PROP STAND POSITION DETECTION AND ALERTING DEVICE
FIELD OF THE INVENTION

[0001] The present invention relates to a prop stand position detection and alerting device and more particularly to a mechanism capable of detecting the position of a prop stand and alerting the rider in a two wheeled vehicle.

BACKGROUND OF THE INVENTION

[0002] A two wheeled vehicle, such as a motorcycle, is generally provided with atleast two supporting members, namely a centre stand and a prop stand, which support the vehicle body in a standing state when the vehicle is non-operational. The centre stand is operated when the vehicle is parked for long durations whereas the prop stand is utilized when the vehicle is to be parked temporarily for a short period of time. Both the supporting members are pivotally attached to a frame of the vehicle.

[0003] When the vehicle is specifically parked using a prop stand, both the wheels of the vehicle are in contact with the ground. Often a rider riding such vehicle forgets to retract the prop stand used previously and starts riding it with the prop stand in an operative position. There is thus a likely possibility of prop stand contacting the ground while the motorcycle is moving or turning which may cause jerks or spins. It may also lead to loss of control of the motorcycle by the rider and hence may cause fatal accidents.

[0004] Several devices or mechanisms capable of detecting the position of a prop stand have been previously proposed. They alert the rider either through an audible signal or by a display signal, if the prop stand is in operative position. Such devices are responsive to a change in position of the prop stand. However, there are several problems associated with them. A conventional prop stand position detection device in a motorcycle is mounted on the same bracket as the prop stand due to which it is proximate to the ground. Consequently, such device in a motorcycle with a lower ground clearance is prone to frequent mud and water splash during the rainy season or on flooded roads and even during servicing the vehicle. The device may thus become unresponsive due to which the positioning of such a device becomes very crucial. Any clog or block by layering of undesirable foreign matter including mud, dust, wet soil or the like, may also lead to its unresponsiveness.

[0005] Further, a prop stand is generally spring-loaded. When the rider pushes the prop stand to its operative position from a withdrawn (inoperative) position, the prop stand is released quickly owing to the preloaded spring. Hence a prop stand position detection device in direct contact with the prop stand may break or fail frequently, if it is not suitably cushioned, thus leading to a reduction in its durability. Hence, the present invention is directed to overcoming one or more problems as set forth above.

[0006] It is therefore one of the objectives of the present subject matter to provide a mechanism capable of detecting the position of a prop stand of a two wheeled vehicle and alert a rider of the vehicle when the prop stand is in operative position and the vehicle ignition is on. It is also an object of the present subject matter to provide a simple, reliable, durable and flexible prop stand detection and alerting device which can absorb excess impact or shock loads on the device and prevent its unwanted actuation.

SUMMARY OF THE INVENTION
[0007] To this end, the present subject matter discloses a position detection and alerting mechanism, to detect the undesirable position of a prop stand of a two wheeled vehicle and alert a rider of the vehicle, comprising: a rotatable rotor member with at least one movable electrode disposed on a preloaded movable holder on the rotor member, a static means for covering the rotor member with at least one fixed electrode, and a dust seal.

[0008] According to an aspect of the present subject matter, the position detection and alerting mechanism is mechanically connected to the prop stand of the two wheeled vehicle and electrically connected to an audible means, or a display means, or an audible and a display means.

[0009] According to another aspect of the present subject matter, the prop stand is pivotable about a mounting bracket through a pivot bolt and defines an operative and a withdrawn position.

[00010] According to yet another aspect of the present subject matter, when the prop stand is in the withdrawn position, the movable electrode of the rotor member is not in contact with the fixed electrode of the said means and the mechanism is non-functional, and when the prop stand is in the operative position and the vehicle ignition is on, the movable electrode of the rotor member makes a contact with the fixed electrode of the said means at an angle equivalent to a prop stand operating angle less a preload angle, and the mechanism is actuated. The excess rotation is absorbed by the flexible movable electrode holder and the output signal of this mechanism alerts the rider in the form of an audible signal or by a display signal or both.

[00011] According to another aspect of the present subject matter, the dust seal is provided forwardly to the rotor member to prevent the entry of undesirable foreign matter including mud and water into the mechanism and the dust seal is circumferentially in contact with a surface of the prop stand.

