Can I replace APEX front derailler with Shimano?
 

Sorry - searched, couldn't find the answer.

Wife's bike has Apex shifters, front and rear deraillers -- front just isn't working well. Will a shimano FD work with APEX shifters?

Thanks.

Yes. The ratios are the same for the front for both Shimano and SRAM. So you can definitely do it. I ran an Ultegra front derailleur with Apex shifters for about 6 months, no problems. If you don't want to go with an Ultegra, you could also use 105 or Tiagra.