We replaced our drivetrain early on with Tiagra 3x9 shifters, 105 front and Deore LX rear derailleurs. I didn't care much for the Sora stuff that came on it. I kinda like the Tiagra shifters on the tandem since they have the indicators on the hoods showing what gear you're in. It's harder to glance down and look when the derailleurs are so far behind you.