numpty gear question, not changing down stis

My STI and cables are around 6 months old, around 500 miles.

I can change up the rear cassette, (i.e larger cogs) but going down to the smaller ones is rubbish. They dont go down one at a time and I can change and then after a few pedals it then changes.

I have turned the cable adjuster clockwise and its as tight as it can go.

Other than a new cable, what am I doing wrong?

cable too tight, look at a video on youtube, you are doing it wrong.

https://www.youtube.com/watch?v=SkzvfCaIbyQ&feature=youtu.be

cheers

The other causes are bend in your outer cables that are too tight or other causes of excess friction.

To set up you gears.
1) drop in the smallest cog
2) undo the anchor bolt and ensure your shifter has no clicks to go.
3) Ensure the the top jockey wheel is the middle of the smallest. Ajudt the limit screw if it isn't
4) pull the cable taught and anchor
5) use the shifter to shift up one gear and down shift
6) if 5) does not happen then use the barrel adjuster. Turning it out adds tension and will help it shift up. Turning releases cable tensions and aids the down shift.
Once you have it going the first two cogs cleanly the others will be right too. You could be done in two minutes.

thanks, have done it, but cant really test, so will see tomorrow morning - works a treat thanks