Motorcycle fork
![](http://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Bmw-telescopic.jpg/220px-Bmw-telescopic.jpg)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Honda-rune.jpg/220px-Honda-rune.jpg)
A motorcycle fork connects a
The fork and its attachment points on the frame establish the critical geometric parameters of
Variations
A variety of fork arrangements have been tried during more than one hundred years of motorcycle development, several of which remain available today.
Telescopic
![](http://upload.wikimedia.org/wikipedia/commons/thumb/c/ca/R12-fork.jpg/220px-R12-fork.jpg)
A
Conventionally, the fork
Trailing link
A trailing link fork suspends the wheel on a link (or links) with a pivot point forward of the wheel axle. Most famously used by
Leading link
![](http://upload.wikimedia.org/wikipedia/commons/thumb/5/5f/Ural-fork.jpg/220px-Ural-fork.jpg)
A leading link fork suspends the wheel on a link (or links) with a pivot point aft of the wheel axle. Russian Ural motorcycles used leading link forks on sidecar equipped motorcycles, and aftermarket leading link forks are often installed today on motorcycles when they are outfitted with sidecars. They are also very popular with trikes, improving the handling while steering or braking. The most common example of a leading link fork is that found on the Honda Super Cub.
Springer
![](http://upload.wikimedia.org/wikipedia/commons/thumb/3/35/Harley-Davidson_9.jpg/220px-Harley-Davidson_9.jpg)
The springer fork is an early type of leading link fork. A springer fork does not have the suspension built into the fork tubes, but instead has it mounted externally, where it may be integrated into the triple clamp. This style of fork may be found on antique motorcycles or choppers, and is available today on Harley-Davidson's Softail Springer.
While it may have an exposed spring near the triple clamp, a springer fork is distinguishable from a girder fork by its two parallel sets of legs. The rear is firmly fixed to the bottom triple clamp (usually brazed or welded). A short leading link holds the wheel and the forward leg which actuates the springs (usually mounted on the triple clamp).
Earles
![](http://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Douglas-fork-1952.jpg/220px-Douglas-fork-1952.jpg)
The Earles fork is a variety of leading link fork where the pivot point is behind the front wheel, which is the basis of the Earles' patent.
Girder
![]() | This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: incorrect use of (American jargon) telescopic fork terminology not applicable to Girder forks. (March 2016) |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Cotton-fork.jpg/220px-Cotton-fork.jpg)
One of the earliest types of motorcycle front suspension, the girder fork consists of a pair of uprights attached to the triple clamp by linkages with a spring usually between the top and bottom triple clamps. The design reached a peak in the "Girdraulics" used on Vincent motorcycles from 1948. Girdraulic forks featured hydraulic damping with forged alloy blades providing extra strength.[4]
While both may have an exposed spring near the triple clamp, a girder fork is distinguishable from a springer fork by the wheel being fixed firmly to the (usually a long diamond shape) upright. The pivot points are short links mounted to the top and bottom triple clamps. The spring is usually mounted to the girder and compressed against the upper triple clamp.
Although girder forks are associated with early motorcycles, the British Ariel Ace, a modern sports motorcycle, has an alloy space frame and a matching girder fork. This Ariel girder fork is just as prone to brake dive as any telescopic fork, but is claimed to be more resistant to torsional twisting.
Saxon-Motodd (Telelever)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/3/36/BMW_R1150R_no_logo.jpg/220px-BMW_R1150R_no_logo.jpg)
The Saxon-Motodd fork (marketed as Telelever by
Hossack/Fior (Duolever)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Duolever600.jpg/220px-Duolever600.jpg)
The Hossack/Fior fork (marketed as Duolever by
.Coaxial steering front suspension
Developed by MotoCzysz for their C1 and awarded United States Patent 7111700 on September 26, 2006. Defined as a motorcycle or bicycle front end having coaxial steering and suspension components, and having telescopic forks. Swing weight of the forks is dramatically reduced by removing their suspension components to the central location, coaxially within the steering tube. Ride height can be adjusted without loosening the forks in the triple clamps. [7]
This particular fork, as implemented on the MotoCzysz C1, also has adjustable trail, from 89 mm to 101 mm.[8]
Non-forks
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Omega_shaped_chassis.jpg/220px-Omega_shaped_chassis.jpg)
There have been several attempts to implement front steering and suspension without using anything that could be described as a "fork". Examples include
A single-sided girder "fork" was used by the German firm Imme[12][13] between 1949 and 1951.[13]
Mead & Tomkinson Racing competed in endurance racing in the 1970s with "Nessie," a Laverda-based racing motorcycle with hub-centre steering.[14]
See also
- Bicycle and motorcycle dynamics
- Bicycle and motorcycle geometry
- Bicycle fork
- Hub-center steering
- Suspension (motorcycle)
- Suspension (mechanics)
References
![](http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
- ^ Foale, Tony. "TO DIVE OR ..." Archived from the original on 2013-02-04. Retrieved 2006-12-08.
- ISBN 0-7513-0043-8.
- ^ a b GB patent 693646, Earles, Ernest, "Motor cycle front wheel forks", published 1953-07-01
- ^ Robert Smith (May–June 2011). "A Brief History of Girder Forks". Motorcycle Classics. Retrieved 2011-05-20.
- ^ Cossalter, V. "BMW Telelever and telescopic forks: which is better ?". Archived from the original on 2010-05-16. Retrieved 2012-04-07.
- ^ Hossack Design Retrieved 2014-03-16
- ^ "Coaxial steering and suspension for motorcycle".
- ^ "MotoCzysz". 2006. Archived from the original on 1 December 2006. Retrieved 2006-12-14.
- ISBN 0-600-31870-2.
- ^ Foale, Tony. "STEER FOR THE FUTURE". Retrieved 2006-12-09.
- ^ McClellan, Don. "The Bike, Yamaha USA". Archived from the original on 2007-05-28. Retrieved 2006-12-09.
- ISBN 0-7513-0206-6.
- ^ ISBN 0-7513-0206-6.
- ^ "Lot 417: The ex-Mead & Tomkinson, 1976 Laverda 1,000cc 'Nessie' Endurance Racing Prototype - Bonhams". Bonhams. 20 October 2007. Retrieved 3 February 2014.