I feel bad asking this question because I've been doing bicycle maintenance for over 20 years and this seems like a noob question. I was unable to find a Shimano manual to answer this question. I just bought a Norco Threshold CX bike with Shimano Ultegra SL-RS685 brake/shift levers. I want to adjust the cable length for the front derailleur to fine-tune the derailleur position. The cable is routed inside the frame and there is no barrel adjuster to be found anywhere. I looked under the brake hood and did not see anything that appeared to be involved in adjusting the cable length.
Obviously I could adjust the cable length at the derailleur, by loosening the bolt, moving the cable a tiny bit, and tightening the bolt again. But it seems difficult to do fine adjustment that way.
In case you're wondering why I'm adjusting the derailleur on a brand new bike: The front derailleur wasn't shifting properly because the rear fender (installed by bike store) interfered with it. Before I figured that out, I thought the cable length needed adjusting, and I couldn't figure out how to do it. Techically I can leave the cable alone for now, but eventually it will need adjusting and I would like to know how to do that.