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Rohloff Speedhub
The Rohloff Speedhub is an epicyclic An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates the planet and sun gea ... internal hub gear for bicycles, developed and patented by Rohloff AG. It has been manufactured and marketed by that company since 1998. The Speedhub 500/14 has 14 equally spaced, sequential, non-overlapping gear ratios operated by a single twistgrip. The overall Bicycle gearing, gear range is 526%, meaning the highest gear is 5.26 times as high as the lowest gear. Individual gear shifts when shifting up give an increase of about 13.6% (equivalent to a decrease of about 12.0% when shifting down). The Speedhub is more expensive than competing bicycle gear systems (both hub gears and derailleur gears), and it is some 100 grams heavier than a comparable set of derailleur gears, but offers about t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ratchet (device)
A ratchet (occasionally spelled rachet) is a mechanical device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. Ratchets are widely used in machinery and tools. The word ''ratchet'' is also used informally to refer to a ratcheting socket wrench. __TOC__ Theory of operation A ratchet consists of a round gear or a linear rack with teeth, and a pivoting, spring-loaded finger called a '' pawl'' (or ''click'', in clocks and watches) that engages the teeth. The teeth are uniform but are usually asymmetrical, with each tooth having a moderate slope on one edge and a much steeper slope on the other edge. When the teeth are moving in the unrestricted (i.e. forward) direction, the pawl easily slides up and over the gently sloped edges of the teeth, with a spring forcing it (often with an audible 'click') into the depression between the teeth as it passes the tip of each tooth. When the teeth move in the opposite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1998 Introductions
1998 was designated as the ''International Year of the Ocean''. Events January * January 6 – The '' Lunar Prospector'' spacecraft is launched into orbit around the Moon, and later finds evidence for frozen water, in soil in permanently shadowed craters near the Moon's poles. * January 11 – Over 100 people are killed in the Sidi-Hamed massacre in Algeria. * January 12 – Nineteen European nations agree to forbid human cloning. * January 17 – The '' Drudge Report'' breaks the story about U.S. President Bill Clinton's alleged affair with Monica Lewinsky, which will lead to the House of Representatives' impeachment of him. February * February 3 – Cavalese cable car disaster: A United States military pilot causes the deaths of 20 people near Trento, Italy, when his low-flying EA-6B Prowler severs the cable of a cable-car. * February 4 – The 5.9 Afghanistan earthquake shakes the Takhar Province with a maximum Mercalli intensity of VII (''Very strong''). With u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hub Gears
A hub gear, internal-gear hub, internally geared hub or just gear hub is a gear ratio changing system commonly used on bicycles that is implemented with planetary or epicyclic gears. The gears and lubricants are sealed within the shell of the hub gear, in contrast with derailleur gears where the gears and mechanism are exposed to the elements. Changing the gear ratio was traditionally accomplished by a shift lever connected to the hub with a Bowden cable, and twist-grip style shifters have become common. Hub gear systems generally have a long and largely maintenance-free life though some are not suitable for high-stress use in competitions or hilly, off-road conditions. Many commuter or urban cycles such as European city bikes are now commonly fitted with 7-speed gear-hubs and 8-speed systems are becoming increasingly available. Older or less costly utility bicycles often use 3-speed gear-hubs, such as in bicycle sharing systems. Many folding bicycles use 3-speed gear-hubs. Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cogset
On a bicycle, the cassette or cluster is the set of multiple sprockets that attaches to the hub on the rear wheel. A cogset works with a rear derailleur to provide multiple gear ratios to the rider. Cassettes come in two varieties, freewheels or cassettes, of which cassettes are a newer development. Although cassettes and freewheels perform the same function and look almost the same when installed, they have important mechanical differences and are not interchangeable. Freewheels A freewheel (also known as a block) consists of either a single sprocket or a set of sprockets mounted on a body which contains an internal ratcheting mechanism and mounts on a threaded hub. Threaded rear hubs were available in different thread patterns depending on the country of manufacture, French and British threads being the most common. British C.E.I. (Cycle Engineers Institute) thread was adopted as the international standard and is now known as B.S.C. (British Standard Cycle). It is a standar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gear Inches
