Hi Rob,
thanks for the info. 25 inch seems to be the right length - my inner cable has a length of 65,5 cm, the outer shell is slighty shorter.
Actually I did not find the JJ cables website. Speedo cables shown at Feked are longer. Is there any other supplier?
Instead of contacting the cableman I decided to ask a German manufacturer of cables. I've sent the orig. cable to them and will receive an offer during the course of this week.
Meanwhile I got the new cable from the manufacturer www.bowdenzugmanufaktur.de. They charged 75 Euros and reused the fittings for the front wheel and the Smiths speedo.