Bicycle gear lever
Shift lever is a collective term for switches of different designs for operating a gear shift on bicycles or mopeds .
history
Planetary gears have been used on tricycles since the 1880s. The first two-speed hub gears for bicycles were invented by the American Seard Thomas Johnson in 1895 and by the Englishman William Reilly in 1896. Reilly's two-speed hub was produced from 1898 by the company "The Hub". In 1902 Reilly designed a three-speed hub gear, which was patented under the name of his colleague James Archer and produced by the Sturmey-Archer company. Hub gears have been around since 1902, and this was invented by the Wanderer company. The first hub that was ready for the market was designed by the Sachs company in 1907 and is still used today in a modified form. The two-speed gearshift at that time was transformed into the torpedo 3-speed hub with coaster brake in 1924 , which is now sold by SRAM .
Derailleurs were invented from 1935. The derailleur gears of the 30s and 40s were still operated directly, i.e. without Bowden cables. The first unsuitable variants had boom controls. The derailleur had a metal rod with a lever on the other end. This was operated with the hands or the foot. The gearshift lever was basically just a metal rod that was used to turn the chain cage back and forth. The hub gears have always been operated by Bowden cable, and rotary shifter handles were common.
It was not until the early 1960s that people started moving the levers closer to the cyclist's hands. It was operated - to this day - via a Bowden cable . A lever is used to pull the Bowden cable that adjusts the rear derailleur or the derailleur . If you loosen the Bowden cable, a spring moves the switch cage in the opposite direction.
There are also hydraulically operated systems and electrical circuits.
Friction or index shift levers
In the case of friction levers, a certain degree of stiffness (friction) ensures that the spring in the rear derailleur or derailleur does not adjust the shift by itself. The driver not only has to use a certain amount of force when pulling the Bowden cable, but also when he wants to loosen the Bowden cable.
Index shift levers (also: indexed shift levers) engage in every gear. The cable retraction path for each shifting step depends on the distance between the sprockets and the gear ratio of the rear derailleur (which can be variable depending on the gear). There are two different basic designs: The actuating element remains in the new position after the switching process - analogous to the friction lever - or the actuating element returns to its starting position after each switching process. This is sometimes referred to as a trigger shifter . There are versions with a single actuating element or with a lever or actuating button for each of the two switching directions.
Around 1990 there were a number of derailleurs that indexed directly on the rear derailleur. The Shimano Positron (with exceptions) and the Sachs Commander should be mentioned here. Some used a Bowden cable that also transmitted pressure, others had quick-release fasteners between the rear derailleur and the appropriately assembled Bowden cable. Partly high mechanical effort, sometimes a lack of adjustment options and an often higher sensitivity to dirt in the long run are to be noted. This rear derailleur technology could not prevail.
In the past, hub gears were always indicated systems, since the mechanics can easily be damaged by inexact lever position. An exception is the NuVinci continuously variable hub gear and the Rohloff Speedhub 500/14 , which are indexed in the hub. In derailleur gears , friction shift levers were used until the mid-1980s, in which the correct position of the shift lever had to be estimated, “felt” or checked by looking at the chain.
Twist grip
This is the oldest type of gear lever, it was also used on motor-driven bicycles ( mopeds ). For decades they were forgotten, in 1990 they were rediscovered by the Campagnolo company in the "Bullet" design for ATBs (All Terrain Bikes). While the bullet handles are rotated as a whole, another design is characterized by a split handle. These grips are currently experiencing a renaissance on mountain bikes and touring bikes. The article designation "Grip Shift" from SRAM has become synonymous with twist grips.
Other companies (e.g. Rohloff ) also use rotary switch handles in which only part of the handlebar grip is turned.
Rotary handles are very easy to assemble and manufacture and are therefore almost exclusively found in the low-price sector. They can mainly consist of molded plastics and four or in the simplest case even only two parts. A visible gear display can be achieved by simply printing the gear numbers on the twist grip.
There are also high-quality versions that enable precise switching operations over the long term.
Twist grip switches are available as friction switches and in indexed versions. With many current circuits, the indexing is done under control, which makes it correspondingly complicated and expensive to manufacture. In this version, the Bowden cables must be manufactured more precisely, since they are also responsible for the switching precision. The only exception at the moment is a Rohloff shift hub, which is indexed in the gearshift.