[00012] According to another aspect of the present subject matter, the position detection and alerting mechanism can be used with any two wheeled vehicle including a motorcycle, moped and a scooter type motorcycle.

[00013] According to an aspect of the present subject matter, the position detection and alerting mechanism may be used with a prop stand, wherein the prop stand is manually or electrically driven.

[00014] The foregoing objectives and summary provide only a brief introduction to the present subject matter. To fully appreciate these and other objects of the present subject matter as well as the subject matter itself, all of which will become apparent to those skilled in the art, the ensuing detailed description of the subject matter and the claims should be read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[00015] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description, appended claims and accompanying drawings where:

Figure 1 shows a front view of a typical two wheeled vehicle in the form of a motorcycle capable of accommodating the present subject matter.

Figure 2 shows a perspective view of a frame of the vehicle incorporating a position detection and alerting mechanism according to the present subject matter.

Figure 3 shows a front view of a prop stand assembly connected to the vehicle frame.

Figure 4 shows an exploded view of the position detection and alerting mechanism according to the present subject matter.

Figure 5 shows a left side view of the position detection and alerting mechanism with the prop stand according to the present subject matter.

Figure 6 shows a right side view of the position detection and alerting mechanism according to the present subject matter.

Figure 7 shows a rear view of the position detection and alerting mechanism integrated with the prop stand according to the present subject matter.

Figure 8 shows a sectional rear view to illustrate the functioning of the position detection and alerting mechanism when the prop stand is in the withdrawn position.

Figure 9 shows a sectional rear view to illustrate the functioning of the position detection and alerting mechanism when the prop stand is in the operative position.

DETAILED DESCRIPTION OF THE INVENTION

[00016] The subject matter described herein relates to a mechanism capable of detecting the position of a prop stand in a two wheeled vehicle and alerting the rider of the vehicle if the prop stand is in an operative position and the vehicle ignition is on.

[00017] It is to be noted that the present subject matter is not dependent on the type of a two wheeled vehicle and therefore is equally workable with any two wheeled vehicle having a prop stand, including a motorcycle, a scooter type motorcycle or a moped. The position detection and alerting mechanism may be used with a manually driven or an electrically driven prop stand with ease. Further the drawings have been represented along an F-R axis and an X-Y axis. The "F", "R", "X" and "Y" respectively refers to "front", "rear", "left" and "right" directions as seen in a state of observing the vehicle as an onlooker. Furthermore, a longitudinal axis refers to a front to rear axis relative to the vehicle, while a lateral axis refers generally to a side to side, or left to right axis relative to the vehicle. Various other features and embodiments of the mechanism according to the present invention here will be discernible from the following further description thereof, set out hereunder.

[00018] The position detection and alerting mechanism is now described in detail in connection with the rendered figures 1-9. The detailed explanation of the constitution of parts other than the subject matter which constitutes an essential part has been omitted at suitable places. Figure 1 shows a front view of a typical two wheeled vehicle in the form of a motorcycle capable of accommodating the present subject matter. The vehicle M comprises a body frame assembly made up of a number of tubes welded together. The vehicle M has a steerable front wheel 11 and a driven rear wheel 12. The body frame primarily includes a head pipe 1 disposed at a front end of the body frame, a main tube running across the longitudinal axis of the vehicle M and enclosed by several vehicle components, and a down tube 2. A front fork 3 may be connected to the head pipe 1 through any known type of suspension system for the front wheel and rotatably carries the front wheel 11. The head pipe 1 supports a steering shaft (not shown) disposed inside the head pipe 1. The upper and lower ends of the steering shaft are fixed on an upper bracket and an under bracket (both not shown). The front end of the main tube and an upper end of the down tube 2 are connected to the head pipe 1. The down tube 2 extends obliquely downward in front of an engine 15 from the head pipe 1 whereas the main tube extends rearward from the front end thereof. [00019] A front fender 4 is provided below the under bracket to avoid the vehicle and its occupants from being splashed with mud. A fuel tank 5 is disposed above the main tube for storing the fuel for propelling the vehicle M. A seat 6 for a driver and a pillion is further provided, with the said seat 6 being placed behind the fuel tank 5 and rearwardly of the main tube.

