A horizontal dropout on a steel frame road bicycle converted to a single-speed. The non-replaceable derailleur hanger (below the axle) and an eyelet (above the axle) for mounting a fender or rack are now unused.

A vertical dropout on an aluminum frame mountain bike. The silver part is the replaceable derailleur hanger.

A bicycle dropout (or frame end and fork end) is a slot in a frame or fork where the axle of the wheel is attached. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A road bicycle is a bicycle designed for use on roads, as opposed to rough terrain. ... Single-speed mountain bike A single-speed bicycle is a type of bicycle with a single gear ratio. ... Image File history File links Download high resolution version (1119x1356, 286 KB) Beschreibung Description: Shimano XT Schaltwerk hinten (am Mountainbike) Source: Selbst fotografiert Date: created 21. ... Image File history File links Download high resolution version (1119x1356, 286 KB) Beschreibung Description: Shimano XT Schaltwerk hinten (am Mountainbike) Source: Selbst fotografiert Date: created 21. ... Image:Downhill Bike A cross country mountain bike race A hardtail mountain bike A mountain bike or mountain bicycle (abbreviated MTB or ATB (All Terrain Bicycle)) is a bicycle designed for mountain biking, either on dirt trails or other unpaved environments. ... Steel frame and carbon fiber fork of 2000 LeMond Zurich racing bicycle. ... bicycle fork A bicycle fork is the portion of a bicycle that holds the front wheel and allows one to steer. ... “Wheelset” redirects here. ...

On bicycles that do not have a derailleur or other chain tensioning device, rear horizontal dropouts allow adjustment of chain tension, and can accommodate a range of chain lengths or cog sizes. They were standard on most older derailleur bicycles from before the 1990s. They are also used by single-speed bicycles. An older multi-speed bicycle with horizontal dropouts can be readily converted into a fixed gear bicycle or fixed wheel bicycle. Horizontal dropout openings may face forwards or rearwards. Track bicycles traditionally have the opening facing rearwards (track ends) while road bicycles have forward facing dropouts. Mountain bicycle with Derailleur gears 9x multiple sprockets of a Derailleur gear Derailleur gears are a gear system commonly used on bicycles, consisting of a chain, multiple sprockets and a mechanism to move the chain from one sprocket to another. ... Single-speed mountain bike A single-speed bicycle is a type of bicycle with a single gear ratio. ... A fixed gear bicycle A fixed gear bicycle, also known as a fixie, is a single speed bicycle without a freewheel. ... A track bicycle A track bicycle is a type of fixed-gear bicycle specially designed for track cycling in a velodrome. ...

Rear vertical dropouts have the slot facing downwards. The advantage is that the wheel axle cannot slip forward compared with horizontal dropouts. The disadvantage is that on a bicycle without a rear derailleur but with vertical dropouts, the chain tension cannot be adjusted by moving the wheel forwards or backwards, and needs another means of chain-tensioning, by a derailleur, chain tensioner, or eccentric bottom bracket or rear hub. Fixed wheel bicycles cannot use any form of chain tensioning device, because the lower run of chain is pulled very tight when using the transmission as a brake. Example of using eccentric on steam engine In mechanical engineering, an eccentric is a wheel that rotates on an axle that is displaced from the focus of the circle described by the wheel; in other words, a mechanical motion that can operate either as a cam or a crank, depending... A square-taper cartridge bottom bracket. ... “Wheelset” redirects here. ...

In general, a modern bicycle frame intended for derailleur gears will have a vertical dropout, while one designed for singlespeed or hub gears will have horizontal dropouts. Derailleur gears are a variable ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets and a mechanism to move the chain from one sprocket to another. ... Single-speed mountain bike A single-speed bicycle is a type of bicycle with a single gear ratio. ... Hub gears or internal-gear hubs are a type of gear system used on bicycles. ...

Features

Derailleur hanger

The derailleur hanger or mech hanger is the part of the dropout that the rear derailleur attaches to. Derailleur gears are a variable ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets and a mechanism to move the chain from one sprocket to another. ...

Most non-steel framed bikes have a separate removable derailleur hanger, generally made from aluminium which is bolted to the dropout. These are intended as a cheap replaceable part so that in the event of an accident or mechanical problem that could damage the derailleur or frame, the derailleur hanger breaks or deforms instead. Sometimes a shear bolt which is designed as a weak point will also be used. There are dozens of different derailleur hangers available and one model is seldom interchangeable with another. Steel frame and carbon fiber fork of 2000 LeMond Zurich racing bicycle. ... Mountain bicycle with Derailleur gears 9x multiple sprockets of a Derailleur gear Derailleur gears are a gear system commonly used on bicycles, consisting of a chain, multiple sprockets and a mechanism to move the chain from one sprocket to another. ... Steel frame and carbon fiber fork of 2000 LeMond Zurich racing bicycle. ...

