If you do have the indexed shifters that Slash referred to...they might be able to be switched between index and friction function. Look on the side of the shift level for the rear derailleur. If so...I think you'll be much happier using them in friction mode when the shift index/gear count don't match. (Edited to add...I guess it's the screw slot and not the thumb nut bail that indicates the setting...because that bike is most definately using SIS and not friction.)
Dan
Last edited by _ForceD_; 11-25-17 at 09:26 AM.