[00020] The left portion of the vehicle placed forward to the fuel tank 5 comprises of a headlamp assembly, the headlamp assembly further comprising a headlamp 8 and a visor 7 placed forward to a handlebar assembly. The handle bar assembly further comprises of a handle bar 9 extending transversely to the vehicle and several control switches for various vehicle operations. [00021] The said vehicle M is powered by the internal combustion engine 15 disposed below the main tube and supported by the down tube 2. The engine may be liquid-cooled or air-cooled. Drive force output from the engine 15 is transmitted to the rear wheel 12 through a transmission system. [00022] Further, the rear wheel 12 revolves about a sprocket splined shaft (or central axle) 13. The axle 13 is supported at each end by a swing arm 14, the swing arm in turn pivotally connected to the body frame of the vehicle M by a suspension 17. Generally a saddle type vehicle may use any of the two arrangements for rear suspensions, namely dual suspension and mono suspension. However the present vehicle is exemplified through a dual suspension system. In the description, the suspension present only on one side of the rear wheel is described. The other side would incorporate an identical suspension in the dual suspension system. Both suspensions in the suspension system are fixed at their upper ends to the vehicle frame and at their lower ends to the swing arm 14.

[00023] Atleast two supporting members, namely a centre stand 18 and a prop stand 20, are provided at a front lower portion of the vehicle which support the vehicle in a standing state when the vehicle is non-operational. The centre stand 18 is operated when the vehicle is parked for long durations whereas the prop stand 20 is utilized when the vehicle is to be parked temporarily for a short period of time. The centre stand 18 as well as the prop stand 20 are pivotally attached to the body frame of the vehicle M.

[00024] Figure 3 shows a front view of the prop stand assembly connected to the down pipe 2 of the body frame of the vehicle M. The prop stand assembly is configured to support the two wheeled vehicle during parking and largely includes a mounting bracket 21 connected to the lower end portion of the body frame of the vehicle, a pivot bolt 22 located forwardly to the mounting bracket 21 along the longitudinal axis, and the prop stand 20 pivotally attached to the mounting bracket 21 through the pivot bolt 22. The prop stand has a rear surface facing the centre stand 18 and a front surface facing opposite to the rear surface. The prop stand 20 and the pivot bolt 22 are turned together relative to the mounting bracket 21. [00025] Further, the prop stand 20 is spring loaded with the help of a stand spring 23 and generally functions in two positions; an operative position and a withdrawn (inoperative) position. It can pivot between the operating position at which the prop stand is in contact with the ground and withdrawn (inoperative) position at which it is approximately parallel to the ground. However, other angular positions are also possible. The rotation of the prop stand 20 towards the withdrawn position is restricted through a tapered portion 21a of the mounting bracket 21.

[00026] Figure 2 shows a perspective view of the body frame of the vehicle wherein the position detection and alerting mechanism 30 is mechanically connected to the said prop stand assembly according to the present subject matter. An exploded view of the position detection and alerting mechanism 30 is shown in Figure 4. The said mechanism 30 comprises a rotatable rotor member 31, a means for covering the rotor member 31, a movable holder 32 disposed in a slot of the rotor member 31, an insulating and sealing member 39 connected to a cavity 37 of the said means, and a dust seal 42. The detection and alert mechanism 30 is supported on a rear portion of the pivot bolt 22 wherein the rear portion is extended towards the centre stand 18.

[00027] According to an aspect of the present subject matter, the rotor member 31 may be polygonal in shape and has two ends, namely an open end 35b and a closed end 35a. The rotor member 31 is having a threaded portion inside of the open end 35b through which it is secured to the extended rear portion of the pivot bolt 22. The closed end 35a of the rotor member 31 is elongated in the middle forming an elongated portion 34 in such a way that the elongated portion 34 is projected out along R axis and has lesser diameter than rest of the closed end of the polygonal rotor member 31. The movable holder 32 is provided rearwardly to the closed end 35a of the rotor member 31 and is mounted on the elongated portion 34 of the rotor member 31 and has an upper and a lower portion. The upper portion of the movable holder 32 comprises atleast one movable electrode 33 whereas the lower portion of the movable holder 32 is secured in a slot, preferably of rectangular shape, the slot (not shown) being provided in the elongated portion 34 of the rotor member 31. Therefore the movable electrode 33 is disposed and attached to the movable holder 32.

