Rear Derailleur question

tunney

Normally I can re-index a rear derailleur in a few minutes. This morning I spent 3.5 hours trying to get my 10spd Ultegra 6600 (or 6700) rear mech right. I just couldn't get it. I could get it perfect in either up or down but not both.

When going up the way perfect it would either not go down one or hesitate too much. It was easier to get it right going up than down.

I suspect that maybe the spring in the 5-6 year old derailleur is gone or going. Can this happen? Are these the symptoms?

petethedrummer

I do it upways.

Is there play where your derailler attaches to the hanger?

tunney

petethedrummer wrote: »

I do it upways.

Is there play where your derailler attaches to the hanger?

No play, chain length good, B-screw fine.

Chips Lovell

A bent hanger, even one slightly out of alignment, will often create problems shifting into smaller cogs, particularly near the bottom of the cassette.

Paul Kiernan

I had the same problem recently. I changed the cable and it's now (almost) perfect.

Now, I can't see why an old cable, even if stretched, won't index properly, unless it stretches more under increased tension.

And when I say it's almost perfect, it seems to be changing fine, both up and down, but in 2 it's rubbing slightly against the 1 cog (i.e. cable is too tight) and in 9 it's rubbing slightly against the 10 cog (cable too loose!).

tunney

Vladimir Kurtains wrote: »

A bent hanger, even one slightly out of alignment, will often create problems shifting into smaller cogs, particularly near the bottom of the cassette.

Thanks, but I never mentioned anything like that.

tunney

Paul Kiernan wrote: »

I had the same problem recently. I changed the cable and it's now (almost) perfect.

Now, I can't see why an old cable, even if stretched, won't index properly, unless it stretches more under increased tension.

And when I say it's almost perfect, it seems to be changing fine, both up and down, but in 2 it's rubbing slightly against the 1 cog (i.e. cable is too tight) and in 9 it's rubbing slightly against the 10 cog (cable too loose!).

Cheers, changed the front cable but not the rear. Could be it.

Hmmzis

Check cables and cable housings. Any grit or dirt near the exposed sections of cable? Take off one of the housing sections near the derailler and check for any dirt build-up or rusty sections of the cable.

If there is added frictions on the cables it can cause the shifting to be hesitant at first and adjustments tricky to impossible. The spring can only pull so much. More than that and there will be issues.

I had a similar issue on my MTB and after changing the cables and cable housings the issue disappeared. It's shifting as new again.

ashleey

Look closely though, is the derailleur vertical? If it is not it won't shift correctly. That is what Vladimir means. It might work smoothly changing down but not up or vice versa. It's surprisingly easy to bend a hanger as they are designed to be replaceable to save the derailleur from getting mangled.

tunney

ashleey wrote: »

Look closely though, is the derailleur vertical? If it is not it won't shift correctly. That is what Vladimir means. It might work smoothly changing down but not up or vice versa. It's surprisingly easy to bend a hanger as they are designed to be replaceable to save the derailleur from getting mangled.

Will double check but did check this morning and it did appear to be vertical.

07Lapierre

A worn Chain will make adjustment more difficult. if the cable is old/worn, replace it too.

D20903

Your hanger needs to be re-aligned.

instinct

Could never get mine 100% perfect. Sometimes it felt fine but always ended up needing slight adjustment.

Left it in for a tune up and sure enough, hanger was slightly bent. Ill be more careful putting the bike in the rack at work.

tomasrojo

I've found before that a new gear cable was needed.

I've assumed that it's like old guitar strings; they just won't settle on the correct pitch when they're very old.

victorcarrera

Release the cable, pull it out of the shifter and inspect that end to make sure none of the strands are broken. This is where the bend and wear is greatest.
Next check that there is free movement in the short outer cable that links to the rear mech. This also has a sharp bend and is more exposed to wheel spray.
Sometimes a combination of excessive lateral play in a worn chain, pulley bearings and caked up rear mech spring can cause it.
Slow upshifting usually means a sticky cable.

irishmotorist

I'd +1 a new cable. I know I need a new cable when I can't get the derailleur perfect on either an up or a down. It is usually on the way out.

tunney

07Lapierre wrote: »

A worn Chain will make adjustment more difficult. if the cable is old/worn, replace it too.

Cheers - chain tool says its good though.

D20903 wrote: »

Your hanger needs to be re-aligned.

Nope. All good there.

tomasrojo wrote: »

I've found before that a new gear cable was needed.

I've assumed that it's like old guitar strings; they just won't settle on the correct pitch when they're very old.

Yeah - cannot remember how long ago it was since I changed the rear cable. Did the rest of them recently but I think I ran out of outers. Got more cheapo ones at lunch and ordered from Jagwire to do it properly next week.

irishmotorist wrote: »

I'd +1 a new cable. I know I need a new cable when I can't get the derailleur perfect on either an up or a down. It is usually on the way out.

Yeah silly, cannot believe I spent 3 hours at it and didn't change the cable. Idiocy.

tunney

New cable outer and inner sorted it.

Cheers all