WO2024013659A1

WO2024013659A1 - Stem provided with means for vibration dissipation

Info

Publication number: WO2024013659A1
Application number: PCT/IB2023/057104
Authority: WO
Inventors: Andrea AGAZZINI
Original assignee: Agazzini & C. S.N.C.
Priority date: 2022-07-15
Filing date: 2023-07-11
Publication date: 2024-01-18

Abstract

A stem of a bicycle (1) comprising a central body (3) provided with means (2) for connecting to the fork (10, 10') of the bicycle (1), a clamp (4) for retaining the handlebar (11), and vibration dissipation means. The central body (3) has a joint seat (34) in which a joint terminal (44) provided on the clamp (4) is engaged, so that the clamp (4) is linked to oscillate with the central body (3). The vibration dissipation means comprise one or more base front protrusions (32) provided on the central body (3) and protruding beyond the handlebar (11) and one or more support front protrusions (42) provided on the clamp (4) and protruding beyond the handlebar (11), the base protrusions (32) and the support protrusions (42) being vertically aligned with each other and one or more shock-absorbing elements (5) being provided between the base protrusions (32) and the support protrusions (42).

Description

Stem provided with means for vibration dissipation

The present invention is related to devices for the connection of the handlebar to the front suspension system and to the bicycle frame and more particularly concerns a new stem system that integrates therein a damping system for the vibrations transmitted from the front wheel to the handlebar-user system.

From now on we will identify this system with the term "stem".

The present invention relates to a stem for a bicycle, which stem comprises a central body provided with means for connecting to the fork of the bicycle, with a handlebar retaining clamp, and with means for vibration dissipation.

The stem is the element that connects the handlebar to the fork/frame system of a bicycle.

This system, in the most modern bicycles, is a crucial element that, through its geometry, has made it possible to substantially improve the efficiency of the bicycle and the riding comfort, and has also allowed the riding technique to be modified over the years.

Whether for road bicycles or off-road bicycles, the stem is an element of crucial importance as an element to complete the overall bicycle system.

Depending on its shape and length (which varies between the various road and off-road disciplines), the stem (vertical system) transfers the force received from the support imparted by the user's arms through the handlebar to the front suspension/frame (horizontal system), also transferring the torque resulting from the 'steering' by the user's arms to the front wheel.

The stem is normally made up of the main parts:

- the central body, which with its various lengths and shapes distinguishes the final geometry that the handlebar will have with respect to the axis of the fork, or steering shaft, and the frame; - the front collar or clamp, which tightens the handlebar and links it to the central body;

- connection means to the fork of the bicycle, for example the rear collar, which wraps and tightens the axis of the fork so as to transfer the torque to it.

The rear collar constitutes a connection system called "ahead" or "threadless", to distinguish it from a threaded or "quill" stem, in which the central body has a rearward curve downwards with a threaded lower end to be inserted into a threaded steering shaft.

These parts are normally obtained through a central body that encloses the rear collar, while the front collar consists of a part removable by means of fixing screws, which allows the handlebar to be housed and subsequently fixed and tightened integrally with the central body.

The stem can also be read in the reverse way, i.e. with the function of supporting the weight of the user and discharging it from the handlebars onto the fork system and front wheel and then to the ground.

Traditional stems are usually made of metallic materials or their alloys (aluminium, titanium, etc.) and do not have any shock-absorbing elements inside them, except for stem systems for motorcycles, which provide solutions through attachments that connect the fork plate to the handlebar, interposing elastomeric elements between them.

However, these solutions are rarely used, since the shockabsorbing system is free to oscillate in all directions and not only towards the one necessary to absorb the shocks deriving from the fork axis, thus making the ride rather inaccurate.

