A bicycle seat

Abstract: A bicycle seat is claimed which has no horn and permits an even weight distribution on the ischia of the cyclist as well as permitting unobstructed pedalling and correct positioning in relation to the handlebars and pedals to maximise efficiency and comfort of pedalling. The seat has a wide rear portion (12) moulded to support the buttocks at both the rear sides and a front portion which has a leading edge (16) extending at right angles to the frame. The leading edge lies in the physiological creaseline (18) of the cyclist between the thighs (20) and buttocks (22). The seat is attached to the seat post close to its leading edge.

Description: FIELD OF INVENTION This invention relates to a seat for a bicycle. BACKGROUND OF THE INVENTION Saddle discomfort is a major problem that millions of cyclists experience every day. And saddle-induced pain is the major reason why millions of non-cyclists who would like to cycle, don't. For decades, bicycle manufacturers have been aware of these shortcomings. Dozens of different saddle designs have been experimented with, and today there are literally hundreds of different bicycle designs to choose from ... all kinds of shapes, sizes and materials. Not one is the solution to saddle discomfort and pain. Genital numbness occurs in both men and women, but is more common in men. It is usually the result of saddle pressure on the two pudendal nerves in the crotch. This may be caused by a variety of conditions. Attempts to alleviate the condition include avoiding hill climbing in a seated position, moving about on the saddle from time to time, standing to pedal occasionally, or assuming a more upright position. It is usually best that the saddle be level rather than tipped up or down, but slightly lowering the nose of the saddle may help. Some riders tilt up the nose of the saddle to force a more upright position. The saddle may also be too high. Leg extension should be about 95% with the pedal at 6 o'clock, and the hips should not rock when the pedals are moved backward with the heels. These are however cyclists' responses or adaptations to the situation which are simply treatments for the symptoms and not the cause. A saddle that is too hard may cause problems, especially if it is made out of hard plastic that will not adjust to one's body over time. Hard leather saddles adjust to a cyclist's body if treated correctly. A soft saddle should be avoided since it can cause more problems than it solves. One that gives slightly is all that is needed. Too long a reach on the handlebar stem extension can also cause numbness, but the stem must be replaced to fix this. The saddle should not be moved forward to alleviate the problem. Moving the saddle fore and aft should only be done to put the knees over the pedal spindles. Not particular to women, but common to them, is having a saddle too narrow to support the ischia, or "sit-bones". Having the seat too far from the handlebars is especially common for women riding a bike sized for a man - as most of them still are. The saddle should not be fore and aft to compensate for the stem reach. Saddle adjustment should only be done to correctly position the knees over the pedal spindles. If the saddle is too far back, a shorter stem extension is required. Ischial Bursitis is another fairly common problem. This is an inflammation of the fluid filled sacs that are a natural cushion over the ischia. Increased conditioning and adjustment of the saddle may relieve the condition, but invariably the problem lies with the type of saddle being ridden. Recently another potentially more serious problem has begun to emerge ... that of physical damage over time to the genitals leading to sexual dysfunction. A urologist at the Boston University Medical Centre in USA estimates that he sees six cases of bicycle-related impotence each week. The problem is anatomy vs. the bicycle saddle. A person's body is designed so that when one sits down, one's weight is distributed on two sit bones, the ischia. These are protected by muscle and fat, and they contain no arteries or anything else of importance that could be crushed by a person's body weight. This area is custom-made for sitting on flat surfaces such as chairs. However a bicycle saddle is much narrower and fits between the sit bones, with a smaller protrusion tucked up in the crotch. It is in this area that the body accommodates nerves and arteries leading to the penis. These arteries are responsible for the blood flow that causes erections. If they are crushed, blood cannot get to the penis. Once crushed, arteries don't always bounce back. Any pain or numbness felt after a long ride is not an innocent inconvenience - it cold mean trouble. For with no blood reaching the penis, there's no erection. When one sits on a chair, no blood is obstructed through these arteries. When a person sits on a narrow bicycle saddle, there is a 66 percent reduction in the blood flow. Overall, there are about 100,000 men in the USA who have problems with impotence because of bicycle-related damage. Women are not immune either. When members of a Boston-area cycling club were surveyed, not only impotence found in men but also complaints about diminished sexual sensation and drive from women. Women's physiology in this particular area is similar to men's, and it is suspected that similar injuries occur in women. Problems with the traditional saddle therefore are two-fold. Firstly the saddle horn is a major obstruction and causes discomfort across a wide range of degrees of pain. Secondly, the lack of support for the buttocks, and especially the ischia bones, forces much of the body weight to be taken up along the crotch-sphincter-coccyx line, with its attendant discomfort, pain and potentiality for impotency. However it has been found that saddle discomfort cannot be examined purely from the point of shape, hardness and texture of the saddle. Whilst the saddle design is very important, the key to a particular cyclist establishing a comfortable and efficient riding position is the establishment of the correct triangulation relationship between the handlebars and the crank axle, the crank axle and the seat and the seat and the