Fork stabilizer

Egli-Honda with fork stabilizer

A fork stabilizer is a connection of the telescopic fork between the fork bridge and the axle mount of the front wheel on the motorcycle .

History and technology

Already in the 1950s with the Zündapp KS 601 there was a rigid connection between the fork tubes to accommodate the central damper. In the 1970s, telescopic forks with a small stanchion tube diameter and thus insufficient torsional rigidity were common on sporty motorcycles. In 1969, Honda had a standpipe diameter of 35 mm for the Honda CB 750 Four, similar to BMW later for the BMW R 90 S , while 46 mm represents the state of the art in comparable motorcycles today (as of 2013).

"The torsional stiffness of the fork is crucial for the stable and sway-free wheel guidance in the higher speed range. [...] The insufficient torsional stiffness of the fork is one of the main causes of the dreaded high-speed oscillation."

- Helmut Werner Bönsch: Progressive motorcycle technology, p. 228

In order to increase the torsional stiffness of the telescopic fork, Fritz Egli developed his Egli Racing fork in the 1970s, in which the fork legs were also connected to a tubular steel bridge. At the beginning of the 1980s, material-reinforced fenders were offered by Japanese manufacturers, and later fork stabilizers that could be retrofitted. With the reintroduction of the upside-down fork by the Dutch manufacturer White-Power , the fork stabilizer lost its justification for this technology. The classic telescopic fork can still be retrofitted today. When retrofitting, it must be ensured that there is no voltage, as tilting changes the response behavior of the fork and leaky Simmerrings can result.

literature

Helmut Werner Bönsch: Advanced motorcycle technology. Motorbuch Verlag Stuttgart, 1st edition 1985, ISBN 3-613-01054-2 .
Jürgen Stoffregen: Motorcycle technology: basics and concepts of engine, drive and chassis. Vieweg Verlag, Braunschweig, 7th edition 2010, ISBN 978-3-8348-0698-7 .

Web links

Perch fork
Fork stabilizer, retrofitting ( memento from December 19, 2013 in the Internet Archive )
Fork stabilizer, retrofitting

Individual evidence

^ Helmut Werner Bönsch: Introduction to motorcycle technology. 3. Edition. Motorbuch Verlag Stuttgart 1981, ISBN 3-87943-571-5 , p. 52
↑ For example, increasing the standpipe diameter from 39 to 43 mm increases the bending stiffness by 40 percent. See Stoffregen, p. 294
^ Ulrich Hoffmann : The great lexicon of motorcycle technology. Heel Verlag, 2009, ISBN 978-386852-090-3 , p. 123

[1] Helmut Werner Bönsch: Introduction to motorcycle technology. 3. Edition. Motorbuch Verlag Stuttgart 1981, ISBN 3-87943-571-5 , p. 52

[2] For example, increasing the standpipe diameter from 39 to 43 mm increases the bending stiffness by 40 percent. See Stoffregen, p. 294

[3] Ulrich Hoffmann : The great lexicon of motorcycle technology. Heel Verlag, 2009, ISBN 978-386852-090-3 , p. 123