santiagobike

I recently bought a 2009 Specialized Bicycle wiht Shimano 105 5600 components. The right lever (ST-5600) is 10 speed, but it will only make 8 clicks, which effectively makes it a 9 speed lever.
There was no ST-5600 for 9 speed, which leads me to believe it is a mechanical issue.

What could be going on? The 9 shifts that do engage do so smoothly and without any complications.

Iride01 

Have you grabbed the bare cable and pulled it out as you counted the clicks? But really the first thing I'd check on is if the cable end is frayed up in the shifter. Messing around with it before determining that might get the cable so frayed that it will make you cuss trying to get it out.

You really have to pull the cable out of the shifter a few inches to be able to inspect if for fraying. That means you'll have to release the cable from the pinch bolt on the DR.

If it's not that, then hold on the the bare cable end and keep some tension on it as you click the shifter both ways till it stops feeding in or out. If you aren't getting the clicks then, you'll know what to replace or maybe attempt to fix.

santiagobike

The cable is not frayed, since it is a new one. It was serviced one week ago.I still get only 8 clicks.

dsbrantjr

Did you get 9 clicks before you serviced the bike? Check the cable travel with the cable disconnected from the derailleur as suggested by Iride01 (after checking for fraying). You may not have had both the derailleur and shifter in the highest cog/highest gear (cable completely paid out) positions when you reinstalled the cable and the last click is being inhibited by the derailleur stop.

Iride01 

If you didn't remove the cable from the pinch bolt of the DR then it might be that the cable is being held too short by the DR. So when you shift you don't have enough movement left in the DR to let the shifter make that last click.

If you don't get the 9 clicks and feel the cable moving a measured amount each time, then it likely is a bad shifter. Shimano shifter cable right? Not Campy or brake cable?

It could also be that someone mucked around with one or both of the limit screws and that is keeping the DR from moving far enough to allow that next click. Don't be willy nilly fooling with the limit screws though. Check for the cable being held short first.

Shimano had several different versions of the shifters in the 5600 group. Don't know if the differences are material to any servicing or adjustment. But you can find the exact version number on the shifter body if you pull up the rubber hood from the bottom... usually. Then pick one of these SI's and study it. Though they can be sparse for explaining things, there is just enough info usually to get you on the right track.

https://si.shimano.com/#/en/search/Keyword?name=st-560