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Title:
BICYCLE FRAME WITH IMPROVED MECHANICAL STRENGTH
Document Type and Number:
WIPO Patent Application WO/2004/005122
Kind Code:
A1
Abstract:
A bicycle frame (1) comprises a plurality of tube pieces (2, 3, 4, 7, 8) presenting a saddle tube (2), tubes (7, 8) defining a rear fork unit (5) and tubes (3, 4) connected to a head tube (10), a bottom bracket shell (15) being provided to house known members connected to pedals. At least one of said tube pieces (2, 3, 4, 7, 8) comprises at least one end portion (2A, 3A, 4A, 7A, 8A) of circular cross-section and at least one portion (2B, 313, 413, 713, 8B) of elliptical cross-section, said portion of elliptical cross-section (2B, 313, 413, 713, 8B) having transverse dimensions greater than those of the end portion of circular cross-section (2A, 3A, 4A, 7A, 8A), said at least one tube piece (2, 3, 4, 7, 8) being in one piece.

Inventors:
COLNAGO ERNESTO (IT)
Application Number:
PCT/EP2003/006063
Publication Date:
January 15, 2004
Filing Date:
June 10, 2003
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
COLNAGO ERNESTO E C S R L (IT)
COLNAGO ERNESTO (IT)
International Classes:
B62K3/04; B62K19/02; B62K19/06; B62K19/28; (IPC1-7): B62K3/04; B62K19/02
Domestic Patent References:
WO1999059865A11999-11-25
Foreign References:
CH266540A1950-01-31
FR2477495A11981-09-11
US20020030345A12002-03-14
US5624519A1997-04-29
Attorney, Agent or Firm:
Ripamonti, Enrico c/o Ing. A. Giambrocono & C. S.r.l. (Via Rosolino Pilo 19/B, Milan, IT)
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Claims:
CLAIMS
1. A bicycle frame (1) comprising a plurality of tube pieces (2,3, 4,7, 8) presenting a saddle tube (2), tubes (7,8) defining a rear fork unit (5) and tubes (3,4) connected to a head tube (10), a bottom bracket shell (15) being provided to house known members connected to pedals, characterised in that at least one of said tube pieces (2,3, 4,7, 8) comprises at least a first end portion (2A, 3A, 4A, 7A, 8A) of circular crosssection and at least one portion (2B, 3B, 4B, 7B, 8B) of elliptical crosssection, said portion of elliptical cross section (2B, 3B, 4B, 7B, 8B) having transverse dimensions greater than those of the end portion of circular crosssection (2A, 3A, 4A, 7A, 8A), said at least one tube piece (2,3, 4,7, 8) being in one piece.
2. A bicycle frame as claimed in claim 1, characterised in that the portion of elliptical crosssection is at least the second end portion (2B, 3B, 4B, 7B, 8B) of the tube piece (2,3, 4,7, 8).
3. A bicycle frame as claimed in claim 1, characterised in that the portion of elliptical crosssection (2B, 3B, 4B, 7B, 8B) is directly connected to the first end portion of circular crosssection (2A, 3A, 4A, 7A, 8A).
4. A bicycle frame as claimed in claim 1, characterised in that the tube piece with the circular portion and elliptical portion forms part of the rear fork unit (5) of the frame (1).
5. A bicycle frame as claimed in claim 4, characterised in that tube piece is a tube piece (7) of the lower fork of said rear fork unit (5) connected to the bottom bracket shell (15).
6. A bicycle frame as claimed in claim 4, characterised in that the tube piece is a tube piece (8) of the upper fork of said rear fork unit (5).
7. A bicycle frame as claimed in claim 1, characterised in that the tube piece with the circular portion and elliptical portion is the saddle tube.
8. A bicycle frame as claimed in claim 1, characterised in that tube piece with the circular portion and the elliptical portion is one of the tube pieces (3,4) connected to the head tube.
9. A bicycle frame as claimed in claim 1, characterised in that the tube piece with the circular portion and elliptical portion comprises a portion with increased transverse dimensions or a widened portion (17,24, 2K, 3K, 4K).
10. A bicycle frame as claimed in claim 9, characterised in that the widened portion (17,24, 2K, 3K, 4K) is positioned between the end portions (2A, 2B, 3A, 3B, 4A, 4B, 7A, 7B) of that tube piece (2,3, 4,7, 8) with said end portions of circular and elliptical crosssection.
11. A bicycle frame as claimed in claim 10, characterised in that the widened portion comprises an aperture (21) defined by opposing arms (22) connected together at their opposing ends (23) where said ends combine into a single piece.
12. A bicycle frame as claimed in claim 10, characterised in that the widened portion (17,24, 2K, 3K, 4K) is of overall circular crosssection.
13. A bicycle frame as claimed in claim 10, characterised in that the widened portion (17,24, 2K, 3K, 4K) is of overall elliptical crosssection.
14. A bicycle frame as claimed in claim 10, characterised in that the widened portion (17,24, 2K, 3K, 4K) is of overall flat crosssection on at least two of its opposing sides.
15. A bicycle frame as claimed in claim 9, characterised in that the widened portion lies at one end of the tube piece with both the circular and elliptical portion.
16. A bicycle frame as claimed in claim 15, characterised in that the widened portion is substantially of fork shape and comprises diverging elements (40,50) connecting said tube piece to the adjacent tube piece.
Description:
BICYCLE FRAME WITH IMPROVED MECHANICAL STRENGTH The present invention relates to a bicycle frame in accordance with the introduction to the main claim.

