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BMW K100 & K75 (83-91) progressive fork springs

FlatRacer BMW K100 & K75 (83-91) progressive fork springs

FlatRacer BMW K100 & K75 (83-91) series fork springs progressive fork springs

This sale consists of:

  • 1 x Pair FlatRacer BMW K100 & K75 (K2v series) progressive fork springs (pair)

This set of springs is designed to fit all BMW K100 & K75 models fitted with either the early Brembo or the later the Fichtel & Sachs 41.3mm forks


  • K100             (09/1983 - 08/1987)
  • K100             (09/1987 - 08/1990)
  • K100LT         (09/1986 - 08/1991)
  • K100RS        (09/1983 - 08/1989)
  • K100RT        (09/1984 - 08/1989)
  • K75              (09/1985 - 08/1988)
  • K75C           (09/1985 - 08/1988)
  • K75 S           (09/1985 - 08/1991)
  • K75 RT         (09/1985 - 08/1991)

IMPORTANT: It will NOT fit the later post 08/1991 K series models fitted with the 41.7mm Marzocchi forks. It will also NOT fit the K75 models introduced after August 1991 (40mm Showa forks).

The FlatRacer BMW K2v Series pair of progressive fork springs are designed for improved handling and ride. The progressive winding means that as the suspension becomes compressed the springs become stronger, offering a more controlled suspension movement.

Their coil design with its rising rate allows to gently absorb small road bumps, greatly contributing for a comfortable ride but as you ride through harsher terrain (pot holes, bumps and other road imperfections), the springs will gradually firm up to provide a very controlled ride. 

Another noticeable advantage over the standard linear springs is the greater control it offers over front end dive when braking, which is very noticeable on a BMW K series with tired springs due to its heavy weight often further compounded by big fairings, panniers, pillion luggage etc.

Heat treated for a long working life and ground ends ensuring a correct and positive fit. Can be fitted either way.

BMW K series forks springs tend to get work fatigue and become inefficient in as little as 3 years of normal riding. This tends to aggravate an already softly sprung front end with its long suspension travel. BMW in fact recommended their replacement every three to five years, depending on usage. 

The result never fails to impress for how much stabler and compliant the front end will feel. 

New oil and seals are also recommended.  Please specify your bike model & year when ordering as there are subtle differences.

Fits all the BMW K100 and K75 models made between 1983 and July 1991 (K100) fitted with the Brembo or Fichtel & Sachs 41.3mm forks. 

Replaces original BMW fork springs: 31421457904  

Similar fork springs'sets available for other models, please check our other listings.


1 - If your forks are fitted with the original alloy or nylon spacers (on top of the springs, usually 15-20mm in height), please re-fit these when replacing the springs. 

2 - When replacing the springs, it is highly recommended that you also change the fork oil. Please check the workshop manual for the correct viscosity for your specific model or contact us for further advice.

Similar progressive springs  will also be available shortly for the later K4v series fitted with the Showa 41.7mm forks (post August 1991) and the K75 models fitted with the Showa 41.0mm forks (post September 1991). Please contact us for more details regarding suitability and fir for your bike and delivery schedule.

Please note that this is a fairly bulky/long item thus the higher shipping costs. We will very gladly combine shipping costs. If interested in any other items, please contact us for a quote or invoice.

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