can be different both the contour and the inside width of the mutually aligned end side openings 8a . 28a ,

In the embodiment shown is still shown that clamping screws 6 . 7 are present, the clamping slot 5 bridge over so the clear width of the terminal opening 4 adjust.

Out 3 and 4 This results in that the clamping connection with the two clamping screws 6 . 7 It consists in that a threaded hole 11 is present, the opposite a through hole 12 assigned. In the through hole 12 is the respective clamping screw 6 . 7 used and engages with its bolt-side end in the threaded hole 11 one.

For the embodiment of the 2 to 4 is characteristic that the handlebar clamp opening 8th is smaller dimensioned than the contour comparatively 10 the interior of the connecting pipe 2 ,

The forging machining or machining therefore carried by the front-side handlebar clamp opening 8th in the direction of the arrow 19 with a suitable tool, which through the frontal opening 8th passes through and it is recognizable that the contour 9 (clear width) of the front side handlebar clamp opening 8a smaller than the connection tube side contour 10 of the connecting pipe 2 ,

It results from the front side opening 8a two parallel alignment lines 15 . 16 in their distance (contour 9 ) are smaller than comparatively the inner contour 10 (clear width) of the connecting pipe 2 ,

If now with a suitable tool through the smaller dimensioned front opening 8a is driven through, then this tool moves along the alignment lines 15 . 16 , and there are opposing interior areas 17 . 18 of material of the connecting pipe 2 left over, which are removed with suitable cutting tools.

Before the removal of the interior areas 17 . 18 however, with suitable machining tools, the entire interior of the connection pipe becomes 2 machined with a suitable forging mandrel, which is therefore aligned in the direction of arrow 19 through the front-side handlebar clamp head opening 8th is driven through and with the outer diameter approximately with the alignment lines 15 . 16 coincides and then as a counter tool a forging of the inner wall of the connecting pipe 2 allows.

After forging, with still standing material areas in the interior areas 17 . 18 These are subsequently applied to the interior areas 17 . 18 in the direction of the arrows 25 . 26 ablated.

Incidentally, it is not necessary for the solution, that the thickness of the inner wall of the connecting pipe 2 is the same thickness as in 3 shown. It can also deviating wall dimensions for the connecting pipe 2 by the said machining in the arrow directions 25 . 26 be made.

Incidentally, the show 2 and 3 that from the handlebar clamping head 3 having a larger outer contour, the diameter reducing transition areas 24 a material integral connection to the circumference of the connecting pipe 2 provide.

In the embodiment according to 2 to 4 By the way, it is shown that the directly to the connecting pipe 2 adjoining rear face opening 28a about the inner diameter of the connecting pipe 2 in finished and forged condition.

The invention is not limited thereto. The front side opening 28a does not have to be the same size and dimensioned with the same width as the front side opening 8a ; However, it can also be larger in size, as in the embodiments according to 2 to 4 is shown.

Likewise, a material processing of the inner wall in the area of the interior areas 17 . 18 of the connecting pipe 2 in the way possible that the connecting tube with conical wall thickness of the handlebar clamping head 3 with a thinner thickness tapered towards the adjoining fork clamp head 20 continues.

In the embodiment according to 4 the same parts are provided with the same reference numerals.

Here it can be seen that the front end opening 8a a contour 9 having a relatively small diameter and which are aligned with the alignment line 13 subsequent end opening 28a a same contour 10 has, as the inner diameter of the connecting pipe 2 ,

The invention is not limited thereto. When the rear end opening 28a has a smaller contour, the z. B. is greater than the contour 9 , results in the transition area 14 a paragraph.

The connecting pipe 2 therefore has a non-circular inner contour 27 when you're in 4 on the bottom-side inner contour 27a looks at while the 3 the view on the side wall of the inner contour 27b represents.

The 5 to 8th show a further embodiment, wherein for all parts the same description according to the first embodiment of the 2 to 4 applies.

In contrast to the embodiment according to 2 and 4 is the front face opening 8a roughly square profiled and forms an approximately square contour 9 in the front area while facing the flight line 13 behind subsequent further front opening 28a another contour 10 has, for example, polygonal, round or otherwise formed polygonal.

So it is not necessary for the solution that the contour 9 the front end opening 8a the contour 10 the rear face opening 28a equivalent.

When arranging a square contour, it is possible to drive with a blacksmith tool adapted to the shape around an approximately also square cross-section of the connecting pipe 2 auszuschmieden.

The 9 and 10 show a third embodiment, in which it is shown that the front-side handlebar clamp opening with the front side opening 8a in alignment with the behind it adjoining front side opening 28a completes and that both end openings 8a . 28a approximately in alignment with each other and with the same contour.

This has the advantage that a particularly simple forging machining is possible and subsequent machining in the interior of the connecting pipe 2 is particularly easy or can be omitted. In this embodiment, then only a forging machining of the connecting pipe 2 occur.

However, the material cross sections in the region of the handlebar head opening due to the relatively large-sized end openings 8a . 28a relatively small, so that a slightly less favorable transfer of bending moments from the terminal opening 4 , which is penetrated by the handlebar, not shown, on the handlebar clamping head 3 given is.

The worse load transfer is, however, compensated by the fact that the clamping connection in the lower area, which the clamping slot 5 bridged, stronger dimensions can be.