Gear inches is one of several relative measures of bicycle gearing, giving an indication of the mechanical advantage of different gears. Values for 'gear inches' typically range from 20 (very low gearing) via 70 (medium gearing) to 125 (very high gearing); as in a car, low gearing is for going up hills and high gearing is for going fast. 'Gear inches' is actually the diameter in inches of the drive wheel of a penny-farthing bicycle with equivalent gearing. Origin of the term When the high wheeler or penny-farthing was the "ordinary" bicycle form, the comparative diameter in inches of the driven wheel was an indication of relative speed and effort. A 60-inch wheel propelled a bicycle faster than a 50-inch wheel when both were cranked at the same cadence. The technology of the high wheeler imposed a natural limit—a 60-inch wheel was about the maximum size that could be straddled by ordinary sized legs. When "safeties" replaced "ordinaries," chains and sprockets allowed small whee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rohloff
Rohloff AG is a German company from Fuldatal near Kassel that manufactures hub gears, bicycle chains and tools that are known for their durability and high performance. The company’s logo is a black silhouette of a raven on a yellow background. History Rohloff AG was founded in 1986 and began by producing a high-tech and very expensive bicycle chain, the SLT 99. Sales of this chain generated revenues of €1m in 1991, and approximately €0,5m annually from 1992-1998. Development of Rohloff Speedhub 500/14 While at the Tour de France road race in France in 1994, the Rohloffs went bicycling on the beach in France. The bikes got stuck in the sand, and the primitive derailleur gear systems would not work. This triggered Bernhard Rohloff to develop a new internally geared hub. On the 1996 IFMA in Cologne, Rohloff announced a 14-speed gear hub with a weight of 1700 grams. At the time, the gear hub with the greatest number of speeds was the fragile 3700 gram 12 speed Sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sturmey-Archer
Sturmey-Archer was a manufacturing company originally from Nottingham, England. It primarily produced bicycle hub gears, brakes and a great many other sundry bicycle components, most prominently during their heyday as a subsidiary of the Raleigh Bicycle Company. In the past, it also manufactured motorcycle hubs, gearboxes and engines. The company was founded in 1902 by Henry Sturmey and James Archer under the guidance of Frank Bowden, the primary owner of Raleigh. In 2000, the assets and trademarks of Sturmey-Archer were sold to Sun Race of Taiwan which was renamed Sun Race Sturmey-Archer Inc. and production moved to Taiwan. Products All Sturmey-Archer gear hubs use epicyclic (planetary) geartrains of varying complexity. The AW is the simplest, using one set of planetary gears with four planets. The AM uses three compound planets with differently sized cogs machined from a common shaft to engage the gear ring and sun gear separately, while the close-ratio three-speeds, and h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shimano Alfine
Alfine is the name of a comfort and urban oriented product series by Shimano. It is mainly known for internally geared hubs, but includes also hydraulic disc brakes and levers, chain tensioners, dynamo hubs, cranksets, shift levers, and complete wheels. Alfine 500 The Alfine 500 group, first introduced at Eurobike in 2006, included the epicyclic hub gear SG-S500. The internal mechanical design of the gear hub was based on that of the Shimano Nexus Inter 8, with two stepped planetary series, 5th gear being 1:1 direct drive, thus offering 8 speeds with percent intervals of 22,16,14,18,22,16,14, and an overall gear range of 307%, yet in a more attractive design than the Nexus, with better seals allowing slightly greater ruggedness, more attractive auxiliary components such as e.g. a ratcheting trigger shifter similar to the high-end Shimano derailleur shifters, and a hub shell with splines for mounting a disc brake rotor of the center lock standard. These mechanisms are grease-lu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SRAM Corporation
SRAM LLC is a privately owned bicycle component manufacturer based in Chicago, Illinois, United States, founded in 1987. SRAM is an acronym comprising the names of its founders, Scott, Ray, and Sam, (where Ray is the middle name of the company's first CEO, Stan Day). The company is known for producing cycling components, including some internally developed, such as Grip Shift, EAGLE (1x12), DoubleTap, dedicated 1x11 mountain and their range of AXS drivetrains. The company grew organically and through acquisitions to become a cycling component brand, selling under the brands SRAM, Avid, RockShox, Truvativ, Quarq, Zipp, TIME Sport pedals, Hammerhead cycling computers, and Velocio cycling apparel. Their components are manufactured primarily in-house, in factories located in Portugal, Taiwan, China, and the U.S., and distributed and sold as Original equipment manufacturer (OEM) equipment and aftermarket components in markets globally. History As a start-up company, SRAM introduced t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sachs Elan
The Sachs Elan was an epicyclic internal hub gear for bicycles, developed and manufactured by the bicycle division of the German company Fichtel & Sachs. It was considered heavy and production units were plagued with quality issues. The gear hub was discontinued before the turn of the 2000 millennium. History The Elan was introduced in 1995 and manufactured until 1998. With its 12 speeds and an overall range of 339%DEALER TECHNICAL MANUAL , SRAM, 1999 it was the most advanced epicyclic hub gear at the time, and the first hub gear commercially available with more than 7 speeds. After took over ownership of the German bicycle component manufacturer, the Elan was sold under ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
