The 3-arm TA isn't a Cyclotouriste, which may or may not be significant WRT axle length. With a Cyclotouriste (Pro 5 vis), I'm using a 373 for a triple, and the chainline is as close to perfect for a 7 speed freewheel as I can discern. Not being an engineer, I'm limited to visually lining the middle chainwheel up with the middle cog The 344 was perfect for a double with both an Ultra-6 and 121 mm OLD and 7-speed and a 126 mm OLD.