I have been working on a bike and simply cannot get the gears tuned. I have replaced the hanger and the rear derailleur, new cable and housings. The gears click smoothly from the smallest cog to the second but after that it’s all over the place and on the 5th click is up on the 7th cog and the cable is super tight. I have been gently tweaking the barrel adjuster but I can’t get it to flow. Any ideas?

Make sure the mech hanger is straight, not bent L/R or forwards/backwards.

Make sure each section of the outer is in the cable stop properly and the cable stops are all fine and seated in the cable guides properly. Not squashed or bent or missing.

Also, did you actually start with the gear selector in the correct position. Its easy to be one click wrong.

Have you changed the chain or anything else?

I’ll ask the daft question, is the shifter and cassette definitely the same ‘speed’

Assume the shifters and mech are for the same speeds and bike type?

check the cassette for bent teeth, check the free hub body is not wobbling as slight movement will be amplified when moving up the cassette, check the chain for stiff links, make sure the cable is correctly fitted to the rear mech pinch bolt. You may need to fiddle with the B-tension screw

It’s a new chain, so no seized links. I have checked that the cable is in the right place in the pinch bolt. Shifter and cassette definitely the same speed.

Cable off and do the limits from scratch.
Reset cable and go from there also get the hanger/dropout checked if you can.
Also is the mech straight?

Sorry if this seems a stupid suggestion but did you set two screws that limit the throw of the rear mech first?

Disconnect everything and start from scratch! Check that the new run of outer cable from the last stop on the chainstay to the rear derailleur is not too tight a curve, this caught me out a few times. Make sure the new outers are all sitting happily in the stops on the frame and that any new end cuts are nice and clean.
Ensure the H/L limit stops are set correct when the cable is disconnected, use your hand to move the derailleur through its range. Reset the barrel adjuster on the shifter, and check the shifter is pulling cable through the outers freely. Reattach everything and try again! Good luck…

Apologies if this is insulting your intelligence but you haven’t mixed SRAM mech with shimano shifter or vice versa have you?

Had 3 of those in the shop in the last week with customers adamant it should work…

Speed?
11 speed needs PLENTY of cable between the last stop and the mech.

APF

If Shimano check Cable routing!!!! The pull ratio changes if you don’t route the cable the right way. It is not obvious and confuses people when it happens…

Br
JeZ

This is how single speeders start 🙂

It’s a new chain, so no seized links.

Is it the right length?

Start at the he beginning.

1: Check that ALL parts are compatible.
2: Then check the mech hanger is straight. A new one is no guarantee that it’s straight.
3: Check that the cassette is mounted and tightened correctly.
4: Check each part for damage / wear.
5: Jockey wheels?
6: Cable routing?
7: Hi / lo mech stops?
8: Pinch bolt cable routing?

Still no good?

Singlespeed.

*Yes chainline is important.

Just a thought but check the gear cable end ferrule is fully seated in the gear shifter, I once had a problem with a ferrule that had rough edges which stopped it fully seating in the shifter, a quick rub with emery paper sorted it.

Then check the mech hanger is straight. A new one is no guarantee that it’s straight.

This as a starting point. It’s a cheap tool and easy to do.