If the bike should need a new chain and rear cluster you would be looking at around $50 USD. But with what you describe there are steps you must do first to help with your diagnosis. You need to check the cable and housing for binding, you need to check the derailluer alignment, The rear wheel must be trued and the axle must be not be loose either, nor the bottom bracket. Then the gears must be set properly. Do you have a derailluer alignment tool ? Do you know how to set the gears properly? If need be can you size and replace the chain correctly? do you have the tools to remove the rear cluster? If not, do you have access to a local bike co op to help?
I would also take a close look at the derailluer to make sure it moves freely and the jockey wheels are not worn.
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
Typically, this is from crosschain. On 1x setups you can get a clunking sound now and again. Perfectly okay and happens even if your indexing is perfect. Sometimes tightening the chain helps.
You should first check your indexing on your rear derailleur. Shift down into the smallest cog. Undo the cable. Dial the barrel adjuster all the way in (screw it in all the way). Pull the cable just lightly to remove slack and re-fix the bolt. If you put too much pretension on the cable during this step, you will mess up your indexing. Once that's done, slowly begin to dial the barrel adjuster out and try to shift up. If it doesn't shift, click it back down and dial the adjuster out some more. Repeat this until it begins to ascend and descend perfectly. Check your high limit screw and make sure it's screwed in just lightly to touch the anchor. If necessary, dial it out all the way, then peek inside and dial it in until the screw begins to touch and push against the anchor just lightly.
Once indexing is fixed if possible, and the chain still skips, you either need to replace your chain and/or you need to replace your rear derailleur. The reason likeliest being that the hangar is bent and this is causing cross-chain and indexing problems.
On a farther note, you could also need a rear derailleur hangar alignment. This isn't the rear derailleur, but the place where it bolts into the frame (if you have that kind of style RD). You'll need to take it to your local bike shop for this.
You should also clean the gunk out of your cassette and rear derailleur.
11-18-2022, 10:37 AM
Yup that is done for. You can try and get away with adjusting the derailer and tightening the chain up a bit. If that doesn't work, replacing the chain won't work either. If you are going to keep the bike for a few more years, I would replace the whole drivetrain if you have the money. Switch to a 1X 12. If you have a 3X8, then it's time to trade it in.