A bicycle frame is known to comprise a plurality of tube pieces which are interconnected (although forming overall a one-piece element or frame). In particular, a bicycle frame comprises a tube piece supporting the saddle (saddle tube), a rear fork unit with upper and lower forks (these latter connected to a usual bottom bracket shell and positioned below the saddle tube), and tube pieces terminating within a head tube and connected one to the saddle tube and the other to the bottom bracket shell.

Usually these tube pieces, which are hollow and formed by the most disparate methods, can be of metal or of composite material, for example carbon fibre.

An object of the present invention is to provide a bicycle frame which presents high mechanical strength while at the same time is able to well absorb the impacts received by the bicycle during its movement, so preventing their direct transfer to the user using the vehicle.

These and further objects, which will be apparent to the expert of the art, are attained by a bicycle frame in accordance with the accompanying claims.

The present invention will be more apparent from the accompanying drawing, which is provided by way of example and in which: Figure 1 is a side view of a first embodiment of a frame according to the invention; Figure 2 is an enlarged view of the frame of Figure 1; Figure 3 is a perspective view of a part of the frame of Figures 1 and 2; Figure 4 is a side view of a second embodiment of a frame according to the invention; and Figure 5 is a side view of a third embodiment of a frame according to the invention.

With reference to said figures, a bicycle frame is indicated overall by 1. It comprises a plurality of tube pieces 2,3, 4, and a rear fork unit 5 presenting pairs of tube pieces 7 and 8 defining a lower fork and an upper fork of said fork unit 5. This latter supports a bicycle rear wheel, not shown.

In detail, the tube piece 2 is the saddle tube, and the tube pieces 3 and 4 are tubes having a first end 3A, 4A connected to a head tube 10 and second ends 3B, 4B connected to the saddle tube 2. The tube piece 3 has one end fixed to a usual bottom bracket shell 15 which carries a usual pedal spindle (not shown).

Likewise, each tube piece 7 and 8 of the rear fork unit 5 presents a first end 7A, 8A associated with an element 18 for connection to an spindle (not shown) of the bicycle rear wheel. Each tube piece 7 has a second end 7B associated with the bottom bracket shell 15, whereas each tube piece 8 has a second end 8B fixed to the saddle tube 2.

According to the invention, at least one of the said tube pieces of the frame 1 is in one piece (in the sense that it comprises at least one external one-piece sleeve or sheath, even if it contains internally, at least as end portions, an insert for example of metal) and presents a shape of variable cross-section, having at least a first end of circular cross-section and at least one portion of elliptical cross-section. This latter has larger transverse dimensions than the circular portion and presents a lateral surface greater than that of the circular portion. By virtue of this shaping, said tube piece is mechanically more resistant to stress.

More specifically, in one embodiment of the invention, at least each tube piece 7 of the lower fork of the fork unit 5 presents that end 7B with a circular cross- section and that end 7A with a circular cross-section. The tube piece 7 also presents a widened or"split"internal portion 17 (that positioned between the ends 7A and 7B) split to form a (central) aperture 21 defined laterally by opposing arms 22 connected together at their ends 23 where these arms combine into a single piece.

In this manner the widened or split portion 17 presents a large lateral surface and contributes to making the tube piece 7 even more resistant to stresses and able to absorb to a considerable extent the stresses deriving from impacts suffered by the bicycle and prevent their direct transfer to the user positioned on said bicycle.

This portion 17 can have an overall circular, elliptical or flat cross-section on at least two of its opposing sides (as in Figure 3).

According to a different embodiment of the frame 1, each tube piece 8 has a differential shape, having at least its end 8A of circular cross-section and its end 8B of elliptical cross-section. Moreover, advantageously, the tube piece 8 also presents a"split"intermediate portion 24 with a central aperture 25 defined by arms 26 similar to the aforesaid arms 22.

By virtue of these embodiments of the frame, there is an increase in the lateral surfaces of each tube piece 7 or 8, resulting in increased comfort in using the bicycle by better absorbing the impacts which would otherwise be transferred to the back of the user.

According to the variant of Figure 4, at least one of the tube pieces 2,3 and 4 also presents the shape (with differential cross-section) of each tube piece 7.

In particular the tube piece 2,3 or 4 is in one piece and comprises a first end (for example that 2A close to the saddle, 3A or 4A close to the head tube 10) of circular cross-section and the second end (that 2B close to the bottom bracket shelf 15, that 3B or 4B) of elliptical cross-section.

The tube piece 2,3 or 4 can also comprise, as in the figure, a split portion 2K, 3K, 4K formed as the portions 17 or 24 of the tube pieces 7 or 8.

According to the variant of Figure 5, at least one of the tube pieces 3,4 or 7 presents a split portion in correspondence with an end 3A, 4A or 7B. This split portion is substantially of fork shape and comprises diverging elements 40 and 50 connecting said tube piece provided with said semi-split or fork portion to the adjacent tube piece.

In all the illustrated embodiments, each tube piece is in one piece in the aforesaid sense.

By virtue of the invention a bicycle is obtained with a degree of comfort and of mechanical resistance to stresses which are superior than those of known bicycles.