Other stem systems for bicycles have been invented with shockabsorbing systems to replace the absence of a shock-absorbing fork (as in the cases of stems for gravel bicycles or road bicycles) while still little attention has been paid to "gravity" biking with enduro/downhill bicycles, where current standards require strong rigidity, low weight and above all a very close spacing (offset) between handlebar and fork tube (60/100mm in gravel/road bicycles; 40/50mm in gravity bicycles). Recently, companies involved in motocross have also emerged, which have prototyped stems for MTBs that incorporate inside them two hydraulic pistons, similar to two rear shock absorbers for MTBs, with air inflation, which allow vertical damping of the forces with the sliding of the chainstays in the blades. However, this solution is very expensive and heavy, and unsuitable for guaranteeing the right rigidity when the user wants to "pump" the bicycle with their arms, that is, to impart force on the handlebar downwards to compress and subsequently extend the fork in order to lighten the loads on the front. These systems, in addition to an increased weight, are affected by a reduced sensitivity at the beginning of the compression. The shock absorber, in fact, is not able to dampen small vibrations, since, especially in the most modern air shock absorbers, the hydraulic and mechanical seals create a modest initial force that must be "overcome" in order to obtain the operation of the system.

In traditional bicycle stems, the connection type has a very high degree of rigidity and transmits to the shock absorber/frame/user system every slightest vibration arising from the route taken (road or off-road).

This stiffness also results in a sudden series of small high- frequency vibrations that, when viewed in slow motion, continuously create small load decreases on the front wheel. The damping of these vibrations is in this case entrusted only to the damped fork (if present) and to the tyre.

The damped fork is not able to dampen all these small vibrations, since, especially in the most modern air shock absorbers, the hydraulic and mechanical seals create a modest initial force that must be "overcome" to obtain the operation of the system.

This means that a conventional stem system with high stiffness transmits all vibrations at high frequencies to the bicycle-user system on the one hand and a series of vibrations to the wheel on the other hand, which reduce comfort, cornering traction and suspension effectiveness.

Known solutions to this problem rely exclusively on pneumatic shock absorbers, which the industry requires to be made with the best sliding rails to optimise the response to high vibrations, incurring ever higher manufacturing costs and still achieving questionable effectiveness.

The damped stems currently known have the function of supplementing the lack of the front suspension and, for the bicycles suitable for the aforementioned gravity disciplines, there is an unmet need for a more sophisticated system that combines the intrinsic characteristics of rigidity, damping of vibrations and geometries to suit the components of the sector.

The currently known damped stems are made by decomposing the central body into two sections, connected together by a transverse pin that allows it to oscillate, and an elastomer or spring placed at the base of one of them, which, acting as a limit switch, limits its oscillation and causes vertical shock-absorbing.

CN 206 856 904 II discloses a bicycle handlebar shock absorber structure that utilizes a shock-absorbing component between the handle and the front fork riser tube. A part pressed on the base of the grip presses on the shock-absorbing component reducing shocks.

Document EP 3 597 519 A1 discloses a shock-absorbing device including two modules, at least one joint component and one shockabsorbing component. The shock-absorbing component is located between the two modules. When the two modules rotate with respect to each other, the force between the two modules is damped by the shockabsorbing component.

US 2006/260432 A1 discloses a stem comprising a shockabsorbing cylinder.

The document US 5 253 544 A discloses a bicycle handlebar assembly comprising a damping element interposed between two connection elements.

The technical problem that the present invention aims to solve is how to free the tyre, or the system of the tyre and damped fork, from being the only element capable of attenuating the horizontal vibrations caused by the impacts with the obstacles resulting from the use of the bicycle offroad, and to make it work synergistically with the stem system. The present invention aims at overcoming the drawbacks of the systems known from the state of the art and at achieving the aforementioned purposes with a stem as disclosed at the beginning, in which the central body has a joint seat in which a joint terminal provided on the clamp is engaged, in such a way that the clamp is linked to oscillate with the central body. The vibration dissipation means includes one or more base front protrusions provided on the central body and protruding beyond the handlebar and one or more support front protrusions provided on the clamp and protruding beyond the handlebar, the base protrusions and the support protrusions being vertically aligned with each other and one or more shock-absorbing elements being provided between the base protrusions and the support protrusions.

In one embodiment, the shock-absorbing elements are made of elastomeric material.

Thus an "active" stem is obtained that can be advantageously adapted to the MTB enduro and downhill disciplines and that allows the damping of the highest vibration frequencies, leaving the damped tyre and/or fork the task of managing the medium-low frequencies.

This system is particularly cost-effective and allows great improvements in comfort and performance with an easy-to-use technical solution that can be used on any existing type of bicycle.

