I asked this question last week, and ive been back to the Dealership today to sit on the Nightster again, there,s not loads of difference but i think the bars fitted to an Iron will make a positive difference. Ive noticed my elbows lock sometimes and it dont feel comfortable sliding around the seat trying to find a more comfortable position..The dealership parts guy tried telling me i need to change all my cables and turn signals ,which seems expensive ,but comparing the Iron and Nightster today i think only the upper brake line needs to be changed and all the other stock items will fit fine..I just hope someone does the swop over before me so i can follow their progress.....

 

Save your self some trouble. Invite a buddy over. Take off you top clamp, hand him the bars with cables still attached. Put the Nightster bar on, attach top clamp and feel it out. If you like it leave em aon and switch over all the controls. If you don't just put your bars back on.

 

its the same part # according to my hd dealer. there are no difference in the iron and nightster bars. the only one thats different is the 883c and the 883 super low but those are chrome

 

Sounds like you need to find a new dealer. They are most definitely different bars as the OP own both sets of bars and has them side by side to compare. When the iron came out they even advertised it as having "new, low profile, drag bars."