NL2009882A

NL2009882A - Bottom bracket adaptor for bicycle transmission.

Info

Publication number: NL2009882A
Application number: NL2009882A
Authority: NL
Inventors: Colin Yip
Original assignee: Ebm Solutions Pty Ltd
Priority date: 2012-04-23
Filing date: 2012-11-27
Publication date: 2013-10-28
Also published as: CH706393A2; NL2009882C2; DE102013100312A1; CH706393B1

Description

BOTTOM BRACKET ADAPTOR FOR BICYCLE TRANSMISSION

FELD OF THE INVENTION

The field of the present invention relates to bottom brackets for bicycles, specifically adaptors for bottom bracket to provide more secure attachment of the bottom bracket cups to the bottom bracket.

DESCRIPTION OF THE PRIOR ART

At present, bottom brackets for bicycles have a left hand (non drive side) cup and a right hand side (drive side) cup, each of which thread into an appropriately sized bottom bracket shell. A spindle, or axle, which the bicycle cranks are attached to is housed in the bottom bracket shell through the left and right side cups, each of which house a series of bearings that allow the spindle to rotate.

Most bottom bracket designs require the use of a left-hand threading for the right (drive) side cup (ISO/English standard or BSA - 1.37in x 24TPI). There are a few designs that use right-hand (normal) threading for the right (drive) side cups, such as Italian standard (36mm x 24TPI) or French standard (35mm x 1mm), however the Italian standard is less common and the French standard is almost obsolete.

The English/ISO standard is by far the most prolific bottom bracket threading size and orientation used in the bicycle industry. The use of the left hand threading on the right drive side is the opposite direction to the stroke or motion of the crank so that as the crank rotates it does so in the opposite direction of the threading of the right side cup. However, the use of the left handed thread on the drive side is not actually desirable because the pedalling direction of the bike is right-handed. The turning of the bottom bracket spindle in the right handed manner due to normal use when pedalling forward will exert torque on the bottom bracket cup of the right drive side, causing it to loosen. What prevents this from happening is the use of bearings in the bottom bracket that reduce friction substantially so that little of the torque force from the cranks are transferred to the cups.

As the performance of the bike is improved, a greater force is exerted on the right (drive) side bottom bracket cup and as such it is possible for the right (drive) bottom bracket cup to come off.

When a derailleur or internal transmission crank mechanism is installed on the bottom bracket of the bike, the derailleur is stationary and so the force exerted on the pedals during riding are transferred to the bottom bracket through the derailleur. As this force can be quite high then there is a chance that the right (drive) side of the bottom bracket can loosen and detach from the bottom bracket sleeve, possibly causing harm to come to the user of the bicycle.

Although it may be apparent to address the problem by simply changing the threading direction of the right (drive) side cup from left-hand to right-hand, this is not the accepted industry standard approach. Indeed it is quite the opposite, as most bike manufacturers do not really know if the bike frames they produce will have derailleurs installed on the bottom bracket or not.

In case the manufacturer makes bike frames with right-hand threading at the right (drive) side of the bottom bracket then if the bottom bracket is not of the type that needs a derailleur then their bike frames will not be sellable at all because of the difference of the threading direction from the traditional bottom bracket (English/ISO standard).

OBJECT OF THE INVENTION

It is an object of the present invention to provide a mechanism to change the threading direction of the right side of the bottom bracket sleeve.

Other objects and advantages of the present invention will become apparent from the following description, taking in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

SUMMARY OF THE INVENTION

Throughout this specification the term “drive side” denotes the side that is closets to the chain rings of the bicycle crank. The term “non-drive side” denotes the opposite side, ie the side of the bicycle without the chain rings.

Throughout this specification the term “internal transmission crank mechanism” or “derailleur” denotes an internal crank gear mechanism of the type mountable in close proximity to or immediately adjacent to a bottom bracket of a bicycle. Such mechanisms usually include a planetary gear mechanism.

According to the present invention, although this should not be seen as limiting the invention in any way, there is provided a cylindrical bicycle bottom bracket adaptor, the adaptor including a left hand side sleeve and a right hand side sleeve, both of which are sized to fit within a bottom bracket shell of a bicycle, the left hand side sleeve and the right hand side sleeve adapted to connect to one another, characterised in that the right hand sleeve has an internal right handed thread to threadably engage with an internal transmission crank mechanism.

In use, the left hand sleeve is inserted into the non-drive (left) side of a bottom bracket shell of a bicycle and the right hand sleeve is inserted into the drive (right) side of the bottom bracket shell, the two shells then threaded to one another,

In preference, the left hand sleeve and the right hand sleeve are adapted to interconnect with one other by threadable engagement.

In preference, the left hand sleeve and the right hand sleeve have a flange positioned on an outer periphery that abuts an external face of the bottom bracket shell of the bicycle. In preference, the left hand side sleeve has a securing means to urge against an external face of the face of the bottom bracket shell of the bicycle.

In preference, the securing means is a lock ring.

BRIEF DESCRIPTION OF THE DRAWINGS

By way of example, an embodiment of the invention is described more fully herein with reference to the accompanying drawings, in which:

Figure 1 is a cross sectional view of the present invention;

Figure 2 is an exploded cross section view of the present invention adjacent a bottom bracket section of a bicycle.

