GB2456315A

GB2456315A - Bicycle seat adjustment assembly

Info

Publication number: GB2456315A
Application number: GB0800380A
Authority: GB
Inventors: Daniel Michael Mcganty
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-10
Filing date: 2008-01-10
Publication date: 2009-07-15
Also published as: GB0800380D0

Abstract

The assembly comprises a seat stem with an arc-shaped track 1, a carriage to move along the track 2, a bracket 3 for the seat on top of the carriage, and a sprung pin 4 which when in place holds the carriage in a selected position on the track. The track 1 has end stops 9 to prevent the carriage from leaving the track. The pin 4 is operated by a cable 5 from the bicycle handlebar for adjustment during riding.

Description

DescrlDtion Bicycle Seat Stem This invention relates to a device for enabling a cyclist to move the seat to the optimal position for uphill, level and downhill riding.

When riding a bicycle on level terrain, approximately fifty-five to sixty percent of the total weight of the bike and cyclist is on the back wheel. On uphill terrain, however, assuming a cyclist remains seated on a traditional, fixed seat, the centre of gravity shifts backwards, increasing the percentage of weight on the back wheel. On a twenty degree incline, for example, approximately eighty-five percent of total weight will be on the back wheel.

There are two detrimental aspects to this significant shift in the centre of gravity.

Firstly, it can become very difficult to steer the bicycle, particularly on rough terrain, with so little weight on the front wheel. Secondly, with the rider's weight no longer over the pedal sprocket, it is not possible for the rider to use his or her body weight to efficiently power the bicycle, maldng it more difficult to progress up the hill.

When riding downhill, a similar but opposite effect occurs, with weight shifting significantly to the front wheel. While power is rarely a problem when going downhill, this forward centre of gravity places the rider in a potentially dangerous position when braking, as the risk of going over the handlebars increases dramatically.

This risk limits the ability of the rider to use the brakes on the bicycle to their full potential.

This invention solves these problems by enabling the rider to move the seat forwards or backwards, to maintain a balance of weight between the front and back wheels, on both uphill, level and downhill riding. At the same time, the invention enables the rider to remain directly over the pedal sprocket, enabling the rider to efficiently use his or her body weight in powering the bicycle.

With this invention, the seat is moved forwards or backwards on an arc-shaped track.

The arc-shaped track forms the top of a seat stem which fits into the standard seat stem opening on the frame of the bicycle.

The seat itself is secured to a carriage which is grooved along its inside to move along the length of the track. The carriage can be fixed in various places along the track by a sprung pin, which slides into pre-fonned holes in the track. In order to pull back the sprung pin to move the carriage, the rider pushes a lever mounted on the bicycle frame or handlebars, which pulls a cable leading back to the pin.

The track is arc-shaped to keep the rider the same distance from the pedal sprocket in all positions of the carnage, to maximise efficiency in pedalling the bicycle. The track has stops at each end, to prevent the carriage from leaving the track.

The invention will now be described solely by way of example and with reference to the accompanying drawings. All references to orientation in these drawings are with respect to the bicycle in which the invention will be used. For example, a side view' means the perspective from which the invention would be seen in looking at the side orientation of the bicycle.

In these drawings: Figure 1 shows a side view of the invention installed on the bicycle to show its placement and position on the bicycle, Figure 2 shows aside view of the seat stem with the arc-shaped track! and seat carriage 2 with the seat attachment bracket 3, positioning pin 4 and cable 5, Figure 3 shows a cross-section (at A of Figure 2) of the arc-shaped track forming the top of the seat stem, with the groove 10 which enables the seat carriage to remain attached to the track, Figure 4 shows a side view of the seat carriage, with the seat attachment bracket 3, positioning pin 4 and cable 5, Figure 5 shows a cross-section of the seat carriage (at B of Figure 2).

In figure 1, other than the invention as shown in the remaining drawings and as described above and below, the other parts of the bicycle do not constitute a part of the invention, and are shown only for context.

Figure 2 shows the arc-shaped track 1 on which the seat carriage moves, which forms the top of the tubular seat stem 6 which fits into the bicycle frame, as well as the seat carriage 2 which moves along the track and the stops 9 which prevent the carriage from leaving the ends of the track.

Figure 4 shows the pin 4 which, when in place, stops the carriage from moving on the track. Figure 4 also shows the spring 7 which pushes this pin into the holes in the track, as well as the cable 5 which pulls this pin back when the lever is pushed at the other end of the cable.

Figure 5 shows the ridge 8 in the seat carriage which holds this carriage on the track (with this ridge travelling in the groove 10 of the track as shown in Figure 3).

Claims

Claims I. A bicycle seat stem providing means for attaching a seat to a bicycle, an arc-shaped track forming the top of the stem, a carriage which can be moved forward and backward on the arc-shaped track, an attachment bracket for the seat on top of the carriage and a sprung pin to fix the carriage in place at various places along the arc-shaped track.
2. A bicycle seat stem according to claim 1, in which the arc-shaped track forms the top of the stem which fits into the frame of the bicycle.
3. A bicycle carriage to claim 1, in which the sprung pin is attached to a cable leading to a lever mounted on the handlebars or frame of the bicycle.
4. A bicycle stem according to claim 1, in which stops at the end of the arc-shaped track prevent the carriage from leaving the ends of the track.