GB2494874A - Frame with split seat tube - Google Patents

Frame with split seat tube Download PDF

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Publication number
GB2494874A
GB2494874A GB1116270.8A GB201116270A GB2494874A GB 2494874 A GB2494874 A GB 2494874A GB 201116270 A GB201116270 A GB 201116270A GB 2494874 A GB2494874 A GB 2494874A
Authority
GB
United Kingdom
Prior art keywords
text
tube
frame
wheelbase
seat
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB1116270.8A
Other versions
GB201116270D0 (en
Inventor
Paul Simon Mackie
Andrew John Gowan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to GB1116270.8A priority Critical patent/GB2494874A/en
Publication of GB201116270D0 publication Critical patent/GB201116270D0/en
Publication of GB2494874A publication Critical patent/GB2494874A/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
    • B62K3/00—Bicycles
    • B62K3/02—Frames
    • B62K3/04—Frames having a substantially horizontal top bar
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
    • B62K3/00—Bicycles
    • B62K3/02—Frames
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
    • B62K19/00—Cycle frames
    • B62K19/02—Cycle frames characterised by material or cross-section of frame members
    • B62K19/04—Cycle frames characterised by material or cross-section of frame members the material being wholly or mainly metallic, e.g. of high elasticity
    • B62K19/10—Combinations of tube and sheet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
    • B62K19/00—Cycle frames
    • B62K19/30—Frame parts shaped to receive other cycle parts or accessories
    • B62K19/34—Bottom brackets

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Axle Suspensions And Sidecars For Cycles (AREA)
  • Automatic Cycles, And Cycles In General (AREA)

Abstract

A rigid bicycle frame arrangement comprising a split lower seat tube 9. This arrangement permits the use of a relatively short chain stay 5 resulting in a shortened wheelbase without compromising the geometry of the main members when using 29 inch diameter wheels. The split seat tube allows the rear wheel to partially enter the frame when rear wheel in brought forward reducing the chain-stay length and wheelbase. This arrangement permits desirable geometry of the frame members including seat tube angle, top tube length and seat tube offset. The shortened wheelbase of the bicycle using 29 inch diameter wheels results in desirable handling characteristics. The frame arrangement typically omits a front derailleur to allow the rear wheel to move into a forward position without fouling this mechanism.

