AU2004100489A4 - Bicycle Front Wheel Drive Assembly and Adjustable Rear Dropouts - Google Patents

Description

Bicycle Front Wheel Drive Assembly and Adjustable Rear Dropouts Development a of recumbent bike that enjoys the same economies of scale as others on the market is impossible because about 200 regular style bikes are sold for each one recumbent that is built. A solution would be to devise a means to adapt an existing bike frame to a recumbent, thereby taking advantage of huge production volumes, reducing manufacturing, assembly and distribution cost to a comparative level and delivering commensurate value to customers.

This innovation provides a reversible conversion kit that can be applied to a common bicycle frame having a telescopic front fork suspension to change it to a recumbent style, without any permanent modification to the original bike so that the conversion can be reversed if desired.

Prior art in reversibly converting conventional bicycles to recumbent bicycles produces a rear wheel drive recumbent bicycle (DE19722973 1998-12-03 BRAUNSTEIN STEFAN with small front and rear wheels or a front wheel drive but rear wheel steer bicycle (DE3700388 1988-07-21 SCHELOWSKY MICHAEL A number of bicycle enthusiasts have attempted to realise such a configuration but in each case have found that it is unridable.

There is also significant prior art in another form of front wheel drive made popular by the Dutch Flevo company which utilises a lower head stem angle together with a devise that applies a force that will automatically centre the steering front wheel and a pair of handlebars that are connected to main part of the cycle, not to the steering part. Essentially the rider steers soley with the legs. It may take several days to learn how to ride bicycles of this configuration, which is a major drawback.

It is difficult to convert a regular full size bicycle to a rear wheel drive recumbent because the full size turning front wheel of the conventional bicycle severely limits the viable positioning of the pedals. Additional chain length is needed and often other chain guidance measures also. A front wheel drive configuration for a bicycle (United States Patent D277,744 Traylor February 26, 1985) overcomes these constraints. Experience of riding bicycles that combine front wheel drive and front wheel steer has taught and the theory of bicycle steering geometry has shown that head stem angles several degrees lower to the horizontal than conventional bicycles can provide improved vehicle handling characteristics.

This invention builds on the prior art defined by Traylor (United States Patent D277,744 Traylor February 26, 1985).

The rear wheel of a standard bike (herein called the 'drive wheel') cannot be fitted between the front telescopic suspension forks of a standard bike because the distance between the dropouts designed to carry the front wheel (herein 'idle wheel') and hence is around 25 mm too narrow. The fork legs cannot be splayed apart because telescopic suspension tubes operate in parallel. Also, the fork legs clash with the gear cluster of the drive wheel.

In this invention, a drive assembly is created to carry the drive wheel forward of the fork drop outs, provide the necessary width to carry the drive wheel axle and create the necessary space for the drive wheel gear cluster. The drive axle is kept the correct distance from the brake pads, so that the original braking system can be used unaltered.

The rear dropouts of a conventional bike are around 25 mm too wide for the idle wheel.

In this invention a pair of adjustable rear dropouts is created that fix securely to the original rear dropouts so that the inner faces of the adjustable dropouts are positioned the correct distance apart to support the idle wheel, commonly 100 mm apart and a series of matching open ended slots to receive the axle of the idle wheel is positioned so that the rim of the idle wheel remain adjacent to the rear brake pads. The open ended slots are located so that the idle wheel can be mounted progressively higher in the frame, thereby decreasing the angle of the steering axis as measured to the horozontal.

The invention may be better understood with reference to the illustrations of embodiments of the invention which: Figure 1 is a Front Elevation of the Bicycle Front Wheel Drive Assembly Figure 2 is a Left Side Elevation of the Bicycle Front Wheel Drive Assembly Figure 3 is a Rear Elevation of the Bicycle Front Wheel Drive Assembly Figure 4 is a Right Side Elevation of the Bicycle Front Wheel Drive Assembly Figure 5 is a Left Side Elevation of the Adjustable Rear Dropouts 13 Figure 6 is a Side Elevation of the conversion kit as applied to a common bicycle frame, with the common bicycle frame, recumbent seat and wheels shown in dashed line for illustrative purposes only.

The bicycle front wheel drive assembly has: a pair of drop outs 11 that are bolted through pivoting joints 12 to the conventional bicycle at the front fork drop outs rotated half a turn; a pair of arms 10 connecting the dropouts to a crank bearing shell 9; a mounting bracket 8 connected to the bearing shell 9; an adjustable length bracing tube 5 to which is attached with a pivoting connection 7 at its forward end 6 that attaches to the mounting bracket 8; a second mounting bracket 2 is attached to a pivoting connection 3 to the rearward end of the adjustble length bracing tube 4; and a gooseneck extention tube 1 to which the second mounting bracket 2 is connected.

The Adjustable Rear Dropouts 13 have an attachment 14 for securely connecting to the rear dropouts of the original bicycle and a series of slots 15 for receiving the idle wheel and incrementally lifting the wheel in the frame. The Adjustable Rear Dropouts are designed to hold the idle wheel in various positions all of which place the wheel rim adjacent to the brake pad so that the original braking system for the rear wheel can be used unaltered.

The various elements of the invention may be made of various materials and may be strenthened by flanges, webbing or other like structural means as required by those materials.

The following concerns the bicycle front wheel drive assembly.

The pivoting joints 12 may be made made from ball bearings or as a bushing or other means.

The inner faces of the drop outs 11 will in most situations be wider than the outside faces of the front fork dropouts of the original bicycle. This gap can be bridged by the bearing structure of the pivoting joint 12 or by spacing washers. Alternatively, the dropouts can be bent inwards in the portion behind the drive wheel axle to bridge this gap.

The drop outs 11 are shaped in order to accommodate the lower extremity of the front fork legs and to position the drive wheel to give the appropriate rake, which is the distance from the turning axis of the steering assembley to the front wheel axis (in this case the drive wheel) measured at their closest point.

The drop outs 11 are may be shaped to accommodate fittings associated with the bicycle gear mechanism or to make provision for a disk brake.

The pair of arms 10 may be constructed from tapered tubing or tubing that is parallel and may have reinforcing webs or other structural enhancements as necessary. Specific fixtures for mounting braking components can be utilised as an enhansement.

The mounting brackets 8 and 2 may be of various commonly used designs.

The pivoting connections 7 and 3 may be of various commonly used designs employing bearings, bushings or other means.

The adjustable length bracing tube 5 could be of various diameters and wall thicknesses appropriate to the materials being employed and could be of any cross sectional shape.

Claims (4)

1. A bicycle front wheel drive assembly having a pair of dropouts that pivotally con- nect to the front fork dropouts of a conventional bicycle and which hold a drive wheel in the correct position, which are connected via a pair of arms to a crank bearing shell which is pivotally connected to a bracing tube which is pivotally con- nected to a gooseneck extention.

2. A bicycle front wheel drive assembly according to any claims 1 and 2 wherein the bracing tube is adjustable in its length thereby positioning the crank bearing shell to suit riders of varying leg lengths.

3. A bicycle front wheel drive assembly according to any one of the claims 1 to 3 wherein the gooseneck extention is adjustable in the height at which it connects to the fork neck tube.

4. A bicycle front wheel drive assembly according to any one of the claims 1 to 4 which will reversibly convert a bicycle to a recumbent configuration utilising all of the components of the original bicycle save for the seat. Adjustable Rear Dropouts that securely fix to the rear dropouts of the original bi- cycle and allow the wheel to be placed lower in the frame while retaining the cor- rect distance to the rear brake pad.