Stiff Shifting Levers I was helping a friend build a bike from used ultegra 6700 components, and for some reason the shifting levers feel really stiff or difficult to shift, particularly when increasing in cable tension (down shifting the rear or up shifting the front). 

I don't feel any resistance in shifting when the cables are disconnected from the derailleurs. Not sure if this means the issue is possibly caused by something other than the shifters, or if the shifters only display the issue when tensioned.

Any thoughts?
The resistance is likely caused by friction in the cables/housing or something to do with routing. It's a bit suspicious that it's happening in both shifters though.

To track the source of the resistance down, start by detaching the derailleur, pull the cable put some tension on it and work the shifter to test for stiffness. Work towards the shifter taking the cable out of housing sections and retesting at each step.

If the shifters them are binding up under tension, you should be able to replicate that when you have the cable out of all sections of housing, emerging directly from the shifter.