In general, steel-framed bikes do not have a removable derailleur hanger, because a steel dropout and hanger is stronger and therefore less likely to be damaged, and also it is more malleable and less likely to work harden during deformation and generally can be bent back into shape without breaking. Steel frame and carbon fiber fork of 2000 LeMond Zurich racing bicycle. ... For other uses, see Steel (disambiguation). ...

It is important for proper indexed shifting for the derailleur hanger to be properly aligned. The rear derailleur bolt hole must be close to parallel with the rear axle. If it is out of alignment, the rear derailleur will move not far enough, with respect to the rear sprockets, with each click. A special tool exists to detect and aid in correcting misalignment of the derailleur hanger. This article does not cite any references or sources. ... On a bicycle, the cassette or the freewheel is the set of rear sprockets that attaches to a hub on the rear wheel. ... Various bicycle tools have evolved over the years into specialized tools for working on a bicycle. ...

On frames with no derailleur hanger, a direct mount derailleur or derailleur with a hanger plate is used. These only fit bikes with forward-facing horizontal dropouts, and are held in place by a small bolt and the rear wheel axle. These have now been effectively superseded by the derailleur hanger.

Lawyer lips

Lawyer tabs or lawyer lips (technically positive retention devices) are tabs fitted to the front fork dropouts of bicycles sold in some countries (particularly the U.S.) to prevent a wheel from leaving the fork if the quick release skewer comes undone. They were introduced in response to lawsuits supported by experts including John Forester, in cases where incorrectly adjusted quick release wheels came out of the forks. Lawyer tabs are designed to compensate for the fact that many riders do not know how to operate a quick release properly: some riders treat them as a folding wing nut, and others do not tighten them enough for fear of snapping them or shearing the skewer (both are highly unlikely given the normal range of human strength). bicycle fork A bicycle fork is the portion of a bicycle that holds the front wheel and allows one to steer. ... A quick release skewer is a cam operated lever system used with a hollow axle for securing the wheels on a bicycle. ... John Forester (born 7 October 1929) is an American industrial engineer and a noted cycling activist who coined the term Effective Cycling. ... A nut is a type of hardware fastener with a threaded hole. ...

A side-effect is that the quick release, which was developed to allow the wheel to be removed without having to unscrew any components, no longer works as designed: the skewer must be unscrewed in order to remove the wheel (although tools do remain unnecessary). This means that the tension on refitting must be adjusted again. Some cyclists file off the lawyer tabs so the quick release works as originally intended.

A correctly secured quick release is unlikely to be ejected from the dropout in normal use where rim brakes are in use, although recently there has been some evidence, notably from James Annan, a British scientist working in Japan, suggesting that the moments in disc brake systems can cause quick-release front wheels to be ejected past the lawyer tabs. A small number of serious crashes have been put down to this cause. This is controversial, and the fork manufacturers have not admitted a fault, although there is some evidence that they may accept the principle, and advice on checking quick release tension has been strengthened. ^[1][2] A complete solution to ejection risk would involve mounting the front disc brake caliper in front of the fork blade rather than behind, as the reaction force on the disc would then be into, rather than out of, the fork-end. However, this would involve major retooling by fork and brake manufacturers. Linear-pull brake on rear wheel of a mountain bike Bicycle brake systems are used to slow down, or brake a bicycle. ... It has been suggested that this article or section be merged with torque. ... It has been suggested that this article or section be merged into Vehicle brake. ...

Eyelets

Dropouts may support one or more eyelets, small protruding tabs with holes, often threaded, to facilitate the mounting of racks and fenders. A bicycle rack is a device to which a bicycle can be securely attached to prevent theft. ...

Adjustment screws

Some rear, horizontal, forward-facing dropouts have small adjustment screws threaded through the very rear to aid in positioning the axle precisely. The screws may be fitted with springs to keep them from moving.^[3]

Chaintugs

Some rear, horizontal, rearward-facing dropouts have threaded devices ("chaintugs") to aid in setting the proper chain tension. These may be integral to the dropout or separate items. They work by holding the rear axle in an eye at the end of a threaded bolt. The bolt passes through a cap which fits over the open track end. Tightening the bolts on each side causes the axle to be pulled backwards towards the open track end, tensioning the chain. Chaintugs can also solve the problem of "axle creep" on hard-ridden fixed-gear bicycles, especially those with hard chromed track ends, which may not offer adequate grip for the serrated track nuts.^[4]

References