Figure 3 is a cross section view of the present invention in a partially assembled state; Figure 4 is a cross section view of the present invention as in Figure 3 with the transmission fitted;

Figure 5 shows a cross section view of the present invention as assembled.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows the cross sectional view of a cylindrical bicycle bottom bracket adaptor 10, for insertion into a bottom bracket shell 11 of a bicycle, having a left hand side sleeve 12 and a right hand side sleeve 14. The size and shape of the sleeves 12 and 14 is cylindrical to fit within a bottom bracket shell of the bicycle without engaging any internal screw threads of the bottom bracket shell 11 if they are present.

Note that some bottom bracket shells do not require threads and as such the outer diameter of the adaptor 10 can be sized to fit nestingly into the bottom bracket shell with a press fit. Also, the width of the adaptor 10 can be varied to accommodate the varying widths of bottom brackets shells 11, such as English/ISO width, which varies between 68mm (standard) to 73mm (oversize), up to 83mm (for more rugged). Such adaptions to bottom bracket shell size are considered to be within the scope of the invention.

The bottom bracket shell 11 has a non-drive side 11a and a drive side lib, which relates to the side of the bottom bracket shell 11 to which the bicycle cranks are attached to.

The left hand side sleeve 12, which is inserted into the non-drive side 1 la of the bottom bracket shell 11, has a threaded end 16 that mates with the threaded end 18 of the right hand side sleeve 14, which is inserted into the drive-side 1 lb of the bottom bracket 11. The thread direction of the threaded ends 16 and 18 are such that the ride hand side sleeve 14 is engaged with the left hand side sleeve 12 by clockwise rotation (right hand thread).

The right hand side sleeve 14 has a thread 20, on the interior face 21, being a normal right hand thread, located close to the periphery of the opening 23. The positioning of the right hand thread 20 on the face 21 allows for the insertion and engagement of a derailleur mechanism 30, which has a threaded end 32 having a right hand thread 33. Again, as with the sleeve 12 and 14, a clockwise rotation of the right hand thread 32 of the derailleur 30 tightens the derailleur to the right hand side sleeve 14 of the bottom bracket adaptor 10.

Both left and right hand side sleeves (12 and 14) have a flange (26 and 27) projecting outwards about the periphery of the sleeves. These flanges (26 and 27) abut against the outer surface 11c and lid of the bottom bracket shell 11 when the left and right side sleeves (12 and 14) are tightened to one another.

The flange 26 on the left hand side sleeve 12 can be created by the use of a lock ring 25 attachment having an internal thread for engagement with a threaded outer section 28of the left hand side sleeve 12. This allows for precession tightening of the bottom bracket adaptor 10 when assembled in the bottom bracket shell 11.

Bearings 36 and 38 are housed within the bottom bracket shell 11 positioned to accept the spindle 40, which is connected to the bicycle cranks (non drive side crank arm 41 and drive side crank arm 42 having chain rings 44. The bearings 36 and 38, support the spindle 40 in the bottom bracket shell 11 and allow it to rotate with very little friction. During normal riding, in which the rider rotates the cranks 41 and 42 in a clockwise (right) motion. The derailleur 30 is connected onto the right side sleeve 14 and as the cranks are rotated the torque generated is transmitted from the cranks (41 and 42) to the derailleur 30 then through to the right and left sleeve 12 and 14 of the bottom bracket adaptor. As all the threads connecting these parts are right hand then the threads are placed under load and tightened. As such the parts do not have the opportunity to become loose and potentially come undone as is the case with left hand thread parts currently being used in bottom brackets for bicycles.

This then represents a significant development to the bicycle bottom bracket system and allows bicycle manufactures to continue to use standard threaded bottom brackets standards such as English/ISO left hand thread fittings in the drive-side of a bottom bracket shell but also allows for the fitting of the bottom bracket adaptor 10 of the present invention to allow the insertion and use of derailleurs of the type shown herein without having the drawbacks experienced from standard bottom bracket threading.

This practical new model introduces a mechanism that can change the threading direction of the bottom bracket right side of a bicycle. Hence, the original left-hand thread on the bottom bracket sleeve is changed to right-hand thread; it can bear the force transferred from the bike pedals through the cranks.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures can be made within the scope of the invention, which is not to be limited to the details described herein but it is to be accorded the lull scope of the appended claims so as to embrace any and all equivalent devices and apparatus.

Claims

Cylindrical cradle adapter for a bicycle, the adapter comprising a cuff located on the left and a cuff located on the right, both of which are of such size that they fit within a bicycle cradle bush, the cuff located on the left and the cuff the cuff located on the right-hand side is adapted to be connected to one another, characterized in that the cuff located on the right-hand side has an internal right-handed thread suitable for screwable engagement with a crank mechanism with internal transmission.

2. An adapter according to claim 1, further characterized in that the left-hand cuff is inserted into the non-driven (left) side of a bicycle bearing bush and the right-hand cuff is inserted into the driven (right) ) side of the bottom bracket, and that the two cuffs are then screwed together.

An adapter according to claim 1 or 2, further characterized in that the sleeve located on the left-hand side and the other right-hand side cuff are adapted to be connected to each other by means of screwable engagement.

An adapter according to claim 3, further characterized in that the cuff located on the left-hand side and the other right-hand side cuff have a flange located on an outer circumference which abuts against an outer surface of the bicycle bearing bush.

An adapter according to claim 4, further characterized in that the cuff located on the left-hand side has securing means suitable for exerting force with respect to an outer surface of the surface of the pedal-bearing bush of the bicycle.

Adapter according to claim 5, characterized in that the securing means comprise a locking ring.