DE20000170U1 - Bicycle with lowered seat height - Google Patents

Description

DESCRIPTION

The invention relates to a bicycle with a lowered seat height, with a conventional steering geometry, with a usual inclination of the steering axis and with a frame on which a steering head tube, at least one steerable front wheel mounted in a fork or a bracket, at least one rear wheel mounted in a rear frame, a saddle adjustable with at least one degree of freedom, a bottom bracket housing moved further forward at a standard height above the ground for mounting a pedal crank drive and a handlebar with two grips for steering the front wheel are arranged. The bicycle with a lowered seat height is equally suitable and applicable for women, men and children, and of course different sizes can be produced.

This type of bicycle is essentially the same as a conventional bicycle design, which is also known with a smaller front wheel, especially as a transport bicycle. The classic bicycle concept requires a favorable sitting position (basic position). In the basic position, a cyclist should be able to ride for hours without feeling tension in the muscles, tendons and joints. The arms are slightly bent at an angle of 150°, the upper body is at an angle of 45° to 50° to the horizontal and the center of the knee joint is vertically above the pedal axis during the pressure phase (see, for example, the book by Michael Gressman "Bicycle Physics and Biomechanics", 5th edition, 1993, p. 176, Moby Dick, Kiel). However, this sitting position requires different saddle shapes for men and women.

Another problem with the classic bicycle is the unnatural posture that the rider adopts, which is not found in any other situation in life. The rider sits largely folded in on the saddle and pedals downwards. When accelerating strongly, the rider lifts himself out of the saddle and stands on the pedals. He holds on to the handlebars with his arms, partly to be able to maintain his balance, but also to divert some of the forces that lift him out of the saddle into the handlebars. The arms are therefore involved in the propulsion process asymmetrically and are not used exclusively for steering the bicycle.

A bicycle of the type described above is known from the magazine "RadMarkt", No. 9, 1998, p. 28, Bielefelder Verlagsanstalt KG, Bielefeld, Germany. The seat height is considerably lower than that of a normal city bike, which ensures safe starting and stopping. The feet can be placed well, and a light push-off is enough to start off. To ensure the correct distance to the pedals when riding, the bottom bracket has been moved further forward. This and the use of a suspended seat post contribute to a relatively comfortable sitting position. Overall, the U-shaped frame is slightly extended and, as an additional effect, offers an optimally low and very wide

Step-through. However, this frame geometry does not offer an optimal seating position. In addition, a steerable 2.6-inch front wheel requires a steering head angle of 65 degrees. This and a relatively long wheelbase will have a negative impact on handling, especially in city traffic.

A frame for a bicycle scooter is already known from DE-PS 907 747, in which the leg position in relation to the pedal crank is designed to be flatter than on a normal bicycle, using small wheels, by placing the bottom bracket further forward than usual. The steering head is about twice as long as on a normal bicycle. The saddle has a low edge at the back to prevent it from slipping backwards. It can be pushed onto the seat tube from the front and back and, unlike a conventional bicycle, is arranged in a forward-facing, upward-facing slant. This frame structure does not offer an optimal seating position and is not cheap to manufacture, as it uses special components that differ from those used in conventional bicycle construction and cannot be taken from conventional bicycle production.

DE-OS 195 37 095 describes a bicycle with a downwardly curved frame and reduced saddle height with a bottom bracket that is positioned at a standard height above the ground, in relation to the saddle, with an elongated belt drive and different wheel sizes, whereby the diameter of the rear wheel is larger than that of the front wheel. The rear wheel suspension, consisting of a swing arm and tension rod, is attached to the frame via spring elements and joints. A basic luggage rack is integrated into the frame, on which a child seat or rigid panniers can be placed. However, the seat tube is at an angle of around 62° to the horizontal. This leads to the leg being very flat in the pressure phase and to the torso slipping backwards considerably, even due to normal leg pedalling.

A bicycle with 20-inch wheels is known from the magazine "Encycleopedia 97", p. 27, Open Road Ltd., York, Great Britain. The previously known bicycle has a rear frame and a steering unit designed in the usual way. A frame in a buttress design that runs essentially in one plane from the steering head tube to the seat tube forms a low step-through. The bottom bracket is located at about the height of the rear wheel hub and further forward from the seat tube. An extremely long seat post that carries a special moped saddle is slidably mounted in the seat tube. To absorb the driving pressure of the legs, the moped saddle is provided with a backrest at the height of the cyclist's pelvis. The steering unit is provided with a hinge above the steering head bearing so that a stem and handlebars can be folded sideways towards the main frame as required. Due to the very flat steering head angle of around 63 degrees, this bicycle has the disadvantage that the handling is greatly changed compared to the usual inclination of the steering axis. becomes.