Description

I
Eclipse Seat-tube 29er Frame Arrangement
Description
This invention relates to a rigid bicycle frame arrangement that comprises of main members: head-rube, top-tube, down-tube, upper seat-tuber lower split seat-tube, bottom bracket shell, chain-stays, seat-stays and dropouts. This arrangement for a bicycle frame is typically referred to as a double diamond' This invention relates specifically to a mountain bike frame which uses a 29 inch diameter front and rear wheel, sometimes referred to as a 29er' The 29 inch wheel mountain bike has gained increased popularity over the conventional 26 inch diameter wheeled mountain bike because of mechanical benefits such as: increased wheel inertia, larger tyre contact area with terrain and less rolling resistance to terrain obstacles such as roots and rocks.
However, the larger 29 inch wheel diameter compared to a conventional 26 inch wheel arrangement causes problems with the arrangement of the frame members, which in turn adversely affects rider positioning and maneuverability of the bicycle. Due to the size of the 29 inch wheel, the wheelbase of this type of bicycle is typically longer than that of an equivalent 26 inch bicycle. A bicycle with a longer wheelbase typically has a larger turning circle which in turn makes the handling of the bicycle in corners slower and less responsive.
Therefore, there is a need for a bicycle frame using 29 inch diameter wheels to have a shortened wheelbase to provide more responsive handling characteristecs.
Attempts have previously been made to accommodate a shorter wheelbase in a bicycle frame with 29 inch diameter wheels, although certain compromises in the frame arrangement needed to be made, as summarised below: 1. Offset seat-tube resulting in a shortened top-tube length.
2. Bent seat-tube resulting in a slack seat-Lube angle.
3. Shortened top-tube and down-tube to reduce the wheelbase of the frame.
4. Steepened head-tube angle.
The alterations to the frame arrangement listed above to accommodate the larger diameter 29 inch wheel with a shortened wheelbase drastically alter the positioning of the rider in an unfavourable fashion, sometimes compromising biomechanical efficiency.
Another factor to consider when attempting shortening of the wheelbase of a 29 inch bicycle frame is the position of the front derailleur mechanism. This mechanism has been favoured for many years end allows the rider to change gears at the crankset (i.e. the chain is moved from a smaller chainring to a larger chainring and vice versa by means of the front derailleur mechanism This mechanism has typically been developed with 26 inch wheel diameter frames in mind where there are sufficient clearances between the wheel and the mechanism. Shortening the wheelbase of a 29 inch wheeled frame typically results in shortening of the chain-stay length which in turn fouls the mechanism with the rear wheel.
The invention presented here is a rigid mountain bike frame arrangement which accommodates 29 inc diameter wheels with a shortened wheelbase without compromising the geometry properties of the frame which in-turn compromises the rider position on the bicycle.
This invention relates to a rigid mountain bike frame which does not employ a front derailleur mechanism and incorporates a unique split lower sear-tube arrangement which allows the rear wheel to be brought further forward than in a typical arrangement, thus shortening the wheelbase.
ft should be noted that omitting the front derailleur mechanism is not uncommon and many riders prefer to run a drive-chain arrangement which has a single chainring at the crankset.
The unique feature of this invention is the split lower seat-tube arrangement, dubbed eclipse seat-tube which maintains desirable geometry oroperties of the frame whilst allowing the rear wheel to be brought forward and reducing the wheelbase of the bicycle.
The split seat-tube could be made in a variety of arrangements. rhe arrangement presented here is two parallel plates of metal or aluminum consistent wsth the netal or aluminum used elsewhere on the frame which are separated by a gap approximate to the typical width of the tyre for the rear wheel of a 29 inch diameter mountain bike wheel. The length of the lower split seat-tube should be such that it allows the rear wheel to partially enter between the parallel plates.
The lower parts of the seat-tube plates connect to the bottom bracket shell.
It is desirable to have a wide bottom bracket shell to accommodate this fixing. The top of the seat-tube plates converge onto a conventional circular diameter seat-tube which the seat-post slides into in a conventional fashion.
Various materials typical to the construction of a rigid mountain bike frame such as steel, metal, alloy, aluminum or carbon-fibre could be used to produce the split seat-tube arrangement. The arrangement is not governed by a single material type.
An example of the invention will now be described by referring to the accompanying drawing: Figure 1 shows the primary elements which comprise a typical 26 inch diameter hardtail mountain bike with a conventional double diamond' frame, 1 Head-tube 2 -Top-tube 3 -Down-tube 4 -Seat-tube -Chain-stay 6 -Seat-stay 7 -Rear Dropout B -Front 26 Inch Diameter Wheel 9 -Front Fork (commonly a telescopic suspension type) -Stem (to which handibars connect) 11 -Seat Post 12 -Saddle 13 -Front Derailleur Mechanism 14 -Bottom Bracket Sheali -Crankset -Rear 26 Inch Diameter Wheel 17 -Dimension X': Wheelbase Measurement ff4ure2 shows the primary elements which comprise a typical 29 inch diameter hardtail mountain bike with a conventional double diamond' frame.
1 -Head-tube 2 -Top-tube 3 -Down-tube 4 -Seat-tube -Chain-stay 6 -Seat-stay 7 -Rear Dropout B -Front 29 Inch Diameter Wheel 9 -Front Fork (commonly a telescopic suspension type) -Stem (to which handlbars connect) 11 -Seat Post 12 -Saddle 13 -Front Derailleur Mechanism 14 -Bottom Bracket Shell -Crankset 16 -Rear 29 Inch Diameter Wheel 17 -Dimension Y' : Wheelbase Measurement. Note: Dimension Y Is typically greater than dimension X' shown in Figure 1.
Figure 3 shows the typical adjustments that are made in a bicycle frame to accommodate 29 inch diameter wheels and achieve a shortened wheelbase.
1 -Front 291 Inch Diameter Wheel 2 -Rear 29 Inch Diameter wheel 3 -Angle A' : Head Tube Angle Steepened 4 -Dimension 1' : Top-Tube Length Shortened -Angle B' : Seat-tube Angle Slackened 6 -Bend Introduced into Seat-tube 7 -Seat-tube Offset to Centre of Bottom Bracket Shell B -Fouling of the Front Derailleur Mechanism when Rear 29 Inch Diameter wheel Brought Forward 9 -Chain-stay Length Shortened -Dimension C': Shortened Wheelbase Figure 4 shows the invention presented here which accommodates a shortened wheelbase when using 29 inch diameter wheels whilst. Because of the unique split lower seat-tube the rear wheel is permitted to partially enter the frame when brought forward. Ihis unique feature allows retention of the other desirable frame geometry aspects without the compromises shown in Figure 3.
1 -Front 29 Inch Diameter Wheel 2 -Rear 29:nch Dianeter Wheel 3 -Angle 0' : Desirable Head-tube Angle 4 -Dimension B': Desirable Top-tube Length -Angle F' : Desirable Seat-tube Angle S -Upper Seat-tube 7 -Lower Split Seat-tube (dubbed Eclipse Seat-tube') B -Front Derailleur Mechanism Omitted 9 -Chain-stay Length Shortened -Rear 29 Inch Wheel Permitted to Partially Enter Frame 11 -Dimension C': Shortened Wheelbase Figure 5 shows a 3-0 image of the invention presented here. The 3-C image has been provided to more easily show the unique split lower seat-tube arrangement.
1 -Head-tube 2 -Top-tube 3 -Down-tube 4 -Bottom Bracket Shell -Chain-stay B -Rear Dropout 7 -Seat-stay B -Upper Seat-tube 9 -lower Split Seat-tube

