Editing Swingarm (section)

==Swingarm types==
Swingarms can be single or double sided, and have appeared in a variety of geometries.  Many single-sided also incorporate the driveshaft.

'''Swinging fork''' - the original version consisting of a pair of parallel pipes holding the rear axle at one end and pivoting at the other. A pair of [[shock absorber]]s are mounted just before the rear axle and attached to the frame, below the seat rail.

'''Cantilever''' - An extension of the swinging fork where a triangulated frame transfers swingarm movement to compress shock absorber/s generally mounted in front of the swingarm. The HRD-[[Vincent Motorcycle]] is a famous early form of this type of swingarm, though [[Matchless]] used it earlier, and [[Yamaha Motor Company|Yamaha]] subsequently. The [[Harley-Davidson]] [[Softail]] is another form of this swingarm, though working in reverse, with the shock absorbers being extended rather than compressed.

[[File:Guzzidrive.jpg|thumb|Moto Guzzi's ''CRDS'' variant of the parallelogram]]

'''Parallelogram''' - Was first introduced commercially in 1985 on the Magni "Le Mans". Magni called the system ''Parallelogrammo''.   Various parallelogram systems have been developed by other manufacturers.<ref name="Magni History">{{cite web | title=Magni history | work=Magni | url=http://www.magni.it/storia2.htm | access-date=2008-03-15}}</ref>

Whereas downward generated mechanical forces would cause a chain-driven bike to [[Bicycle suspension#Bob and squat|"squat"]] at the rear under acceleration,<ref>{{cite web|url=http://www.suspact.com/Anti_Squat.html|title=Motorcycle anti squat|last=SuspAct|website=www.suspact.com|access-date=20 April 2018}}</ref> the torque reaction of a shaft drive machine would induce the opposite, causing the seat (and rider) to rise upwards, a phenomenon known as [[Shaft effect|"shaft-jacking"]]. This anti-intuitive sensation can be disconcerting to riders, which parallelogram suspensions seek to neutralize.

[[File:2015 BMW R1200RT paralever.jpg|thumb|BMW's Paralever rear suspension on a 2015 R1200RT]]

BMW introduced its ''Paralever'' system on its 1988 R80GS and R100GS motorcycles, which adds a second link between the rear drive and transmission to allow the driveshaft to pivot along the same axis as the sprung rear frame. 

[[Moto Guzzi]] patented its ''Compact Reactive Drive Shaft'' system (Ca.R.C.), where the driveshaft is free to float into its structure, providing much softer feedback from transmission.{{cn|date=August 2020}} An upper arm serves as a guide to close the geometry of the suspension.{{what|date=August 2020}}

'''Extended swingarms''' - are often used by [[Motorcycle drag racing|drag racing]] motorcycles (called dragbikes) to keep their [[center of gravity]] as forward as possible, which reduces the tendency to [[wheelie]] at the start.

{{anchor|Single-sided swingarm}}
'''Single-sided swingarm''' - a suspension lying along only one side of the rear wheel, allowing it to be mounted to a hub like a car wheel. Also found on [[Scooter (motorcycle)|scooter]]s, where a robust chain case doubles as the swingarm linking the engine and rear wheel, single-sided swingarms need to be much stiffer and more heavily built than double-sided, to accommodate the extra torsional forces. Having a single mounting point guarantees proper wheel alignment.{{Citation needed|date=August 2011}}

Single-sided swingarms date from at least the late 1940s. In 1948, the [[Imme R100]] produced by [[Norbert Riedel]] of Germany had both a single-sided front wheel suspension as well as a single-sided rear swingarm that doubled as the exhaust pipe.<ref name="EYBNnVJan2012">{{cite web | url =http://www.motohistory.net/news2012/news-jan12.html | title =Outstanding German two-strokes we shouldn't forget: Part Four, the 1950s | first =Ralf | last =Kruger | date =2012-01-16 | work = Ed Youngblood's MotoHistory &ndash; Ed Youngblood's News & Views &ndash; January 2012 Archive | location =Inverness, FL USA | at =5th article down | archive-url = https://web.archive.org/web/20120516172123/http://www.motohistory.net/news2012/news-jan12.html | archive-date =2012-05-16 | url-status =live | access-date =2012-02-26 | quote =This enabled the longish exhaust pipe to double as a single-sided swing arm for the rear wheel!}}</ref>  In 1950 Moto Guzzi introduced the Galletto, a large-wheel step-through scooter.  In 1980, [[BMW Motorrad|BMW]] introduced its first single-sided swingarm on the [[BMW R80G/S|R80G/S]], the "Mono-lever", which was superseded by the "Para-lever" used currently.  [[Honda]] currently features this style of swingarm on the [[Honda VFR800|Honda VFR]].  [[Ducati]] has created several models featuring single swingarms, most notably the [[Massimo Tamburini]]-designed [[Ducati 916|916 series]]. While Ducati abandoned this style for the [[Ducati 999|999]], the company returned to it for the [[Ducati 1098|1098]] superbike in 2007, and it survives in the current [[Ducati 1199]].  The [[Triumph Sprint ST]] and [[Speed Triple]] also feature single-sided swingarms.<ref>{{cite web |url=http://www.triumphmotorcycles.co.uk/motorcycles/range/touring/sprint/2011/sprint-st |url-status=dead |archive-url=https://web.archive.org/web/20100623133956/http://www.triumphmotorcycles.co.uk/motorcycles/range/touring/sprint/2011/sprint-st |archive-date=2010-06-23 |website=www.triumphmotorcycles.co.uk |title=Sprint ST {{!}} Triumph Motorcycles}}</ref>

===Images===
<gallery>
File:Lambretta Model C 123cc 2 swingarm closeup.JPG|alt=The image shows the starboard side (right side when facing forward) of the suspension of a Lambretta Model C. The swingarm, spring/damper unit, and wheel are shown. |Right side Of a Lambretta Model C, showing swingarm and suspension.
File:Lambretta Model D 123cc - close-up of rear wheel - 20080302.jpg|alt=The image shows the port side (left side when facing forward) of a Lambretta Model C. The wheel and the lug nut are visible but there is no visible connection between the wheel and the rest of the scooter.|Left side, showing rear wheel with no visible suspension.
File:SprintST.jpg|[[Triumph Sprint ST]] with single-sided swingarm.
</gallery>