Yes, with some qualifications. 

The extensions are industry-standard 22.2mm diameter that will fit most standard bar-end type shifters designed for aerobars, however, because the aerobars are quick-release, we do not recommend the use of standard cable-actuated gear shifters, since they would effectively tie the aerobar to the bike and defeat the quick-release functionality. 

If your bike has electronic shifting (either Shimano Di2 or SRAM eTAP), then you can usually unplug the extension-mounted shifter from the junction box when you remove the aerobar, which is a great option.