handlebars, for the size and shape of the cyclist in question. Of these three points, the crank axle at the bottom of the inverted triangle is fixed, and therefore it is only the positions of the handlebars and seat which can be manipulated in the design/manufacturing stage, or tuned in the field by way of an adjustable handlebar stem and an adjustable seat post. Handlebar stem adjustment is critically dependent on the saddle being in the correct position before the stem is installed. Thus the position of the seat is in effect the determining aspect of correct triangulation. And this depends most of all on selecting a frame with the appropriate seat tube angle, with alteration of seat post angle and seat post length providing adjustment options of lesser importance than starting with the correct seat post angle in the first instance. The seat tube angle is measured between the top tube (the crossbar) and the seat tube (which takes the seat post) where they join under the seat. In terms of frame geometry, this angle has varied over the years but generally the seat tube angle can be anywhere from 68 to 75 degrees (90 degrees being vertical). Selection of the correct seat tube angle is key to acquiring the bicycle most suitable for the purpose the rider has in mind to use it for, e.g. racing, cruising, mountain trailing, and the like. For every one degree of change in the angle of the seat post, on a 30cm seat tube the alteration in the position of the top of the seat tube is only 5.3mm. Nevertheless, this relatively small change in triangulation makes a big difference to the overall handling of a bicycle. This is the major reason why, having selected a frame with the most appropriate seat tube angle for their purpose, if professional cyclists then need to make saddle adjustments these are only of one or two millimetres at a time. Further, being situated at the top of the seat post, how the seat (or saddle) is positioned in relation to the seat tube is of critical importance in regard to the physical comfort and pedalling efficiency/effectiveness of the cyclist. In this application, the applicant proposes that the physiological curve (or crease) of the cyclist at the line where the forward portion of the buttock and the posterior portion of the thigh critically needs to lie on the line of the upward extension of the front edge of the seat tube leading into the underside of the seat. It has been discovered that this principle must be followed within the constraints of a few millimetres if the cyclist is to be able to complete the correct triangulation of seat-handlebars-crank axle. If this creaseline is too far forward of the seat tube extension line, the cyclist loses pedal leverage which decreases pedalling power and causes leg strain on hills, and the handling of the bicycle is adversely affected. If it is too far back, it will lead to back strain. It is at this point where prior art seating arrangements have failed. For some time it has been recognised that the horn should be dispensed with and that the buttocks require better support. In some cases, the prior art patents have also recognised the fact that the position and shape of the leading edge of the seat should correspond with the physiological curve (or crease) between the posterior portion of the thigh and the anterior portion of the buttock of the cyclist. This allows the cyclist's genitalia to lie forward and clear of the seat and reducing if not removing completely the risk of damage and impotence. However, in none of the prior art examined have the applicants taken into account of the interaction of the seat shape, the positioning of the leading edge of the seat in relation to the physiological creaseline described above as well as the relative positions of the leading edge of the seat and the seat-post. It is this positioning which is also critical and in the prior art examined it was found that the seat post did not fit immediately under the physiological creaseline of the cyclist when positioned correctly on the seat. As a result the cyclist was either positioned too far forward in some cases, or in most cases, too far back. This not only leads to inefficient pedalling, but also discomfort and possible injury. In all prior art patents examined of which the most relevant were found to be Scarcella (US D326782), White (US D348785), Cesar (US D370132), Marchello (US 3874730 and US 4176880), Barker (US 4387925), Golden (US 4572575 - expired), Gordon (US 4613187 - expired), Terranova (US 4773705 - expired), Rollman (US 4850643 - expired), Hobson (US 4877286 - expired), Sunshine (US 4950004), Hodges (US 5123698 - expired), Denisar (US 5387025) and Wilkinson (GB 2319231), none takes into account the relative positioning of the leading edge of the seat to the seat post in relation to the physiological creaseline of a cyclist in the zone between the posterior of the thigh and the anterior of the buttocks. It is therefore an object of this invention to provide a bicycle seat in which the seat post fits immediately under the creaseline of the rider when the rider is correctly positioned on the seat causing the rider to be ideally positioned on the bicycle in terms of pedalling power, pedalling efficiency and comfort. It is a further object of the invention to provide a bicycle seat which places the rider in the ideal position on a bicycle frame as determined by scientific principles as enumerated earlier, and which provides the most in terms of comfort and protection because it leaves the legs and genitalia area forward of, and therefore completely clear of, the leading edge of the seat and takes the full sitting weight of the body on the buttocks which is their essential purpose in the first place. This completely eliminates the possibility of pressure, pain and damage to the crotch area, removes concerns about possible saddle-caused impotency, and enables the legs to move freely in the desired cycling action without friction between the legs in and around the inner thigh and crotch area. Closest prior art document US-A-4773705 shows a combination of a bicycle seat and a seat post the seat being attached to the seat post by mounting means, the seat including a unitary surface having