Bicycle suspension
The bicycle suspension is a vehicle suspension that is used to protect cyclists and bicycles from impacts and vibrations in contact with the ground. The most common are bicycle suspensions on mountain bikes and hybrid bikes (e-mountain bikes).
Even with unsprung bicycles, the tires, forks and frames absorb some of the shocks and vibrations and have a dampening effect through self-bending ("flexing"). Such flexure joints can be supplemented with freely movable bearings and additional springs. The suspension can be attached to the front wheel, the rear wheel or the seat post . Bikes that only have suspension on the front wheel are called hardtails . In addition, spring-loaded on the rear wheels are called "full suspension" (eng. Fully hereinafter). Bikes with rear suspension are usually full suspension. Unsprung are basically racing bikes , Crosser , triathlon wheels or input gears ( fixed gear ).
A bicycle with a suspension is more comfortable to ride, especially on unpaved surfaces and poor roads. It also has higher traction and increased driving safety , as the wheels have more frequent and constant contact with the ground. Disadvantages are the higher weight, the higher purchase price and greater maintenance costs.
history
At the transition from the high bike to the safety low bike, options were sought to improve the lower level of driving comfort due to the reduction in size of the bikes. In 1885 the Whippet from the Safety Bicycle brand appeared, which already used simple spring constructions to spring the frame.
In 1985 Horst Leitner developed a mountain bike prototype with the Horst-Link , later named and patented after him , the first form of the classic four-bar linkage . A company founded by Leitner called AMP began making full-suspension mountain bikes. In 1990 AMP presented the first completely independent seesaw in the rear end system for mountain bikes.
Rear wheel suspension
General
Suspension and damping
The rear spring element is usually referred to colloquially as a "damper", although it is basically a combined spring strut with a spring and shock absorber in one unit. The rear wheel is resiliently supported on the frame via the rotatable rear structure via this strut. As actual chassis spring either a steel is coiled spring (Engl. Coil ) - usually with wheels with lots of travel or travel less than - air suspension realized. With the so-called air damper, the spring effect is achieved with air. Damping that is independent of the suspension controls the compression and rebound speed of the suspension and works hydraulically with all high-quality suspension elements in the mountain bike sector; the damping behavior can often be adjusted in the rebound and compression stages. High-quality spring elements often allow spring movements to be blocked in a targeted manner by means of "overdamping" in order to prevent unwanted deflection and compression when pedaling ( lock out ).
Suspension travel
The spring travel describes the total travel available for the wheels in relation to the frame. Suspension travel in downhill sports is approx. 200 millimeters, in " all mountain (enduro)" sports 140 to 180 mm and in cross-country sports around 80 to 100 mm. The negative spring deflection ( sag ) is the distance that the fork is immersed in under static load due to the weight of the rider when sitting calmly in the saddle. It is the way that the fork and shock absorber - for example when driving over a bump - can still rebound without the tires losing contact with the ground.
Spring stiffness
The spring stiffness is a measure of the compression depth for the same rider weight. In the case of steel spring forks / dampers, the spring stiffness can only be adjusted to a limited extent via their preload or an air support. Otherwise it is necessary to replace the spring: Heavy riders need stiffer springs than light ones. With air suspension forks / dampers, the spring stiffness can be adjusted much more easily by varying the air pressure with the help of a pump: more pressure corresponds to a harder spring. Due to the spring stiffness, the desired negative spring travel can be adjusted to the rider's weight.
Designs
There are numerous designs for the rear end, which differ in terms of their kinematics , dimensions and price.
Single pivot
The single pivot is the simplest construction. The rear axle of the bicycle is connected to the bicycle frame with a central pivot bearing . The entire rear end moves back and forth on an arc around this joint . The joint is usually located near the bottom bracket . The chainstay and dropouts are firmly connected.
The impulse is transmitted without resistance via the joint, which makes the damper very sensitive, but also susceptible to pedaling when the rider is not in the saddle: This can result in additional lateral forces that damage the damper. For the designation single-joint, further joints are not counted if these only serve to support lateral forces (supported single-joint / multi-joint). Due to the very simple design, many manufacturers use this type as a cheap basic platform.