The invention specified in claim 1 is based on the problem of creating a versatile bicycle with an optimal ergonomic rider seating position, a normal driving behavior, considerably greater safety, an uncomplicated frame construction and, in addition, a low step-through.

This problem is mainly solved by the following combination features:

a) a rider sitting upright on the saddle can, without any effort, just touch an extremely far-off pedal with a heel of a stretched leg, with his hip joints above the ground at a height of approximately 0.9 to 1.1 of the outside length of the leg stretched out to the pedal and the bottom bracket housing at an angle of 20 to approximately 50 degrees to the vertical from the hip joints to the ground,

(b) in a side view, a geometric centre of the handlebar grips is always located above a crank circle, in particular above the front half of this circle, and substantially above a saddle seat surface.

In addition, this bike should have a unisex saddle that is equally suitable for men and women.

The essence of the invention according to claim 1 is to modify a conventional bicycle frame in such a way that it allows a low seat and a deep step-through, similar to a motor scooter type, through which the user of the bicycle can climb on in a comfortable position and sit on the pedals. This design results in a strictly defined offset of the bottom bracket into the front half of the frame in order to enable effective leg work when transmitting power to both crank arms. It must be taken into account that with this arrangement the saddle's main task is to provide the most comfortable seat possible and it serves very little as a leg guide when pedaling. In order to allow every rider to sit upright on the saddle, the handlebar grips should be positioned sufficiently high above the crank circle.

In addition, the height of the seat is basically determined by the length of the legs. This means that the rider sitting on the saddle can reach the ground with both feet without any effort and stands safely. When riding slowly, the awareness of being able to reach the ground at all times makes them feel much safer.

The combination of the features listed in claim 1 results in a perfect city bike that can be used safely and without danger in today's traffic. This bike with a lowered seat height can also be classified as a single type of bike and placed between the conventional bike and a so-called armchair bike.

The advantageous embodiments of the invention are specified in the dependent claims.

■' Thus, the unisex saddle ("standard saddle") according to ' protection claim 2 offers the advantage of being extremely comfortable to sit on, whereby a saddle surface designed in the usual way is equally suitable for women and men and can be provided with a considerably enlarged seat area, particularly in the contact area with the rider's buttocks.

A preferred embodiment of the bicycle with a lowered seat height, in which a smaller front wheel of about 10 to 24 inches than usual can be used, is specified in claim 3. The further development according to claim 3 makes it possible to offer a steering head tube that is extremely long for attaching a universally usable luggage carrier using the reduced front wheel with direct or indirect steering. By inclining the steering axis in

\5 At an angle of 68 to 73 degrees to the road, a weight of 30 to 50 kilograms can be permitted when transporting goods on the front luggage rack.

The inventive seating position of the driver and the unisex saddle can be used as an alternative to the conventional seating position on the usual saddle on various land, water and air vehicles as well as on stationary sports and exercise equipment.

The invention thus creates a bicycle of this type with a lowered seat height, which can be used in a variety of ways and, of course, can be equipped with more than two wheels.

The embodiments of the invention are also shown in the drawings and are described in more detail below.
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Fig.l the side view of a driver's seating position according to the invention with two outermost limits of body size,

Fig. 2 the graphical representation of a set of optimal positions of the geometric center of the hip joints for all possible body sizes of the driver,

Fig. 3 permissible modifications of the driver’s seating position according to the invention,

Fig. 4 the top view in a schematic representation of a unisex saddle compared to a women's and a men's saddle,

In Fig.l, an image of the rider's sitting position, whose height is schematically divided into two maximum limits, is shown in the scheme of a bicycle with a lowered seat height. The rider, who sits upright on the saddle, can without any effort just touch the extremely far pedal with a heel of one stretched leg and at the same time reach vertically to the ground with the heel of the other stretched leg. This arrangement determines a straight line of geometric centers of the hip joints of the short and tall rider. This line is inclined at an angle ω to the road and can actually be led parallel to a seat tube. The angle ω as well as

A possible direction for adjusting the unisex saddle can be calculated using the following formula:

tg ω = ~zzzzz: ^(A)

V 2(H-R)'

They mean:

Lmin is the outside leg length of the small rider
Lmax is the outside leg length of the tall rider .·. H is the height of the bottom bracket axle above the road surface
R is the length of the crank

From the above conditions of the rider's sitting position, it can be proved that the geometric center of the hip joints of any rider belongs to a branch of a parabola (see Fig. 2), the vertex of which is located under the bottom bracket at a height of (H+R) /2 above the ground. This gives us formula A.

The vertical position of the second leg shown in Fig . 1 is not the only possibility, because in this way only a theoretically average (see formula A) movement path of the unisex saddle for adjustment is to be determined. A crossed-out area in Fig. 2 shows the optimal arrangement of a set of geometric centers of the hip joints for all possible body sizes, whereby the height of the hip joints of one and the same rider can be variable within certain limits, approximately from -10% to +10% of the rider's outer leg length, and the bottom bracket housing is at an angle of 20 to about 50 degrees to the vertical from the hip joints to the ground. This is shown particularly clearly in Fig. 3. This figure also shows the possible dependence of a steering head angle on the rider's seating position.