This "active" stem not only improves riding comfort, but also safety and performance, as the attenuation of vibrations transmitted to the wheel significantly improves the grip of the wheel on the ground, resulting in improved traction in both cornering and braking with a corresponding increase in safety.

The ride feel is that of using a very low pressure front tyre, which better absorbs the roughness of the ground and has much more traction especially on rough or slippery terrain, without however having all the negative effects that riding on low pressure tyres can bring, i.e. poor driving precision, poor cornering due to the deformation of the tyre walls, danger of damage to the rim due to possible impact with the ground, difficulty coasting due to rolling friction and relative decrease in pedalling efficiency, etc.

The actual damping of vibrations is entrusted to the elements made of elastomeric material, which can be made in the hardness required by the intended use of the bicycle as well as the weight of the user.

In one embodiment the joint seat and the joint terminal are configured such that the handlebar retaining clamp is linked to oscillate with the central body about a horizontal axis and perpendicular to the anteroposterior axis of the bicycle.

The present invention therefore does not provide for a decomposition of the central body into several articulated segments or the insertion of further sliding guides, but rather provides a floating front clamp that allows freedom of oscillation in the direction parallel to the stress imparted between the user and the fork, so as to reduce stresses and vibrations on the handlebar, without compromising its sensitivity and riding safety.

According to one improvement, the joint seat has two recesses facing each other and suitable for housing two bearings, and the joint terminal has at least one joint pin configured to engage in said bearings.

The bearings are preferably roller bearings, but may be ball bearings, bushings, or other bearings.

The movement of the clamp with respect to the central body is constrained by the joint which, thanks to the presence of the bearings, makes the clamp an oscillating member with optimized sensitivity, allowing it to rotate inside the central body without any friction. The elements made of elastomeric material therefore constitute a damping system interposed between the clamp and the central body, which in this solution do not constitute a stem with a single fixed body, but an oscillating system by means of a pin on bearings.

In one exemplary embodiment, the central body in an intermediate zone between the base front protrusions and the means of connection to the fork is provided at the top with a recess housing the clamp retaining the handlebar. The shape of the central body is therefore adapted to house the front handlebar retaining clamp therein, thus drastically reducing the space required for operation of the system, while allowing the offset centre distances to be kept very low, and making it possible to create two main variants respectively dedicated to enduro cycling and downhill cycling, disclosed in detail below.

The "active" stem can be installed on any bicycle and its installation does not affect either the total weight or the final geometry of the bicycle, since it can be made in the desired geometry and can be adapted to different types of forks.

According to one embodiment, the base protrusions and the support protrusions have, in their respective opposite faces, recesses for housing the shock-absorbing elements.

In one embodiment, the base protrusions and the support protrusions have through holes for engagement of low-torque clamping screws.

These clamping screws allow a compression of the shock absorber elements in the direction of mutual approach of the base protrusions and the support protrusions, while constituting a limit stop in the direction of their removal.

The compression of the shock-absorbing elements takes place in the front and near area between the handlebar retaining clamp and the rigid central body, pursuing both a function of transmission of loads and damping of vibrations using the deformation capacity of the material.

For proper functionality, the elastomeric material must ensure proper continuity with its support and this continuity can be achieved by means of the said low-torque clamping of the front screws that make it integral with the central body, even in the event that the user pulls the handlebar towards themself with force, or in the event of a fall.

The system, with its kinematic mechanism, therefore makes it possible to make the handlebar completely rigid when subjected to vertical forces or when the user pulls on it, and to accommodate horizontal forces instead, as if the user could release the impact imparted by the front wheel with a modest movement of the bicycle towards the rear, thus simulating a minimal movement in the rearward direction of the wheel, as well as in the direction of the fork, as is the case with the already well- known rear linkage systems, which, in addition to the classic upward movement, also allow a slight retraction of the wheel to better surmount obstacles.

The system does not involve any geometric variation in the overall system and therefore does not cause any possible interference with the frame or other elements of the bicycle.

The active system, during operation, provides for a compression of the shock-absorbing elastomer part, due to the force imparted by the handlebar on it, in the only horizontal direction of the forces coming from the front wheel and the fork.

