Derailleur not shifting evenly?

[Jamie96]

Hi everyone, new to the forum and would like some help before i start cycling.

I have a gt avalanche 2.0 with shimano deore shifters and a new shimano deore RD. I've been trying to set up the RD but it seems to shift by 1.5 sprockets towards the lower gears e.g 8-7-6-5-4-2.5-1-1 with the final shift being really tight and barely doing anything, higher gears are fine. Installed a new cable and housing as the old one was worn but still does it. The derailleur and hanger are new so aren't bent.

Also around the front of the frame makes a sort of grinding noise when i move the handlebars, could this be the headset bearings? if so how do I go about finding what replacement parts to use?

Tried to give enough info. any help would be appreciated

 

[themosquitoking]

Did you index the derailleur after replacing the cable?

 

[raleighnut]

You don't mention how many front rings you have but it sounds to me that you may be "crossing the chain"
big ring 8-4
middle ring 6-2
inner ring 4-1
or
big ring 8-3
inner ring 5-1
As for the headset it sounds like the bearing spacer has gone. These are easy to change or try doing my trick and using the old loose bearing method.

 

[Jamie96]

I indexed it before however it seems to move when i put the cable in, do you think this could be the problem?

 

[Jamie96]

These problems are without the chain on raleighnut, would it be easier if i had the chain on?

 

[Cubist]

Too much tension in the cable, and a rear mech that needs adjusting/aligning with the cassette.

Slacken off the cable at the mech by undoing the hex nut holding it to the mech. Check the cable runs properly through the clamp. If you get it routed wrongly it will give the symptoms you describe. Check Shimano tech docs for helpful diagrams. Even clamping it the wrong side of the clamp bolt will be enough!

Do all of the following with the chain on the middle ring.

Next, with the tension out of the cable, the mech will drop to the bottom of the cassette. Check that you have the b limit screw adjusted so that there is a minimum clearance of 5 or 6 mm between the top of the jockey wheel and the smallest cog. The b screw is at the back of the mech and winds the cage up,or down to adjust the fit. Make sure the cage and jockeys line up exactly with the smallest cog. If not, wind the mech in or out using the limit adjust screws. Once it's lined up, fire the shifter off so that it is at the lowest setting, and wind the barrel adjuster all the way in, then out a couple of turns. Now pull the cable taut through the mech clamp with pliers and tighten the clamp bolt. This way you takes the slack up in the cable, but not adding much tension.

Now the fun bit. Shift to the second cog with the thumb lever. If it moves up smoothly and quietly then that's the first bit over. If not, then you need to add cable tension via the barrel adjuster a quarter turn at a time until it does. That's half the battle. Now, shift up another cog, and if this goes smoothly, shift back down. The chain should drop instantaneously. If it hesitates, back off the barrel adjuster a quarter turn and try again. I was once told that once you are able to shift to second, add cable tension until the mech wants to shift up on its own, then back it off again until it only just doesn't. thats fine on some cassettes, but gets messy on wide range cassettes. Once it shifts smoothly from one to two, two to three and back down smoothly, shift all the way to the biggest cog. Use the limit screw to make sure the jockey is exactly in line with the cog, and check the jockey to cog clearance again. You may need too increase clearance if its a wide range cassette, otherwise the chain will foul on the cassette when you shift to the biggest cog.

Now, shift down one, and check to see if the chain drops instantaneously. If not, make small adjustments on cable tension until it shifts between the biggest two smoothly and cleanly. It should do now. Check it still runs up and down the cassette smoothly. It's a bit trial and error, but if everything is properly lined up this should be it.

 

[raleighnut]

All adjustments should be done with the chain on except the basic settings of the upper and lower limit stops I just assumed you knew, sorry bout that

 

[Cubist]

Are you using an 8 speed compatible derailleur and shifters?

 

[Jamie96]

Yeah, using shimano 8 spd shifters and derailleur

I thought the chain would need to be on for fine tuning but this problem seemed abit odd even without the chain on

 

[RecordAceFromNew]

Chance is you are clamping the cable on wrong on the mech. If you look at section 2 here you will see that it is quite specific how it should be done, so worth checking.

 

[Jamie96]

Thanks for the help, turns out the cable was clamped on the wrong side of the mech

 

[Kookas]

Also around the front of the frame makes a sort of grinding noise when i move the handlebars, could this be the headset bearings? if so how do I go about finding what replacement parts to use?

My Triban did that, thought it was a brake cable though.

 

[HLaB]

Index the highest two gears any thing else is cable snag. This is a good video for explaining