Originally Posted by KCT1986

Don't know what Zukka is. Are the shifters the Shimano Tourneys?

If they are Shimano Tourneys, they may work for 6 speed (5.5mm) spacing by using an alternate routing method. See Sheldon Brown's article (sticky in Bike Mechanic forum) about Dura Ace . You want to try the position B to emulate a Shimano RD-7400. If you have a common Shimano compatible SIS road RD up through 10 speed (non Tiagra RD-4700), it should work.