In normal situations the elastomeric system is inserted at the front on two joint points, but may vary position and number according to the type of shape and geometry required for the stem.

Depending on the degree of damping required, the elastomeric system can be calibrated accordingly, varying its stiffness value (Shore), obtaining a targeted system customization for each user.

The active stem can be used on any type of bicycle, whether for amateur use, urban transport or racing.

The system has been designed to allow easy replacement of the shock-absorbing elements made of elastomeric material in case of damage and/or wear.

While the invention is subject to various modifications and alternative constructions, some preferred embodiments have been shown in the drawings and disclosed in detail. It must be understood, however, that there is no intention to limit the invention to the specific form/geometry of embodiment illustrated, but, on the contrary, it is intended to cover all modifications, alternative constructions, and equivalents that fall within the scope of the invention as defined in the claims, in order to adapt to the shape and geometry requirements of the market. These and other features and advantages of the present invention will become clearer from the following description of some non-limiting examples illustrated in the accompanying drawings, wherein:

Fig. 1 illustrates a first embodiment of the stem on a single-plate fork bicycle;

Fig. 2 shows an exploded detail view of the first embodiment;

Fig. 3 shows an assembled detail view of the first embodiment;

Fig. 4 illustrates a second embodiment of the stem on a bicycle with a double-plate fork;

Fig. 5 shows an assembled detail view of the second embodiment.

The figures illustrate exemplary embodiments of the stem in accordance with the present invention. The stem connects a handlebar 11 to a bicycle 1 . For this purpose, the stem comprises a central body 3 provided with connection means 2 to the fork 10 of the bicycle 1 and a clamp 4 for retaining the handlebar 11 .

In the first embodiment of Figures 1 , 2 and 3, the bicycle 1 is provided with a damped front fork 10 of the single-plate type, typical of enduro MTBs.

As can be seen in Figures 2 and 3, the single-plate fork 10 is provided at the top with a steering shaft 12, with which it engages in the frame of the bicycle 1. The steering shaft 12 protrudes above the frame and engages with the stem by means of said connection means 2, which in this first embodiment variant comprise a rear clamp 20 adapted to be tightened around the steering shaft 12 by means of screws, not illustrated in the figures.

The clamp 4 for retaining the handlebar 11 is divided into two parts, a lower part 40 and an upper part 41 , which parts 40 and 41 can be coupled together and clamped around a central part of the handlebar 11 to hold it by means of clamping screws, namely four screws, not shown in the figures.

The central body 3 has a joint seat 34 in which is engaged a joint terminal 44 provided on the clamp 4 for retaining the handlebar 11 . In this way, in the assembled condition, the clamp 4 is linked to oscillate with the central body 3. The joint seat 34 and the joint terminal 44 are configured such that the clamp 4 retaining the handlebar 11 is linked to oscillate with the central body 3 about a horizontal axis and perpendicular to the anteroposterior axis of the bicycle 1 . The joint seat 34 has two recesses 31 facing each other and suitable for housing two bearings, not illustrated in the figures. The joint terminal 44 is constituted by the rear parts, along the anteroposterior axis of the bicycle 1 , of the two parts 40 and 41 constituting the clamp 4, in coupled condition with each other. The joint terminal has a through hole formed by the coupling of two grooves 43 provided on the two parts 40 and 41 that constitute the clamp 4. In this through hole is housed a joint pin suitable for protruding beyond the hole at its opposite ends and for engaging with said ends in said bearings. The joint pin is not shown in the figures. The central body 3 is provided with holes 33 near the joint seat 34 for inserting the joint pin into position.

The central body 3, in an intermediate zone at the position of the handlebar 11 , is provided at the top with a recess 30 housing the clamp 4 retaining the handlebar 11 .

The stem according to the invention includes vibration dissipation means comprising two base front protrusions 32 provided on the central body 3 and protruding beyond the handlebar 11 and two support front protrusions 42 provided on the clamp 4 for retaining the handlebar 11 and protruding beyond the handlebar 11. The base protrusions 32 and the support protrusions 42 are vertically aligned with each other and a shockabsorbing element 5 is provided between each base protrusion 32 and the respective support protrusion 42. In this way, two frontal zones are formed along the anteroposterior axis of the bicycle for damping the vibrations coming from the front fork 10. Any number of protrusions and shock-absorbing elements can be provided, with geometries also different from what is illustrated in the figures.

