Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDECARS, FORECARS, OR THE LIKE
  • B62K21/00—Steering devices
  • B62K21/18—Connections between forks and handlebars or handlebar stems

Definitions

• the invention relates to a device for fixing a bicycle stem to a fork pivot, comprising means for clamping the stem on the pivot.
• brackets surround the cylindrical outer wall of the pivot and are locked by tightening on the pivot unlike brackets, of an older type, fixed by an expander which is blocked inside the cylindrical wall of the pivot.
• the stem must include means for holding and blocking the handlebars.
• the pivot clamping means generally comprise two semi-cylindrical parts provided at the rear of the gallows, separated by a vertical slot, and provided with ears protruding rearwardly traversed by screws. Tightening.
• the slot decreases the resistance of the rear part of the stem, and the protruding ears can be a source of attachment.
• the device for fixing a bicycle stem to a fork pivot comprising a tubular part projecting forward
• the fixing device comprising means for clamping the stem to the pivot
• the rear end of the tubular part is integral with a sleeve in which the pivot of the fork, and that the clamping means of the stem are arranged to simultaneously carry out a fixing by clamping the handlebar to the stem.
• the clamping means of the stem comprise a first stop means against a zone of the pivot opposite to the handlebar; second stop means against a zone of the handlebar opposite the pivot; a support means on the stem for the handlebars; and connecting means of adjustable length between the two stop means for exerting the tightening.
• the first stop means comprises a clamping part forming a loop surrounding the pivot, inside the stem, this loop bearing against the zone of the pivot opposite the handlebar.
• the loop may have an elongated shape comprising a part that is substantially i-cylindrical, bearing against the pivot, extended by two substantially straight converging branches joined at their end, in particular by a transverse plate.
• the second stop means is formed by a stem head matching the handlebar area opposite the pivot and bearing against this area.
• the connecting means of adjustable length between the two stop means comprise at least one screw bearing against one of the two stop means, and a nut pressing against the other of the two stop means, the screw cooperating with 1 nut to ensure the simultaneous tightening of the pivot and the handlebar.
• the invention also relates to a bicycle stem suitable for being fixed by a device as defined above.
• the stem includes, at the rear, a sleeve with an entirely closed external contour, the internal diameter of which is adjusted to the external diameter of the pivot.
• a groove is provided on the inner wall of this sleeve to allow the semi-cylindrical part of the loop of the first stop means to be housed there.
• the stem sleeve is integral with a tubular part projecting forwards, this tubular part comprising, at its front end, the handlebar support means comprising a semi-cylindrical bearing surface open towards the front, provided for each side of the protruding part.
• the stem head has a substantially semi-cylindrical shape, crossed by two holes for the passage of the fixing screws which engage inside the stem, the axes of the fixing screws being located in a plane which passes through the of the stem sleeve.
• the stem is advantageously made of composite material.
• composite material is meant a material consisting of fibers with high mechanical strength, in particular carbon fibers and / or glass fibers, generally in the form of sheets and which, during a molding operation , are embedded in an epoxy or polyester type resin, or equivalent, which hardens.
• the stem can be mounted on a metal pivot or on a composite material pivot.
• a plug engaged in the hollow part of the pivot and extending to the level of the first stop means.
• Figure 1 of these drawings is a view in perspective of a gallows equipped with a fixing device according to one invention.
• Figure 2 is a longitudinal vertical section of the bracket with fixing device, on a larger scale.
• Figure 3 is a perspective in longitudinal section of the bracket from which the fixing device has been removed.
• Figure 4 is a perspective view of the clamping piece forming the first stop means provided with nuts.
• Figure 5 is a perspective view from another angle, on a different scale, of a variant of the clamping part without the nuts.
• Figure 6 finally, is a perspective view of the stem head for tightening the handlebars.
• a bicycle stem 1 comprising a tubular part 2 projecting forward.
• the rear end of the part 2 is integral with a sleeve 3 whose geometric axis forms, with that of the tubular part 2, a relatively large angle A (FIG. 2), generally greater than 60 °.
• the sleeve 3 has a continuous outer peripheral surface.
• a fork pivot 4 diagrammatically represented, is engaged in the sleeve 3 whose internal diameter is equal, to within manufacturing tolerances, to the external diameter of the pivot 4.
• the pivot 4 is integral with the front fork 5 of the bicycle and is rotatably mounted, by a set of stops and steering bearings in the steering column 6 of the bicycle frame.
• a handlebar 7 makes it possible to control the orientation of the fork 5.
• the bracket 1 comprises clamping means S on the pivot 4. These clamping means S are arranged to simultaneously fix the bracket 1 on the pivot 4 and the handlebar 7 on the bracket 1.
• the clamping means S comprise: a first stop means 8 against a zone 9 of the pivot opposite to the handlebar 7; a second stop means 10 against a zone 11 of the handlebars opposite the pivot 4; a support means 12 (Fig.l) provided on the stem for the handlebars, and connecting means L of adjustable length between the two stop means 8 and 10 to ensure the tightening.