[00028] Further, according to an aspect of the present subject matter, the said means for covering the rotor member 31 may be a body cover 36 largely cylindrical in shape with a hollow interior and having two circular co-axial ends with unlike diameters. One of the two ends, namely a hollow end 40b faces the rear surface of the prop stand 20 whereas the other end, covering end 40a faces rearwardly towards the R axis.

[00029] Furthermore, an insulating and sealing member 39 is provided in the mechanism which is connected with atleast one fixed electrode 38. A cavity 37 is provided in outer radial surface of the body cover 36 near the covering end 40a in such a way that the fixed electrode 38 is held in the cavity 37 of the said body cover through the insulating and sealing member 39. The fixed electrode 38 hangs towards the inner radial surface of the body cover 36 and faces the movable electrode 33 of the rotor member 31. According to an embodiment of the present subject matter, the insulating and sealing member 39 may contain two fixed electrodes spaced from each other and attached to the insulating and sealing member 39. Figure 6 shows a left side view of the mechanism 30 depicting the packing of the insulating and sealing member 39 into the cavity of the body cover 36. The insulating and sealing member 39 is in contact with the electric cables 43 which extend along the vehicle body frame and carry the output of the detection and alerting system 30. It is through these electric cables 43 that the position detection and alerting mechanism is electrically connected to an audible means, or a display means, or an audible and display means.

[00030] Further, a dust seal 42 is provided in the position detection and alerting mechanism 30 towards the hollow end 40b of the said body cover 36 and is circumferentially in contact with the rear surface of the prop stand 20 and the hollow end 40b of the body cover 36. The dust seal, on assembly of the position detection and alerting mechanism 30, seals the movable electrode of the rotor member and the fixed electrodes of the body cover from undesirable foreign matter including dust, mud, water and the like. Moreover, the dust seal 42 is preferably circular in shape and may be made of any material including rubber or plastic resin.

[00031] During assembly of the position detection and alerting mechanism 30, the rotor member 31 and the extended rear portion of the pivot bolt 22 are fully engulfed by the body cover 36 through the hollow end 40b in such a way that the rotor member 31 is not visible after the assembly. A rear view of the assembled position detection and alerting mechanism 30 is shown in Figure 7 whereas a right side view of the assembled position detection and alerting mechanism 30 is shown in Figure 5. Therefore, the body cover 36 helps to cover the rotor member 31 from undesirable foreign matter including water splash, mud, dust and the like. The elongated portion 34 of the rotor member 31 helps the rotor member 31 to fit into the body cover 36 without interfering with the fixed electrodes 38 present therein.

[00032] According to an aspect of the present subject matter, in the assembled state of the position detection and alerting mechanism, the movable electrode 33 on the rotor member 31 and the fixed electrode 38 in the cavity 37 of the body cover 36, are substantially planar and angularly disposed to each other. Preferably, the movable and the fixed electrodes may be perpendicular to each other. [00033] The rotor member 31 of the position detection and alerting mechanism 30 is secured, preferably fastened, to the extended rear portion of the pivot bolt 22 through the threaded portion inside the open end 35b of the rotor member 31. Thus the said mechanism 30 is mechanically connected to the prop stand 20 through the rotor member 31 and electrically connected to the audible means, or display means, or audible and display means through electric cables 43.

[00034] Further, the body cover 36 of the position detection and alerting mechanism 30 is supported by a holding bracket 41. In an embodiment of the present subject matter, the holding bracket 41 is L-shaped comprising a flat end 41b and an arc shaped end 41a, the latter largely semi-circular in shape and affixed to the outer radial portion of the said body cover 36, and the former in contact with a rear surface of the mounting bracket 21 facing the centre stand 20. In another embodiment of the present subject matter, the body cover may be held by a circular, flange-shaped holding bracket having four securing points. This holding bracket may be fastened to the prop stand having the corresponding securing points. Therefore a portion of the position detection and alerting mechanism 30, i.e. the rotor member 31 is supported on the extension of the pivot bolt 22 and another portion of the mechanism 30, i.e. the body cover 36 is supported by the holding bracket 41 which is in contact with the mounting bracket 21.
[00035] The working of the present subject matter is now described with the help of Figures 8 -9. As the prop stand 20 is pivotable about the mounting bracket 21 through the pivot bolt 22, the rotor member 31 rotates with the rotation of the prop stand 20 whereas the said means covering the rotor member 36 remains static with respect to the rotation of the rotor member and does not rotate with the rotation of the prop stand 20. The rotation of prop stand defines the operative and the withdrawn position. Initially the prop stand is in the withdrawn position at which it is substantially parallel to the ground. Further rotation of prop stand beyond the withdrawn position is restricted due to the tapered portion 21a of the mounting bracket 21. The prop stand thus cannot rotate beyond a certain angle when pulled back from the operative position. This angle formed between the operative and withdrawn position of the prop stand is called the "operating angle" as shown in Figure 8. In the withdrawn position, the fixed electrodes 38 are not in contact with the movable electrode 33 and hence the position detection and alerting mechanism 30 is not actuated and no audible signals, or display signals, or audible and display signals are actuated.