The shock-absorbing elements 5 are advantageously made of elastomeric material, preferably of polyurethane elastomer.

The actual damping of vibrations on the front of the bicycle 1 at higher frequencies is therefore entrusted to the shock-absorbing elements 5, which can be made according to the hardness required by the intended use of the bicycle 1 as well as the weight of the user.

Depending on the degree of damping required, moreover, the shock-absorbing elements 5 can be calibrated by varying their stiffness value, obtaining a targeted system customization for each user.

The base protrusions 32 and the support protrusions 42 have, in their respective opposite faces, recesses for housing the shock-absorbing elements 5. The recesses facing each other thus form housing seats for the shock-absorbing elements 5. Base protrusions 32 and support protrusions 42 have through holes for engagement of low-torque clamping screws, not shown in the figures.

The means for dissipating vibrations are therefore such as to allow easy replacement of the shock-absorbing elements 5 in the event of damage and/or wear.

The shock-absorbing elements 5 each preferably have a profile that is circular and perforated in the centre, so as to allow the passage of said clamping screws.

The shock-absorbing elements 5 may, however, be constituted by an elliptical profile bush or by a flat or arcuate profile element. The size of the shock-absorbing elements 5 and therefore their support surface can be varied at the design stage according to the intended use or loads involved in the force system.

The second embodiment variant shown in Figures 4 and 5 comprises all the features disclosed above for the other figures, and differs from the first embodiment variant solely by the connection means of the central body 3 to the bicycle fork 10'. In this embodiment, the fork 10' is of the double-plate type, typical for downhill MTBs.

In this case, the connection means consist of two arms 21 integral with the central body 3 and adapted to the "direct-mount" standard or to the direct connection through threaded screws to the upper plate of the double plate fork 10'. The invention does not involve any geometric variation in the front suspension system and therefore does not cause any possible interference with the frame or other elements of the bicycle 1 .

The invention can be used on any type of bicycle, whether for amateur use, urban transport or racing.

Claims

1. A stem of a bicycle (1 ) comprising a central body (3) provided with means (2) for connecting to the fork (10, 10') of the bicycle (1 ), a clamp (4) for retaining the handlebar (11 ), and vibration dissipation means, characterized in that the central body (3) has a joint seat (34) in which a joint terminal (44) provided on the clamp (4) is engaged, so that the clamp (4) is linked to oscillate with the central body (3), and the vibration dissipation means comprise one or more base front protrusions (32) provided on the central body (3) and protruding beyond the handlebar (11 ) and one or more support front protrusions (42) provided on the clamp (4) and protruding beyond the handlebar (11 ), the base protrusions (32) and the support protrusions (42) being vertically aligned with each other and one or more shock-absorbing elements (5) being provided between the base protrusions (32) and the support protrusions (42).

2. The stem according to claim 1 , wherein the shock-absorbing elements (5) are made of elastomeric material.

3. The stem according to claim 1 or 2, wherein the joint seat (34) and the joint terminal (44) are configured in such a way that the clamp (4) retaining the handlebar (11 ) is linked to oscillate with the central body (3) about a horizontal axis and perpendicular to the anteroposterior axis of the bicycle (1 ).

4. The stem according to claim 3, wherein the joint seat (34) has two recesses (31 ) facing each other and suitable for housing two bearings, and the joint terminal (44) has at least one joint pin configured to engage said bearings.

5. The stem according to one or more of the preceding claims, wherein the central body (3) in an intermediate zone between the base front protrusions (32) and the connection means (2) to the fork (10, 10') is provided above with a recess (30) housing the clamp (4) retaining the handlebar (11 ).

6. The stem (11 ) according to one or more of the preceding claims, wherein the base protrusions (32) and the support protrusions (42) have, on their opposite faces, recesses for housing the shock-absorbing elements (5).

7. The stem (11 ) according to one or more of the preceding claims, wherein the base protrusions (32) and the support protrusions (42) have through holes for low-torque engagement of the clamping screws.