Four-bar linkage
The rear axle is connected to the frame with two joints, with one joint between the chain stay and dropouts , the so-called Horst link . The remaining joints are used for support. This causes the rear wheel to compress in a more even, straight motion. In addition, the influence of the drive and brakes on the rear end is reduced by the additional bearings. On the other hand, each additional bearing results in higher costs and weight as well as greater wear.
The bicycle manufacturer Specialized appropriated several patents from Leitner, which he used for his famous FSR rear end. Many companies licensed this design. European companies like Cube and Scott used the same design, but were unable to distribute it to the US market until 2013 due to patent rights. Norco Bicycles, a Canadian bike manufacturer, also acquired the design from Specialized, but developed it further and has since sold it under the name Advanced Ride Technology (ART)
VPP rear end
VPP ( Virtual Pivot Point ) means something like "virtual pivot point". Two bearings are close together between the chainstay and the frame . This creates an imaginary fulcrum around which the rear wheel rotates during compression. There are two more bearings on the damper linkage. This design reduces bobbing while pedaling in the saddle to a minimum.
Suspension of the front wheel
The suspension of the front wheel is carried out by a suspension fork (opposite: rigid fork). Front suspension has been more common since the 1990s. The designs include v. a.
The suspension takes place either via steel springs, elastomers or air suspension. An oil damper is usually used to dampen the vibrations that occur in the suspension. There are also air-cushioned forks and friction dampers.
Suspension of the seat post
literature
- Michael Gressmann, Franz Beck, Rüdiger Bellersheim: specialist knowledge of bicycle technology. 1st edition, Verlag Europa Lehrmittel, Haan-Gruiten 2006, ISBN 3-8085-2291-7
- Michael Gressmann: Bicycle Physics and Biomechanics. Technology, formulas, laws. 11th edition, Delius Klasing Verlag, Bielefeld 2010, ISBN 978-3-7688-5222-7
- Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production. 10th edition, BVA Bielefelder Verlagsanstalt GmbH & Co. KG, Bielefeld 1999, ISBN 3-87073-131-1
Individual evidence
- ^ David V. Herlihy : Bicycle: History . Yale University Press, 2004, ISBN 0-300-10418-9 , p. 246: "The popular Whippet incorporated a series of external springs suspending the entire frame."
- ^ Wiebe E. Bijker: Of Bicycles, Bakelites, and Bulbs: Toward a Theory of Sociotechnical Change . The MIT Press , 1997, p. 73: "Even the successful" Whippet "with its many movable parts needed more attention than an ordinary bicycle."
- ^ Tony Hadland and Hans-Erhard Lessing: Bicycle Design, An Illustrated History . MIT Press , 2014, ISBN 978-0-262-02675-8 , p. 207: “The Whippet bicycle of the mid 1880s had the whole section of the frame carrying the handlebars, the seat, and the cranks sprung as a single unit . "
- ↑ US patent US000005509679A . Depatisnet. Retrieved June 28, 2016.
- ↑ US patent US000005509679A . Depatisnet. Retrieved June 28, 2016.
- ^ History of AMP Research . AMP Research. Archived from the original on October 19, 2007. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved June 28, 2016.
- ↑ Horst Leitner: Rear suspension for bicycles US5678837 . Retrieved June 3, 2016.
- ↑ Horst Leitner: Rear suspension for bicycles US5509679 . Retrieved June 3, 2016.
- ↑ Scott USA Genius . Archived from the original on February 20, 2009. Retrieved June 28, 2016.
- ↑ EXPLAINING ADVANCED RIDE TECHNOLOGY - ART . Archived from the original on July 14, 2014. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved June 28, 2016.
- ↑ Bike Test: Norco Range 2 . The Enthusiast Network. Retrieved June 28, 2016.
- ↑ US Patent RE39159 - Bicycle wheel travel path for selectively applying chainstay lengthening effect . Retrieved May 28, 2016.
- ↑ Hayes, Simon Young: Buyer's guide to mountain bike suspension, part 2 . Retrieved May 20, 2016.
- ^ The Virtual Pivot Point . In Kenneth M. Sasaki: A Bicycle Rear Suspension Analysis Method , 2001. Retrieved May 20, 2016
