You don't want brifters on a trekking bar PERIOD. I'd go with Gripshift Attack shifters if you're going to put the shifters at the ends of the bar, but not many folks around here like Gripshifts, are you one?. If you want to put them at the "front" of the bar I'd probably go with fietsbob's suggestion. Or even get some old DX/XT/XC/XCPro thumbshifters and run them in friction mode.