Originally Posted by redscarf
Also, depending on how taught I made the cable before tightening it at the rear derailleur, my STI shifter clicks only about six or seven times when shifting, even though it's indexed for ten. I feel like I've tried everything. Does anyone have any advice? Should I just go to my local bike shop and have them do it for me?
Sorry, I should have read your OP more carefully. There are a couple of things that can cause this.
If your STI shifter is only clicking six or seven times, then you probably did not completely upshift it (with the small lever) before you pulled the slack out of the cable. Push repeatedly on the small lever until it stops clicking. This should set you up for the highest gear (the smallest rear cog).
Now, before you take the slack out of the cable and lock it down, pull the brake lever and look inside the STI assy and make sure the cable anchor head is seated correctly in the STI. If it is, now you are ready to pull the slack out and lock down the cable.
You should be good to go at this point. If a downshift click with the big lever does not give a corresponding shift up to the next bigger cog, then turn the barrel adjuster a full turn. Repeat until you get a full shift and then fine tune the barrel adjuster for the smoothest shift.