a rear portion moulded to support the rear and sides of the buttocks at least in part and a wide section having raised formations at the periphery thereof; and a front portion having a substantially straight leading edge extending horizontally and substantially transversely to the frame of the bicycle. US-A-4773705 shows that the leading edge of the seat projects well forward of the seat post. THE INVENTION The present invention defined by claim 1 and by claim 6 differs from the closest prior art known from US-A-4773705 in that the seat is attached to the seat post at a point at the leading edge abutting the zone between the posterior of the thigh and the anterior of the buttocks of a seated cyclist. The surface may further include in the rear wide portion thereof, a pair of spaced apart depressions for receiving a cyclist's buttocks in the region of the ischia bones. The seat of the invention as described is moulded to support the cyclist's buttock with the peripheral rim ,serving this purpose. This also assists in positioning the body naturally on the seat. Furthermore, the presence of the depressions relieves the pressure placed on the cyclist's ischia. The front of the seat has no horn, but instead the leading edge of the seat runs at right angles to the bicycle frame and aligns with the physiological creaseline falling in the zone between the thighs and buttocks of the cyclist. This positioning allows the genitalia of the cyclist to lie forward and clear of the seat itself with the result that little or no pressure is placed on the pudendal nerves. This reduces the likelihood of discomforts such as numbness and also the potential for long term damage to the genitalia in the form of saddle induced impotence. The positioning of the seat post at the leading edge of the seat permits the cyclist to adopt a proper position on the bicycle in relation to the seat-handlebars-pedals triangle and in so doing permits seating in a manner which is comfortable, allows a free and unencumbered pedalling motion without friction between the legs in and around the inner thigh and crotch area. EMBODIMENT OF THE INVENTION An embodiment of the invention is described below with reference to the accompanying drawings, in which:- Figure 1 is an isometric view of a seat according to the invention; Figure 2 is a top view of the seat; Figure 3 is a front view; Figure 4 is a rear view; Figure 5 is a side view; Figure 6 is a side view showing seat post; and Figure 7 is a sectional side view with seated rider. In the drawings a bicycle seat 10 comprises a supporting surface with a rear portion 12 which is wide and moulded to support the rear and sides of the buttocks (see Figure 7). Peripheral rim 14 performs the support function. The front portion of the seat has no horn but instead has a leading edge 16 which lies at right angles to the bicycle frame. The seat is dimensioned such that when a rider is seated, the leading edge 16 is positioned in the zone 18 (Figure 7) between the posterior of the thigh 20 and the anterior of the buttock 22. The leading edge may be slightly arcuate and rounded for comfort. This shape allows the cyclist to be comfortably seated with his weight distributed evenly on the ischia instead of between them on the crotch-sphincter-coccyx line. Furthermore, the buttocks are well supported from the sides and from the rear, while the position of the leading edge of the seat which is tucked into the physiological creaseline 18 of the cyclist between the thighs and buttocks permits the legs to pedal freely unobstructed by a horn. Depressions may be provided at 24 to further accommodate the ischia. In order to position the cyclist on the seat 10 correctly in relation to the handlebars and pedals, the applicant proposes attachment of the seat 10 to the seat post 30 on the frame 32 at a point very close to the leading edge of the seat. It has been found that by affixing the seat here, only a small adjustment may be required and accordingly the point of attachment should be between the leading edge 16 and a point 25 millimetres rearwardly of the edge (see Figure 6). It is this positioning together of the leading edge 16 of the seat 10 in line with the seat post 30 and the position of the leading edge 16 abutting the physiological creaseline 18 of the cyclist which allows the cyclist to be correctly positioned for comfortable and efficient pedalling.

Claims: A combination of a bicycle seat (10) and a seat post (30) the seat (10) being attached to the seat post (30) by mounting means, the seat including a unitary surface having a rear portion moulded to support the rear and sides of the buttocks (22) at least in part and a wide section (14) having raised formations at the periphery thereof; and a front portion having a substantially straight leading edge (16) extending horizontally and substantially transversely to the frame (32) of the bicycle, characterised in that the seat (10) is attached to the seat post (30) at a point at the leading edge (16) abutting the zone between the posterior of the thigh and the anterior of the buttocks of a seated cyclist. A combination according to Claim 1 characterised in that the unitary surface includes in the rear wide portion thereof, a pair of spaced apart depressions (24) for receiving a cyclist's buttocks (22) in the region of the ischia bones. A combination as defined in any one of the preceding Claims characterised in that the raised formations at the periphery of the seat take the form of a peripheral rim (14). A combination as defined in any one of the preceding Claims characterised in that the raised formations reduce in height towards the front of the seat (10). A combination as defined in any one of the preceding Claims characterised in that the leading edge (16) comprises a pair of arcuately curved surfaces, one disposed either side of a central axis of the seat (10). A bicycle fitted with the combination as defined in any one of the preceding Claims.

Inventors: DALTON ANTHONY BERESFORD CLAUD, LAWSON DONALD GARTH, DALTON, ANTHONY BERESFORD CLAUDE, LAWSON, DONALD GARTH
Applicants: SUPASEAT HOLDINGS LTD, SUPASEAT HOLDINGS LIMITED
Application year: 1999
Main classification: B62J1
IPC codes: B62J1