Patent Application
20110115192
The present invention pertains to the field of bicycles. More particularly, the present invention pertains to bicycle frames.
A bicycle frame is the main component of a bicycle and upon which all other components are fitted. The most common frame design for an upright bicycle is called a diamond frame, consisting of a pair of triangles, the main triangle and the rear triangle, and is the type of frame generally used for heavy duty bicycles, such as mountain bikes.
In a diamond frame, the main triangle consists of the head tube, top tube, down tube and seat tube. The rear triangle consists of the seat tube, paired chain stays, and paired seat stays. The top tube connects the head tube to the seat tube at the top of the frame, and the down tube connects the head tube to the lower end of the seat tube. Paired forks attach the front wheel to the head tube. The rear triangle consists of the seat tube and a pair of chain stays and a pair of seat stays. The paired chain stays run parallel to the chain, connecting the lower seat tube to the back wheel. The paired seat stays connect the upper end of the seat tube (often at or near the same point as the top tube) to the paired chain stays at the back wheel.
Although frame tubing generally has a hollow central core, cabling for the bicycle components are commonly routed along mounts on the top and down tubes. Most commonly, this includes the cable for the rear brake, but some mountain bikes also route the front and rear derailleur cables along the outside of the top tube. On racing bicycles and some mountain and hybrid bikes, the derailleur cables typically run along the down tube. While such arrangements are advantageous to the manufacturing process, there is a downside: attaching cabling to the tube exterior subjects the cabling to physical damage from the elements or from rough treatment of the bike.
A heavy duty bicycle frame has specific requirements and design challenges. The frame must be strong and durable, and yet as light as possible. It must be comfortable to ride, mount and dismount, and ideally be made of materials that make the bike affordable.
Generally, tubing used for diamond frames are made of steel, aluminum, titanium, metal alloys, or carbon fiber. Of these materials, metallic materials such as steel, aluminum and their alloys are most desirable for use in a heavy duty bicycle frame, as they are strong, affordable and easy to work with.
Comparing steel and its alloys such as chromium-molybdenum, or “chromoly” with aluminum and its alloys, the main drawback of steel (and its alloys) is that it is much heavier than aluminum (and its alloys), and methods used to decrease the weight, such as butting, in which the ends of the tubes are thicker than the central portions of the tubes, increases cost and manufacturing complexity. Aluminum and its alloys have an attractive strength-to-weight ratio compared to steel and its alloys, but an aluminum tube's optimal wall thickness-to-diameter ratio requires oversized tubing, in order to achieve acceptable yield strength, elongation limits, and durability. While the resulting frame tubing is significantly stiffer and lighter than steel, it is of a larger diameter, and is thus more bulky.
What is needed, then, is a heavy duty bicycle frame that is strong, durable, and affordable, and that can house, internally, cabling and other electrical components, and that has a profile that makes the frame easy to mount/dismount, and so is less bulky than a frame of simple aluminum tubing.
The invention provides a bicycle frame including at least either a top tube or a down tube made from an extrusion having a webbed interior space. Such webbing provides both structural strength to the frame tubing and also provides internal compartments for housing mechanical and electrical cabling, protecting such cabling from physical damage as well as keeping the cabling organized and untangled.
The features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with accompanying drawings, in which:
The following is a list of reference labels used in the drawings to label components of different embodiments of the invention, and the names of the indicated components.
The invention provides a bicycle frame interchangeable with the prior art bicycle frame shown in
Referring now to
Referring now again to
Each tube 1214 and the partitions 20 forming its interior webbing are typically manufactured as a single piece of extruded aluminum or alloy thereof, but may instead be made of extrusions of other high strength, lightweight metallic materials, such as tungsten and/or tungsten alloys. The extrusion method of manufacturing the tubes is typically used because it allows the webbed interior and the exterior tube to be made as a single piece.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention.