Twist handles are significantly less prone to failure than other gear lever designs because they have no protruding parts that can get caught, bend or break off. The partially existing precision mechanics are well encapsulated inside the handle and not susceptible to dirt. Shifting operations can be carried out more intuitively, as there is only one control element per shift and you can shift all gears one behind the other.
Frame shift lever
This design was widespread on racing bikes , but is no longer common today. One or two shift levers are mounted in the upper third of the down tube on solder sockets or a clamp. Switching takes a comparatively long time because you first have to take your hand off the handlebars and reach down to operate it. There are designs as friction switches and indexed systems (since around 1985). One advantage is that the Bowden cables can be laid without a cover and therefore run with very little friction and are usually lighter than shift / brake levers.
Shift lever on the stem
From the 1980s to the mid-1990s, these shift levers were mainly used for indexed derailleur gears. They are similar to the frame shift levers and are i today. d. Usually no longer available new.
Thumb switch on the handlebar
With the first MTBs , indexed, switchable and non-indexed thumb shift levers appeared, which no longer made it necessary to change your grip. The comparatively compact, stable and mostly sensitively switchable levers were located above the handlebars. Simple thumb shift levers are still available in the aftermarket today.
Shift lever on the handlebar
Together with the rotary handles, this is the most common design. It is operated using small levers or buttons that are operated with the thumb or forefinger. Shift levers of this type are generally indicated. They are often combined with brake levers that are operated with the middle and ring fingers. So it is possible within certain limits to brake and shift at the same time. Shimano calls this form Rapid Fire .
Shift lever for the triathlon handlebar attachment
Triathlon bicycles have an attachment on the handlebars for storing the forearms so that the rider can ride in a stooped position for a longer period of time. There are special shift levers for the handlebar attachment. Frame switches attached with a clamp can also be used.
Handlebar end shifter
Common on cyclocross bikes since the 1960s. Later it was also used on touring and racing bikes - mainly on triathlon handlebar attachments. They have also been available as index levers since the 1980s (e.g. SunTour XC-Pro etc.). The indexing can be switched off on some levers (Shimano).
Brake shifter
This design has replaced the frame gear lever and established itself on racing bikes and similar bikes . Shimano has also been offering this switching option for mountain bikes since the 2003 model year . The gearshift is operated by tilting the brake handles sideways or by using an additional lever directly behind the brake lever. Brake shift levers are comparatively expensive and have a complex interior. Repairs are therefore time-consuming and sometimes even impossible. Shifting is more convenient as there is usually no need to change your grip. Due to the longer Bowden cables and sleeves, modifications to the geometry of the parallelograms of the rear derailleurs were necessary. As a result, older rear derailleurs with brake / shift levers only work to a limited extent or not at all.
In 2009 Shimano launched the Di2, the first fully electronically controlled drive group with digital pushbuttons in the Bems gear lever. Campagnolo ( EPS) and SRAM ( SRAM Red eTap ) followed suit with their own systems.
literature
- Rob van der Plas: The bicycle workshop - repair and maintenance step by step. 1st edition, BVA Bielefelder Verlaganstalt, Bielefeld, 1995, ISBN 3-87073-147-8
- Jörg Urban, Jürgen Brück: Bicycle repairs, maintenance and breakdown assistance. 1st edition, Gondrom Verlag GmbH, Bindlach, 2007, ISBN 978-3-8112-2938-9
- Christian Smolik , Stefan Etzel: The new bicycle repair book. Bielefelder Verlagsanstalt 1999, 9th edition 2010, ISBN 3-87073-055-2 .
- Richard Hallet: Bicycle Maintenance-Care-Repair. 1st edition, BVA Bielefelder Verlag GmbH & Co. KG, Bielefeld, 2003, ISBN 3-87073-308-X
- Peter Barzel, Michael Bollschweiler, Christian Smolik : The new bicycle technology: material, construction, production. Bielefelder Verlagsanstalt, 2008, ISBN 3-87073-322-5 .
Footnotes
- ^ A b Tony Hadland: The Sturmey-Archer-Story . Pinkerton Press, Birmingham 1987, ISBN 0-9507431-2-7 .
- ↑ 1902 - first German patent for a gear hub from Wanderer