Claims (1)

  1. <claim-text>Claims 1) A rigid bccycle frame arrangement that allows a shortened wheelbase when using 29 inch diameter wheels.</claim-text> <claim-text>2) Current rgid bicycle frame arrangements for 29 inch wheels have a longer wheelbase than a comparable 26 inch diameter bicycle; this longer wheelbase results in undesirable. handling characteristics which this invention seeks to resolve.</claim-text> <claim-text>3) Current rigid frame arrangements for 29 inch diameser wheels with a shortened wheeloase make compromises in the frame geometry which in-turn compromises the position of the rider and subsecuent biomechanioal action.</claim-text> <claim-text>4) This ir.ventinn has a unique split lower seat-tube arrangement which allows the rear wheel to be brought forward partially entering the seat-tube which results in a shortened wheelbase.</claim-text> <claim-text>5) The unique split lower seat-tube arrangement dubbed eclipse seat-tube' is not governed by a frame building material and can be made In a variety of shapes and configurations.</claim-text> <claim-text>6) The dimensions of the split sean-tube are such than they should allow nartial encompassment of the rear wheel when it is brought forward to produce a shortened wheelbase.</claim-text>
GB1116270.8A 2011-09-21 2011-09-21 Frame with split seat tube Withdrawn GB2494874A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1116270.8A GB2494874A (en) 2011-09-21 2011-09-21 Frame with split seat tube

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1116270.8A GB2494874A (en) 2011-09-21 2011-09-21 Frame with split seat tube

Publications (2)

Publication Number Publication Date
GB201116270D0 GB201116270D0 (en) 2011-11-02
GB2494874A true GB2494874A (en) 2013-03-27

Family

ID=44937591

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1116270.8A Withdrawn GB2494874A (en) 2011-09-21 2011-09-21 Frame with split seat tube

Country Status (1)

Country Link
GB (1) GB2494874A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014191706A1 (en) * 2013-05-30 2014-12-04 Bf1Systems Limited Improvements to bike frames

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB322877A (en) * 1928-11-23 1929-12-19 George Fraser Daycock Improvements in or relating to cycle frames
GB592920A (en) * 1945-06-12 1947-10-02 John Frederick Leete Improvements relating to cycles
CH261530A (en) * 1948-01-14 1949-05-15 Cappelletti Florio Bicycle frame.
FR2497756A1 (en) * 1981-01-13 1982-07-16 Motobecane Ateliers Frame for racing bicycle - has seat tube split at lower end with spaced connections to crank bracket
US4577879A (en) * 1983-09-19 1986-03-25 Vereyken Franciscus A Bicycle
EP0314601A2 (en) * 1987-10-29 1989-05-03 Simon Simon Molina Improved bicycle

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB322877A (en) * 1928-11-23 1929-12-19 George Fraser Daycock Improvements in or relating to cycle frames
GB592920A (en) * 1945-06-12 1947-10-02 John Frederick Leete Improvements relating to cycles
CH261530A (en) * 1948-01-14 1949-05-15 Cappelletti Florio Bicycle frame.
FR2497756A1 (en) * 1981-01-13 1982-07-16 Motobecane Ateliers Frame for racing bicycle - has seat tube split at lower end with spaced connections to crank bracket
US4577879A (en) * 1983-09-19 1986-03-25 Vereyken Franciscus A Bicycle
EP0314601A2 (en) * 1987-10-29 1989-05-03 Simon Simon Molina Improved bicycle

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Frame Option: Split Seattube", Wolfhound Cycles, 27/09/2007 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014191706A1 (en) * 2013-05-30 2014-12-04 Bf1Systems Limited Improvements to bike frames

Also Published As

Publication number Publication date
GB201116270D0 (en) 2011-11-02

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)