Both our tandems have 3x9 drivetrains using 2005-era Shimano derailleurs, road front and mountain rear. I use 11-34 cassettes and the triple on our Speedster is 52-39-26. I use the largest 3 or 4 cogs with the 26 chain ring on the steepest climbs. I try to avoid crossing the 52 with the 34 cog, but the chain is just long enough that nothing will break if I do. I have a chain catcher and the low limit screw on the FD is backed all the way out. The shifts all work perfectly. Once the chain drops onto the 26, I just trim the FD slightly to stop the cage from touching the chain. The total range is 6.18 and we use all of it.