davitom

I have recently had the same problem. Tried everything, new shifter, chain, even converted it back to a single speed but wanted an eight spd hardtail. Seems my problem is a loose/ worn derailleur cage. Noticed the cage was angled and it would move side to side without the main body moving. So whenever I was putting any torque on the chain the cage was flexing and causing the shifting. Don't know if it can be tightened or if a new derailleur is in the cards.

NiMO189

As operator says, there is no way that it is "too narrow of a chain." The internal diameter is the same for all multi-speed chains, 3/32". The difference between a "5-speed" chain, and a "10-speed" model is the width of the pins and outer plates. Thus, you can always use a chain that is marketed for a higher number of speeds.
Since you said that you have friction shifters, I would say that your issues are with either the derailleur, or the cable and housing. If the RD cable and housing are stock, it is possible that the cable is getting caught up inside and not allowing the derailleur to move as much as the shifter. If this is not the case I would look at the RD itself. If you cannot diagnose the problem by looking at it, try a different derailleur and see if that makes any difference.
Possible issues to look for: Does the derailleur have play side to side? Too much play will allow the chain tension to pull the derailleur away from the selected sprocket. How is the chain wrap? This can be modified by adjusting what Shimano calls the "B Tension" screw. A quick search will give you more info if you need it. Is the derailleur or hangar bent? This will definitely affect shifting performance and accuracy. If the cage doesn't look straight up and down, something is bent. As I said before, friction in the cable and housing could give you problems. Are there any kinks in the housing? Visible corrosion?
Good luck to you, hope you get it working well!

NiMO189

Also, since it is a new chain, make sure that there are no pinched (aka stiff) links. Turn the cranks backwards and check to see if there are any links in particular that skip. If you find any try to move them back and forth to make sure the move freely. On a new chain this could be fixed easily.

Bearonabike

Checked RD Hangar - it's good
Checked friction shift tension - seemed good but tightened it a bit anyway
The cable does not run under the BB. I have a bit of teflon tubing installed at the elbow where it bends toward the RD. Put some lanolin lube there.
No twisted or stiff links
RD wrap was adjusted to increase the chain's engagement area from 80 degrees to a full 90 degrees on the freewheel. I get the full 9i0 degrees for all gears.
RD had no side to side play and showed almost no case wear. The previous owner said itr saw little use since he bought it new and I believe that given the mechanical condition.

Between rain storms, I rode around the block. No skipping so far.

Thanks for all the help!

bigvegan

Have you tried adjusting the barrel screw on the rear derailleur? That or the derailleur alignment might be the issue.

davebarnes

I suddenly had a chain skipping problem when under load. And, then it started to occur frequently.
The threads here helped me solve the problem: stiff link. Run the chain backwards over the smallest rear cog and there it was.

Of course, before I did that, I wasted time with:
1. Removing front crank and making sure the crank and rings were flat and true.
2. Replacing the freewheel.
3. Greasing the derailleur cables.
4. Adjusting and tightening multiple axles.

cny-bikeman

One would only suspect a stiff link if the problem occurs less than once per chain revolution (chain>100 links, chainring<50 links). Slightly stiff links can show up under light pressure as well, but usually as noise (as they pass through the pulley cage) rather than skipping.

El Aurens

Is it maybe ONLY in HIGH gear and none of the others?