Rear derailleur indexing problems

elcani

Hi

I'm having trouble getting my drivetrain smooth when the chain is on the biggest 3 rear cogs.

Bike: GT Avalanche 1.0 Disc
Mech: Shimano Deore LX
Shifters: Deore
Cassette SRAM

Everything is stock and has done less than 300 miles since new.

I've followed a step-by-step video to indexing a rear mech and I'm fairly confident that I understand the principles and processes involved. Everything works perfectly on the smallest 6 rear cogs, but when the chain is on the top 3 rear cogs, the drivetrain 'ticks' and is not smooth. You can see the rear mech 'flicking' backwards and forward, this behaviour being especially noticable when pedalling backwards..

I've spent ages making minute adjustments to the cable tension, but cannot get it to work properly. The problem is present when using all three front rings.

Any ideas or advice greatly appreciated - could it be a stretched chain despite the newness of the bike?

Many thanks in advance

nicklouse

time to clean the cable?

what cog is the front set to?

elcani

Thanks, I'll try cleaning the cable. I was doing the indexing using the middle cog, but the problem is present on all three.

Cheers.

bikaholic

Try adjusting the B tension screw on the RD.

Shift the chain onto the smallest chainring/biggest cog and adjust the screw just enough to eliminate the vibrating or "ticking" movement of the derailleur cage, but not so much as to cause sloppy shifting.

Then, shift the chain onto the biggest chainring/smallest cog and adjust as necessary.

You are looking to get the best compromise between these two adjustment settings.

Maxticate

I've been having near enough the same problem with the same bike although mine has a few more miles on it and is older by the sounds of it.

The chain would skip up and down on the innermost cogs under load when on the middle chainring front. I adjusted the Hi Lo screws so they were ok. I'm going to try the B screw setting now.

Thanks for the suggestion.

Max

allthegearnoidea

the way i have always set mine up is to undo the cable from its clamp on the mech, wind in all adjusters so they are at the most minimal and then take up the slack cable ont he mech, then just setting the stops on the mech,

i'm not saying it is the way to do it but its the way i have done in the past and had no issues with gears through!

Matt 24k

Timmo's method works for me every time on every bike. This assumes that the cables are clean and lubed and that there are no tight chain links or damage to the cassette, mech, or the mech hanger.

bungalistic

I use this as a guide and it works just fine:
http://www.nsmb.com/2923-adjust-your-rear-derailleur/

elcani

Thanks for all the advice.

The method I used was the same as Timmo, so I have a feeling the B screw might need a tweak and/or the cable needs cleaning.

I've been careful to keep the drivetrain clean and lubed until now, but I'll do a thorough check for stuck chain links. I'm fairly sure the mech hanger, mech and cassette are undamaged.

Cheers

rhyko7

my ride starts with the gears working perfectly
by the end they are all over the place

i dont think the LX derailer is any good (chews cables up on a monthly basis, due to bad routing through into cable clamp) , i may try running the outer right the way to the mech or getting cable seals, because a lot of the problem is from cable resistance due to grime getting into the outer.

p.s put your bike upside down, check your derailer is inline and that parts of your chain have not twisted, make sure drop out hanger and derailer fixtures are tight!

Johnny Napalm

This works for me...

http://www.youtube.com/watch?v=SkzvfCaIbyQ