[00036] For parking the vehicle temporarily, the prop stand 20 is rotated to the operative position from the withdrawn position. Figure 9 shows a sectional rear view to illustrate the functioning of the position detection and alerting mechanism when the prop stand is in operative position. If the rider forgets to pull back the prop stand 20 in operative position while reusing the vehicle M and the vehicle ignition is on, the movable electrode 33 disposed on the rotor member 31 and the fixed electrodes 38 attached to the body cover 36 come in contact with each other on account of the rotation of the rotor member 31. The rotation of the rotor member took place when the prop stand was previously rotated to the operative position. Hence the position detection and alerting mechanism 30 is actuated. The mechanism 30 detects the position of the prop stand 20 as operative and the result is carried through the electric cables 43 to the audible means, or display means, or audible and display means which alert the rider of the vehicle through the audible signals, or display signals or both respectively.

[00037] Usually the prop stand 20 is spring loaded through the stand spring 23. So when in withdrawn position, it moves quickly to the operative position due to which the movable electrode 33 may touch the fixed electrodes 38 rapidly and may create a shock impact leading to the failure of the mechanism 30. Hence it is necessary to preload the movable electrode 33 to a workable extent at a certain angle. This preloading is achieved by deflection of the movable holder 32 at a certain angle. The movable holder 32 is flexible in the rotation direction due to which it deflects to absorb the impact of a strong shock and gives the preload. It also reduces the wear and tear and damaging of the contacting surfaces of the respective electrodes. Additionally, preload helps to actuate the mechanism 30 before the prop stand is stretched in its entirety along the operating angle. So the position detection and alerting mechanism 30 is actuated when the prop stand traverses an angle Z which is equivalent to operating angle less the preload angle.

[00038] The prop stand 20 is generally restricted in its rotation on the two sides by either the mounting bracket 21 or a stopper provided therein or both. The frequent opening and closing of the prop stand may result in wearing out of either the prop stand contacting surface in contact with the mounting bracket or the prop stand contacting surface in contact with the stopper or both due to which the operating angle of the prop stand may increase. Likewise, the contacting surfaces of the respective movable and fixed electrodes of the mechanism may also wear out. Additionally, the operating angle may reduce if the prop stand contacting surface(s) is covered by a layer of undesirable deposits including grease, mud, wet soil or the like. The position detection and alerting mechanism in the present subject matter would be activated even in all these conditions thereby facilitating longer reliability and durability of the mechanism. The flexible movable holder 32 will make up for the addition or reduction in the operating angle. Further, the positioning of the cavity 37 in the body cover 36 coupled with the dust seal 42 ensure that the electrodes remain at the uppermost position with respect to the ground during their functioning and are thus protected by undesirable foreign matter like water, mud, wet soil and the like.
[00039] Further, according to an aspect of the present subject matter, the movable holder 32 is made of a suitable material including an elastic material and the means for covering the rotor member 36 may be made of plastic resin. [00040] The present mechanism is functional only when the vehicle ignition is switched on and the prop stand is in the operative position. The mechanism draws power from the battery. The electric cables flowing out of the mechanism may be connected to an electric unit such as a TCI (Transistor Controlled Ignition) unit from which the output will be received. The output may be in the form of the audible signal, or a display signal, or audible and display signal. The display signal may be projected through the display means mounted on an instrumental cluster of the vehicle placed forwardly of the vehicle rider. According to an embodiment of the present subject matter, the vehicle rider will be alerted first by the audible signal for a few seconds and after the audible signal goes out, the display means on the instrument cluster will project the output till the prop stand is withdrawn by the rider.