The arranged in this region of the clamping connection material cross-sections are then formed larger.

In one development of the invention, it can also be provided that at least one of the clear width of the front side opening 8a approximately centrally bridging web of the material of the handlebar clamping head is present, so that the handlebar clamp opening is not formed circumferentially continuous, but is interrupted by an approximately central web, which is materially connected to the material of the handlebar clamping head.

In this case, a center-split forging mandrel is used, which is pushed over this central web, so as to use a split forging mandrel the interior of the connecting pipe 2 auszuschmieden.

The 11 and 12 show a fourth embodiment of the invention, in which a total of a material einstückiger forged handlebar stem 1 is shown, in which a front-side handlebar clamp opening 8th completely eliminated.

In this case, it is envisaged that the forging of such a handlebar stem takes place by the fact that during roughing the handlebar clamping head 3 with its front shell half 32 is pivoted upward, ie in the opposite direction to the arrow 35 so that it forms an open mouth so to speak, so as to open the front opening of the connecting pipe 2 to clear for internal processing. Accordingly, the shell half 32 from the fixed shell half 33 in the opposite direction to the arrow 35 swung off and becomes a bending edge 31 on the shell half 33 material is integrally formed, in the counterclockwise direction (arrow 34 ) pivots.

After completion of the forging and other workpiece machining of the so highly pivoted or highly curved shell half 32 this will be in the direction of the arrow 35 bent down again, so the self-contained clamping opening 4 to form that of the clamping slot 5 is interspersed.

In this way, all in all on a front end opening 8a be dispensed with, leaving only the rear face opening 28a is available.

For reasons of weight saving, it is also possible in the exemplary embodiment 11 be provided that in the front side of the front shell half 32 a groove 36 is milled. The contour of the groove 36 can be shaped in any way, because it only serves to save weight and is not intended that a material processing of the interior of the connecting pipe 2 through this groove 36 takes place.

LIST OF REFERENCE NUMBERS

1

stem

2

connecting pipe

3

Handlebar clamp head

4

Clamp opening (from 3 )

5

clamping slot

6

clamping screw

7

Handlebar clamp head opening

8a

Front side opening (front)

9

Contour of 8a

10

Contour of 28a

11

threaded hole

12

Through Hole

13

Line of Flight (middle)

14

Transition area

15

alignment

16

alignment

17

interior

18

interior

19

arrow

20

Steerer clamp head

21

Clamp opening (from 20 )

22

clamping slot

23

drilling

24

Transition area

25

arrow

26

arrow

27

Inner contour (from 2 ) a, b

28a

Rear opening at the rear

29

clamp connection

30

threaded hole

31

bending edge

32

Shell half (front)

33

Shell half (rear)

34

arrow

35

arrow

36

groove

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012016907 A1 [0002, 0008, 0009, 0017, 0028]
• EP 2305550 A1 [0015]
• EP 2318149 A1 [0016]

Claims (10)

Forged handlebar stem ( 1 ) for bicycles and the like., Which is clamped on the steerer tube of the fork of a bicycle and essentially from a handlebar clamping head ( 3 ) with its inner part with a longitudinally extending connecting pipe ( 2 ) is connected, wherein at the opposite end of the connecting tube ( 2 ) a steerer tube clamping head ( 20 ) is formed, characterized in that handlebar stem ( 1 ) is formed as a continuous material einstückiges part. Handlebar stem according to claim 1, characterized in that the handlebar stem consists of self-contained parts (material-bonded together) ( 2 . 3 . 20 ) consists. Handlebar stem according to claim 1 or 2, characterized in that the handlebar clamp-side clamping connection ( 3 . 5 ) at least one and preferably two mutually parallel clamping screws ( 6 . 7 ) assigned. Handlebar stem according to one of claims 1 to 3, characterized in that the handlebar clamping head ( 3 ) is a continuous self-contained part, which by a transversely extending clamping slot ( 5 ) is interrupted. Handlebar stem according to one of claims 1 to 4, characterized in that on the front side of the handlebar clamping head ( 3 ) an end opening ( 8a . 28a ) is arranged approximately in alignment with the interior of the connecting tube ( 2 ). Handlebar stem according to claim 5, characterized in that the handlebar head side end side opening of two approximately mutually aligned end face openings ( 8a . 28a ), and that the front end opening ( 8a ) is smaller in diameter than the inner diameter of the connecting tube ( 2 ). Handlebar stem according to one of claims 1 to 6, characterized in that the contour of the front end opening ( 8a ) is different from the contour of the rear end opening ( 28a ). Handlebar stem according to one of claims 1 to 7, characterized in that the diameter or the inside diameter of the front end opening ( 8a ) is smaller or the same size as the inside width of the front side opening adjoining in the direction of escape ( 28a ). Handlebar stem according to one of claims 1 to 8, characterized in that the contours of the handlebar clamping head ( 3 ) and the steerer tube clamping head ( 20 ) the outer contour of the connecting tube ( 2 ) and the two head parts ( 3 . 20 ) via wall-side transition regions to the outer diameter smaller connecting tube ( 2 ) are material integrally formed. Handlebar stem according to one of claims 1 to 9, characterized in that at least the handlebar clamping head ( 3 ) of two along a bending edge ( 31 ) mutually bendable and one-sided material-connected half-shells ( 32 . 33 ) consists.

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