Good morning, I've done some searches but haven't quite found what I think I need to solve my problem...

My Kona Jake has a 3x8 drivetrain, with Sora shifters and F/D, and Tiagra R/D. There are about 7,000 miles on the shifters.
Got the cables replaced at the LBS about 400 miles ago and the shifting has been great, until today.

My last ride ended with me in the big chainring, and this morning when I went to shift to the middle for my ride to work, nothing happened with the F/D, rather the cable just went slack, and slacker still as I "shifted" the shifters I guess into the small ring position. At first I thought maybe the cable has snapped or slipped, but it's secured at both ends, and I can get it to tighten back up by moving the shift lever through its range of motions to the big ring position.

I'm comfortable adjusting my R/D, but the front has always given me fits, so am wondering if anyone has any advice as to steps I should try, or to just take it to the shop?

Thanks in advance.

FD is easy, you can do it! www.parktool.com has all the info and some nice pics.

First thing to do in these situations is to absolutely bathe the shifter in WD-40 and lube the cables well too, see if that fixes it.

It sounds to me like the shifter is doing its thing correctly, because it's creating slack in the cable when going from highest to lowest indices. The problem sounds like that cable isn't being taken up somewhere. Could be where shifter meets cable, could be the housing, could be the FD, heck it could be the bottom-bracket cable guide if your bike routes them that way.

This should be relatively easy to diagnose, just find where the slack is created and how far back it goes.

The front derailleur should have gone down to the small ring with a slack cable unless something is jammed.

I'd take a look at the derailleur before I went crazy on the shifters.

+1
Where did you see the slack cable. If it was down toward the derailleur, the derailleur is not functioning correctly. See if the derailleur spring is still in place and not broken. If you're lucky you may be able to restore shifting by cleaning and lubricating the front derailleur.

Al

thanks all for the advice.
turns out one of the nubs that the spring ends pushed up against had snapped off...