[scrodd]

My roadbike works perfectly in all eays except for the smallest sprocket on the cassette.

the chain will occasionally jump, especially when I’m on a sprint and putting pressure on the cranks.

I tried the cable tension adjusting barrel; adding tension to the cable didn't work.

Is it the:

Chain - and tighten the cable?
Cable - Should I loosen the anchor bolt and tighten the cable? Should I replace the cable? Including the housing?
Something else? I don't know if I'm missing anything.

Here's a better description of my problem when I wrote about it previously.

Can someone help me out here so I can solve this before I do a century ride?

 

[C-40]

none of the above...

You need to define "jumping" as opposed to skipping. Skipping is when the chain stays on the proper cog, but skips over some of the teeth in a jerking fashion under a heavy load. This is caused by a worn out cog, usually with a new chain. The fix is a new cassette.

Jumping has the chain moving either to the left or the right of the intended cog. Since your problem is with the smallest cog, a jump to the left would be the next larger cog. That would either mean the cable tension is too high and/or the high limit screw should be turned CCW a small amount to move the RD slightly right. Cable tension adjustments should always be done in 1/4 turn or smaller increments. Full turns or more will place the RD between two cog and mess everything up.

A jump to the right would have the chain hitting the frame and probably jamming up. I don't think that's your problem, but it would mean the high limit screw needs to be screwed in (CW) slightly.

RD adjustment isn't rocket science, you just need to get the high and low limits correct and enough cable tension for the shifts to larger cogs to execute properly. If the shifts in the opposite direction, to smaller cogs, hesitate, you've got too much cable tension.

 

[Mr. Versatile]

As usual, C40 has nailed it.

 

[CleavesF]

It can also be a bend derailleur hanger or derailleur (pulley assembly or body).

 

[uncle]

Just curious how worn your chain is. As C-40 mentions, you can get skipping when a new chain is combined with worn cogs. The same thing can happen when a casette is new and the chain is worn.

 

[Dizzy812]

A new chain can require a new cassette depending on wear.

 

[scrodd]

chain & cassette

Actually, the chain is brand new, it has less than 150 miles on it. I believe the cassette is the original that came with the bike.

Any recommendations on a replacement cassette?