Shimano 105 skips second position on way down
 

I recently bought a used bike with 105 STI shifters. I'm not sure the left shifter is working correctly. It's a 9 speed triple, ultegra derailleurs.

The left shifter has four positions. As I understand it, it should be adjusted such that 1 is the inside position and 4 is the outside position, 2 and 3 should be slightly inside and slightly outside of the middle chaingring respectively.

Problem is, when I'm in 3 (middle, outside) and want to trim to 2 (middle, inside), there is no single click click available. I can only release all the way to 1. I'm pretty confident that cable tension and both stops are set correctly. All four positions work nicely on the way up the chaingrings.

Question is, should I be able to click from 3 to 2 when properly adjusted? That is, is the shifter broken?

I've tried to overcome this problem by setting 1 and 2 as inside/outside positions on the inside chain-ring, 3 in the middle, and 4 on the big chainring. This way a shift from 3 to 1 puts me in the small chainring and if it's rubbing (because I'm cross-chained (which, of course, I shouldn't be)) I can just trim to 2. Unfortunately, even with the stops properly adjusted, set up this way position 4 rubs when in the smallest gear in back (rubbing on the outside of the chain). If I tighten the cable even a little, it won't shift from 4 to 3. Also, without a trim, I don't have the range I'd like in my middle chainring (this is the biggest issue).

I also read somewhere that 3 and 4 should be set up as inside/outside on the large chainring?!!? Seems people are all over the place on this. Even that doesn't work for me. Set up this way, shifting from 3 (which would be inside position, large chainring), it skips 2, jumping directly to my small chainring.

Thoughts? Again, could it be that the shifter is broken?

Figured it out.
 

Though nothing on the interwebs told me so, turns out there are five positions on my shifters (105 STIs). I had the cable too tight (and probably the high stop screweed too far in). I'm still dialing it in, but now I have 1 on the small chainring (resting on the stop and the cable pretty loose), 2 is a small click in (mostly taking the slack out of the cable and pushing the derailer a little way), 3 slightly inside the middle chainring, 4 slightly outside the middle chainring, and 5 sitting on the large chainring. Seems I only have about 3 gears in the rear cassette when in the large front chainring before it starts rubbing.

I believe 2 is actually some sort of trim for the small chainring and that the shifter is "supposed" to skip it when shifting from 3 to 1.

You've got the concept right. With Shimano triple setups I think of the clickstops (detents) this way: 4 primary positions plus an additional trim position from the extreme left side. When adjusting the cable I've found that usually it's best to have no slack in the cable when in the extreme left position with all of the cable out of the shifter. I think the problem you previously had with the shifter jumping from the 3rd position to the 1st position was from too much cable tension. Some setups seem to work best with a small amount of cable tension when in the lowest (first) position. YMMV. If you are able to use all of the normal gear combinations with no chainrub on the derailleur then you are good to go!

Al