SRAM X.xxx shifters are incompatible with Shimano derailleurs. As you've found, the SRAM shifters pull more cable than Shimano derailleurs can use.

You can use Shimano "flat-bar" shifters, but that may mean you will need a different front derailleur. (See my earlier reply here: http://www.bikeforums.net/showthread...my-derailleurs )

Would you object to friction shifters? They're generally cheaper, and learning to shift them is no big deal: http://harriscyclery.net/product/var...fters-2741.htm