Shimano 9-speed skipping mid cassette
 

Hi,

I had a shop tune up my Hilsen with 9 speed Shimano. I know they replaced the rear derailleur as I had experienced poor shifting generally.

I had put a new chain and cassette and front large chainring on a bit earlier as they all had a lot of miles on them.

The bike shifts well except in the middle gear of the cassette. The bike will be noisy and often shift in/out of gear by itself.

Out of frustration, I tossed the (newish) cassette and bought another new one thinking there was something wrong with the cassette. The new cassette is the same as the old cassette and shifts in/out in the middle sprocket.

The cassette is torqued as per spec. New chain, cassette and rear derailleur.
Any thoughts would be appreciated.

Patrick

- Brifter probably is like busted or need cleaning...

- RD hanger is not in the right place, alignment problem.

- You have friction somewhere or a kink in the cable somewhere.

- Did you try just because to add tension to the cable with the cable barrels and see if that stops it? If that kind'a fix it then you have to check all my sugestions...

sounds like cable tension
 

put bike in a stand. turn the cranks and play with barrel adjuster and see if minor tension one way or the other fixes. what rear derailleur? Does it have an adjuster?

thank you
 

I appreciate the input. I will do more checking.

The last resort is to take it back to the shop that did the tune-up as they missed this...

Thank you,

Patrick

What did they say was wrong with the original derailleur? Did the shop have another Shimano 9 speed derailleur lying around? It would be surprising to me if a Shimano 9 speed derailleur was the source of poor shifting as my experience with those derailleurs are that they usually last a long time and have little or no issues. At the most, I have taken out the pulley wheels to clean and lube them. So long as the parts were compatible with one another, my shifting problems have always been caused by shifter cable adjustments and/or derailleur adjustments.

Tight link?

Appreciate the help
 

Hi Five thumbs. The shop said the derailleur had gone 'soft' and was not able to extend to its full range of movement. I expect that means a spring had kind of lost its full dynamic range of motion, or something like that.

Hi OP. The bike runs smooth in all the bigger sprockets and smaller sprockets and only acts up on the middle one. I will check the chain. Good idea.

Thank you,

Patrick

I know nothing but wonder if a derailer had "gone soft" why would it cause problems in the middle of its travel and not at one extreme or the other?

I was thinking the same thing, the issue is right in the middle, that is the weirdest thing ever, I would just run some wd40 in that thing just in case.

more detail
 

Ken,

Sorry, I didn't provide all details. I had the bike tuned up as it would not shift into the larger cassette gears properly.

I had replaced the chain and cassette and large chain ring as all worn.

The shop did the tune-up and replaced the rear derailleur as it was not able to cover all the gears (gone soft).

The new derailleur had the problem with the centre sprocket. Different problems. Was just going to go down to check the chain as per OP's suggestion.

I appreciate the question and apologize for being less than precise in my note!

Thank you,

Patrick

Ghost shifting or autoshifting among middle cogs of the cassette has usually been resolved by adjusting cable tension on my bikes. It has happened on both my 9-spd MTB and my 11-spd road bike, with both cases happening after a couple months' use on new shifter cables.

cable tension
 

Hi Scott,

I had not checked that but will now. The shop that did the tune up looks to have missed something.

Thank you,

Patrick

Does that ever sound suspicious. I have a Deore XT rear derailleur with over 35,000 miles on it that's been in service since 2002 that shifts fine even though it's got a large gouge in the middle that happened 10 years ago when I crashed on the right side when my front wheel got caught in the crack between two lanes of concrete paving. I've never once heard of a derailleur "going soft" although over the years I have experienced derailleurs that got sloppy because the pivots got loose and wobbly. I frankly do not believe it.

Incidentally, unless it's one of those 'ass backwards' Shimano MTBs, the springs don't pull the derailleur onto the largest sprocket, the cable does. Even without any spring tension at all, the cable would pull the derailleur all the way unless something was blocking it.

If it's just happening on the middle cogs..I'd make sure the cogset is indeed a 9s cogset..I tuned a bike once and the gent said the same thing about shifting, turns out it had a 10s cogset on an otherwise 9s system.

Second, new rear der...road? 10s? It should be compatible. If it's a MTB rear der..has to be a 9s one..10s MTB rear ders not compatible with road 9s STI shifters.

Otherwise maybe just der adjust if everything is indeed compatible.

Did you change the cassette and chain at the same time, or did you change the chain first, followed by the cassette after you put some miles on the new chain If so, your chain might be spent.