• the first stop means 8 comprises a clamping piece 13, clearly visible in Fig.4 and Fig.5, forming an elongated loop, which surrounds the pivot 4.
• the loop 13 has a substantially semi-cylindrical part 14 bearing against the zone 9 of the pivot, this part 14 being extended by two converging straight branches 15a, 15b joined at their ends by a transverse plate 16 of rectangular shape whose large dimension is oriented vertically.
• the height H of the plate 16 can be substantially equal to twice the width h of the branches 15a, 15b.
• the connection of the branches 15a, 15b to the plate 16 is ensured by trapezoidal cheeks 17 ensuring the transition between the branches and the plate.
• the part 13 can be obtained by cutting a sheet which is then bent into the desired shape.
• the plate 16 can be formed by the superposition of two elementary plates 16a, 16b (Fig.4) provided at each end of the branches 15a, 15b and folded at right angles to each other. As a variant (FIG. 5) the plate 16 is in one piece, integral with the vertical end edges of the branches 15a, 15b. Oblong openings 18, separated by areas of material 19, can be provided along the middle line of the part 13 in order to lighten it.
• Part 14 follows zone 9 of pivot 4, while the mean line of branches 15a, 15b is oriented along the longitudinal axis of part 2 of the bracket.
• the rear generator of the part 14 forms with the mean line of the branches 15a, 15b an angle equal to the angle A.
• the inner wall of the sleeve 3 of the bracket comprises, at the level of the loop 13, a groove 20 located in the rear semi-cylindrical part of the sleeve 3 to receive the thickness of the part 14 of the loop 13.
• the second stop means 10 is formed by a stem head 21 clearly visible in Fig.6.
• This head 21 is formed by a sort of substantially semi-cylindrical shell covering the area 11 of the handlebar.
• the head 21 has two protrusions 22, 23.
• the protrusions 22, 23 are crossed by holes 22a, 23a located beyond the outline of the handlebars and whose axes are inclined to converge towards the pivot
• the axes of the holes 22a, 23a are located, when the head 21 is in place, in the plane defined by the geometric axis of the sleeve 3 and the geometric axis of the part
• the stem head 21 comprise two nuts 24, 25 bearing against the plate 16 of the clamping piece 13, and two screws 26, 27 passing through the stem head 21 and bearing by their heads, in particular spherical, against seats 22b, 23b.
• the transverse plate 16, or each elementary plate 16a, 16b, is crossed by two holes Ta, Tb whose centers are located on a straight line perpendicular to the mean plane of the loop 13.
• Each nut 24, 25 comprises an elongated tubular part 24a, 25a with thread, which passes through the respective holes Ta, Tb.
• the parts 24a, 25a, at their end facing the pivot 4, are provided with a head 24b, 25b of larger outside diameter coming into abutment against the plate 16.
• the annular faces of the heads 24b, 25b bearing against the plate 16 are suitably inclined relative to the geometric axis of the tubular parts 24a, 25a so as to be in contact with the plate 16 while these tubular parts 24a, 25a are oriented in the direction of holes 22a, 23a of the gallows head.
• the nuts 24.25 can be used to lock the two elementary plates 16a, 16b through which the parts 24a, 25a pass.
• the support means 12 of the stem for the handlebar comprises, on either side of the tubular part 2 of the stem, a semi-cylindrical bearing 12a, 12b open towards the front and provided respectively on each side of the projecting part 2.
• the geometric axis of the bearing surfaces 12a, 12b is orthogonal to that of the tubular part 2.
• Each protrusion P corresponds to an inclined groove, located inside the stem, for the passage of one of the screws 26, 27.
• the bracket 1 can be made of metal, in particular of light alloy.
• the bracket 1 is made of composite material.
• the pivot 4 can be a metallic pivot or a pivot made of composite material.
• a plug 28 is generally provided, schematically represented in FIG. 2, which is engaged in the hollow part of the pivot 4 and crosses the tightening zone corresponding to the loop 13 in order to increase the compressive strength of the pivot 4.
• the nuts 24, 25 are mounted in the holes Ta, Tb of the plate 16.
• the bracket head 21, crossed by the screws 26 and 27, is assembled to the tightening loop 13 by screwing the screws 26 and 27 into the nuts 24 and 25.
• the handlebar 7 is then engaged between the screws 26 and 27, behind the stem head 21.
• the height of the stem on the pivot 4 is adjusted according to the morphology of the cyclist.
• the pivot 4 is generally cut at the height thus adjusted.
• the plug 28 is placed inside the pivot 4, at the level of the tightening loop 13.
• the fixing device of the invention is housed essentially for the interior of the bracket and makes it possible to produce a sleeve 3 fully closed with a continuous surface, devoid of a slot.
• the strength and aesthetics of the stem are improved.
• the assembly operations of the stem, the pivot and the handlebars are simple and quick to perform.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Steering Devices For Bicycles And Motorcycles (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9532911

Family Applications (1)

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Citations (1)

Family Cites Families (5)

• 1998
  • 1998-11-19 FR FR9814535A patent/FR2786155B1/fr not_active Expired - Fee Related
• 1999
  • 1999-11-12 WO PCT/FR1999/002776 patent/WO2000030923A1/fr not_active Ceased
  • 1999-11-12 EP EP99972594A patent/EP1131244A1/de not_active Withdrawn

Patent Citations (1)

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