Rear mech adjustment issue...

[andyoxon]

Probably something basic.  I don't seem to be able shift down one cog on cassette (10spd), from largest (32) with one click of the shifter, which ever front chainring I'm in.  Takes two shifter clicks.  I've done H & L limits, re-attached cable (holding taut only) with barrel adjusters closed etc.   Chain shifts up to 32t fine, but then does not move down one cog with one click. 

Any ideas?

edit.  Ok, I think it was that I had actually pulled the cable too tight before clamping it.

[robgul]

Is the cable outer sound with ferrules at all of the ends?     I had a similar issue in the shop yesterday and the problem was the outer's longitudinal wires slowly pulling through a ferrule with each shift with the effect of changing the length of the inner cable pull.

Rob

[rogerzilla]

Also eyeball the mech from the rear.  Is it visually parallel to the wheel rim?  Try and ignore the seatstays, as they confuse the eye.  If it's not perfectly vertical, your mech hanger is bent.  You can straighten an integrated steel one if you know what you're doing (you'll need a long steel rule - check for vertical alignment and twist and be careful not to over-bend it so you have to bend it back again), or replace a sacrificial bolt-on hanger.

[Torslanda]

Another one that's a bit odd is the mech limit screw. Don't know exactly why but if the last click pulls the mech hard against the limit stop it won't release. If this is the case - and the hanger is straight etc. - try backing off the limit screw a quarter turn.

[andyoxon]

Thanks.  I 've had some issues with RD on another bike, and couldn't work out why the RD was always over too far (out of alignment) on the third from largest rear cog (with all the barrel adjusters closed etc), and it looks like this was also not leaving the cable 'loose' enough while clamping...