How to adjust cable tension on Dura-Ace 7700 shifter I have a Giant Defy 3 which came with Shimano Sora groupset. A friend gave me some older Dura Ace 7700 components in good condition so I'm upgrading most of the components including brakes, shifters, and derailleurs. But the barrel adjusters are different so I'm not sure what the best option is here.

The Sora shifters are threaded for a barrel adjuster but the Dura Ace are not. Instead, my friend's Dean frame has threaded bumps brazed onto the downtube, and the adjusters thread into there. I have never seen this style before. My bike has a regular holder on the downtube for the shifter housing but it's not threaded.
Jagwire along with others manufacture in-line barrel adjusters. As the name implies they are installed between two sections of outer cable housing. They are generally installed 6-10 inches from where the cable exits the shifter. You want it close enough to the bars to be able to make adjustments while riding.