In order for every cyclist to be able to sit upright, the vertical parallel projection of the movement path of the geometric center 1 of the height-adjustable handles should always be positioned above the crank circle, especially above the front half of this circle. In addition, the handlebars should be located significantly above the seat of the unisex saddle. With these conditions, an orthopedically good sitting position can be determined by the correct relationship between the handlebar position and the rider's sitting position, because the accessibility of the handlebars and the shape of the movement to be performed by the rider when steering are influenced by the rider's sitting position.

Fig. 4 schematically shows the seat shape of the women's saddle (a) and the men's saddle (c) in comparison to the unisex saddle according to the invention (b).

The saddle on a conventional bicycle not only has the task of providing the most comfortable seat possible, it also serves as a leg guide when pedalling. But this cannot be achieved with the

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The so-called "uniform saddle" can be achieved. The sit bones of a woman are further apart than those of a man because of the wider pelvis. Therefore, in contrast to the men's model, the women's saddle requires a wider seat and, due to the way the woman's legs are closed, a slimmer guide nose, which prevents chafing of the thighs.

The requirements placed on the unisex saddle for bicycles with a lowered seat height are different. Due to the inventive seating position of the rider, the unisex saddle has the main task of providing an extremely comfortable seat and serves very little as a leg guide when pedaling. Therefore, a shortened guide nose of the men's saddle can be combined with a considerably larger seat area of the women's saddle in the unisex saddle (b).

In this way, the proposed bicycle type achieves a collision between a universally usable saddle and practical leg pedalling that is not achievable in the conventional bicycle sector.

" The geometric arrangement shown in Figs. 1, 2 and 3 and the use of the unisex saddle b (Fig. 4), which is designed in the usual way with an enlarged seat (support surface), enable the optimal ergonomic driver seating position and practical leg work in all driving situations. The driver holds on to the handlebars with his arms without any effort. In order to prevent the torso from slipping backwards due to the intensive leg work, e.g. when sprinting or when setting off quickly from a standing position, he should use almost all the muscles of both arms and certain torso muscles for static work simultaneously if necessary.

symmetrically. The trunk and arm muscles pull on the handlebars in a jerky manner and increase the pedal force. This type of pedaling technique is similar to the so-called "quick rocking motion" on a normal bicycle, without the rider lifting himself out of the saddle. In this way, the arms are not only used to steer the bicycle with the seat lowered, but are also successfully involved in the propulsion process. Of course, this bicycle should have suitable gear ratios.

The use of the smaller front wheel allows the conventional steering geometry to be retained with a positive axle offset and a steering head angle δ of, for example , 68° to 73° . A significant advantage here is that the lowering of the steering head is minimal with permissible handlebar deflections. The lowering of the steering head depends very much on the steering head angle δ: the flatter the steering axis, the more pronounced the lowering. The small lowering of the steering head makes it possible to allow a large load on the smaller front wheel and at the same time achieve acceptable handling of the bike with a lowered seat height.

Claims (3)

1. Bicycle with a lowered seat height, with a conventional steering geometry, with a usual inclination of the steering axis and with a frame on which a steering head tube, at least one steerable front wheel mounted in a fork or in a bracket, at least one rear wheel mounted in a rear frame, a saddle adjustable with at least one degree of freedom, a bottom bracket housing moved further forward at a standard height above the ground for mounting a pedal crank drive and a handlebar with handles for steering the front wheel are arranged, characterized by an optimal ergonomic driver seating position based on a combination of at least the following features: a) a rider sitting upright on the saddle can, without any effort, just touch an extremely far-off pedal with a kick of a stretched leg, with his hip joints above the ground at a height of about 0.9 to 1.1 of the outer length of the leg stretched out to the pedal and the bottom bracket housing at an angle of 20 to about 50 degrees to the vertical from the hip joints to the ground, ( Fig. 1, 2) b) a geometric centre (1) of the handlebar grips is always located above a crank circle in a side view, in particular above the front half of this circle, and significantly above a saddle seat surface. ( Fig. 1, 3) 2. Bicycle according to claim 1, characterized by a certain shape of the seat of the saddle, which is equally suitable for women and men, whereby the seat of such a unisex saddle can be significantly enlarged, particularly in the contact area with the rider's buttocks, compared to the usual bicycle saddle. ( Fig. 4) 3. Bicycle according to claim 1 or 2, characterized in that by using a reduced steerable front wheel with direct or indirect steering, the steering head tube can be made longer than usual and that the steering axis is inclined in particular at an angle (δ) of 68 to 73 degrees to the roadway.