john said:Nick Dobb said:"Nick Dobb" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:"Robert" <[email hidden]> wrote in message
news:[email hidden]...
>Nick Dobb wrote:
>
>>By marking up the cable in each of the positions, I have confirmed that
>>the cable is ending up in a different position by as much as 1-2mm when
>>in what should be the same index position, depending on whether I've
>>shifted up or down
>
I then had a brainwave and undid the cable and completely removed it from
all the outers, and applying manual tension to the cable repeated my
mark-up-the-cable-in-each-of the-index-positions where the cable exits the
shifter. This has demonstrated that the shifter is shifting the cable (at
the point of exit from the shifter) to near enough exactly the same
position in each index position, regardless of whether shifting up or
down.
I therefore diagnose a problem with the cable sticking in the outers, and
will replace them all (and the cable) and report back.
Grrrr. This is doing my head in. I now have new cables and outers from my
LBS installed on the bike (actually the LBS isn't all that L at all but
never mind). I know (because I've checked) that with the cable disattached
from the derailleur and steady manual tension applied, the cable is getting
pulled to pretty much exactly the same position in each index gear,
regardless of whether shifting up or down. But then I attach the cable to
the derailleur and set it up, and the problem persists. If I set it so it
shifts sweetly going all the way from high to low, then it's about a whole
gear out going back the other way. Or vice versa. Nothing has changed. The
derailleur mech is brand new. Everything's lubed up with light oil. I've
unscrewed both end stops all the way out so they're not getting hit up
against and are not part of the equation at all.
Help!!!!
One more thing I can think of:
Are you certain that the end of the cable is attached to the correct
side of the "hold down screw" (for lack of a better term)? It's easy to
get it on the wrong side. There's a 'V' groove where it's supposed to
be. The 'V' groove is a little hard to see under the top plate.
Hope this helps, John
Hi again,
If the LBS is charging you parts and labour to install new cable and
outer, then the price should include the whole setup actually working,
once they've done the repair. If the problem is in the cables, then they
should bear the responsibility of an incorrectly done fix. If the
problem is elsewhere, then they should have determined this before
replacing the cable and outers, otherwise they are simply experimenting,
using your time and money.
Also check that there are proper ferrules installed on the cable outers
(thin metal sockets covering the ends of the cables) which keeps the
ends of the cable outers more rigid and less likely to grab on the cables.
Another idea - look at how the cable runs under the bottom bracket,
probably via a plastic guide. Make sure that there are no rough edges there.
Finally, do a check by unscrewing the bolt with which the cable attaches
to the derailleur, hold the end of the cable taut in your left hand
(pulling towards the front of the bike), and shift upwards/downwards
using your right hand. Confirm, this way, that there is no undue
friction anywhere in the system. If the cable slides easily, test
another shifter and see if the problem persists.
BTW I don't believe that the cable will have been routed on the wrong
side of the stop bolt, since you have already said that it shifts
properly, going from small cogs to large cogs.
/Robert