[00041] The present subject matter and its equivalent thereof offer many advantages, including those which have been described henceforth. The position detection and alerting mechanism provides a cost effective and durable mechanism to alert the vehicle rider. It works well with a two wheeled vehicle with a lower ground clearance during rainy season, on flooded roads, or during splash of foreign matter like mud, water, wet soil and the like on the prop stand. The body cover and the dust seal prevent entry of the foreign matter into the mechanism and therefore increase its durability and reliability. [00042] The present subject matter is thus described. It is to be noted that the position detection and alerting mechanism can also be a position detection and alerting device with described components. The description is not intended to be exhaustive nor is it intended to limit the invention to the precise form disclosed. It will be apparent to those skilled in the art that the disclosed embodiments may be modified in light of the above description. The embodiments described are chosen to provide an illustration of principles of the invention and its practical application to enable thereby one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore the forgoing description is to be considered exemplary, rather than limiting, and the true scope of the invention is that described in the appended claims.

I/We claim:

1. A position detection and alerting mechanism comprising: a rotatable rotor member; a means for covering the rotor member, the said means being static with respect to the rotation of the rotor member; atleast one movable electrode mounted on a flexible movable holder, the movable holder disposed in a slot of the rotor member; atleast one fixed electrode held in a cavity of the said means through an insulating and sealing member; a dust seal provided at a hollow end of the said means;

wherein the said mechanism is mechanically connected to a prop stand of a two wheeled vehicle and electrically connected to an audible means, or a display means, or an audible and a display means; and

wherein the prop stand is pivotable about a mounting bracket through a pivot bolt and defines an operative and a withdrawn position; and

wherein when the movable electrode comes in contact with the fixed electrode on rotation of the prop stand to the operative position and when the vehicle ignition is on, the said mechanism alerts a rider of the two wheeled vehicle, and

wherein further the shock load on excess rotation of the prop stand is absorbed by the flexible movable holder.

2. The position detection and alerting mechanism as claimed in claim 1,

wherein the said movable electrode and the said fixed electrode are substantially planar and angularly disposed to each other.

3. The position detection and alerting mechanism as claimed in claim 1 and 2, wherein a portion of the said mechanism is supported through an extension of the said pivot bolt and another portion of the said mechanism is supported by a holding bracket in contact with the said mounting bracket.

4. The position detection and alerting mechanism as claimed in claim 3, wherein the said holding bracket comprises a flat end and an arc shaped end, the latter largely semi-circular in shape and affixed to a portion of the said means, and the former joined to the said mounting bracket through a known joining mechanism.

5. The position detection and alerting mechanism as claimed in claim 1, wherein the said dust seal is circumferentially in contact with a surface of the said prop stand.

6. The position detection and alerting mechanism as claimed in claim 1, wherein the said movable holder of the said rotor member is preloaded, is made of a suitable material including an elastic material and the means for covering the rotor member made of plastic resin.

7. The position detection and alerting mechanism as claimed in any of the preceding claims wherein the said prop stand is located forwardly to the said mechanism.

8. A prop stand assembly configured to support a two wheeled vehicle during parking comprising: a prop stand, a mounting bracket connected to a frame of the vehicle, a pivot bolt configured to pivotally attach the prop stand to the mounting bracket, wherein the position detection and alerting mechanism according to any of the preceding claims is mechanically connected to the said prop stand assembly.

9. A position detection and alerting device mechanically connected to a prop stand of a two wheeled vehicle, including a motorcycle, the said device comprising: a rotatable rotor member with a movable electrode disposed on a movable holder on the rotor member, a static body cover with spaced body electrodes, a dust seal at a hollow end of the said body cover wherein when the prop stand is in a withdrawn position, the movable electrode of the rotor member is not in contact with body electrodes of the body cover, the device being non-functional, and wherein when the prop stand is in an operative position and the vehicle ignition is on, the movable electrode of the rotor member makes a contact with the body electrodes of the body cover at an angle equivalent to an operating angle less a preload angle, thereby actuating the device, the excess rotation being absorbed by the flexible movable holder and the output signal of this device alerting the rider in the form of an audible signal or by a display means or both.

10. A position detection and alerting mechanism substantially as herein described and illustrated by the accompanying drawings.