[Shayne]

I've read over most of the other chain skipping issue threads but none of them really answered/resolved my question.
Ok, here's the situation:
9spd Ultegra cassette
9spd Shimano chain (dont remember the model but it was pretty cheap)
Joe's derailleur (I know these are very hit and miss but it worked flawlessly in a different application)

It shifts perfectly through the largest 5 cogs. It also stays put in the smallest cog. The 6,7,8 position cogs however will not operate smoothly. The chain is always trying to move up to the next largest cog. I have adjusted the cable tension both ways enough to shift it to another cog but it will still try to jump up to the next cog if it's in that range.

The chain and cassette are matched wear wise so that shouldn't be an issue. They were used on another bike and shifted fine there.

My only thought is picking up a higher quality chain at this point but don't want to drop the money if I dont have to.

 

[Bikinfoolferlife]

You check the derailleur hanger alignment?

 

[Shayne]

Looks good to my eyes

I havent used the official tools but by eyeballing it it appears fine.

Wouldn't that cause problems in all cogs though?
That's been my previous experience.

 

[Bikinfoolferlife]

I've had bent hangers that only affect a part of the cogset. You can't necessarily tell by eyeballing it (at least my eyeballs have never been as good as my gauge).

 

[Kona0197]

the teeth on the 6,7 and 8 cogs might be bent. Thats the only thing I can think of.

 

[Jm.]

I havent used the official tools but by eyeballing it it appears fine.

Wouldn't that cause problems in all cogs though?
That's been my previous experience.

Nope, a great indicator of a bent hanger is when it shifts fine in some gears, but poorly or not at all in others. Your eyes can not tell you if the hanger is bent.

Ocassionally pulleys will get real loose and wobble around a bit, sometimes that gives enough play to let it "wander" a little.

I just (finally) fixed a problem on a womans bike today where her chain was "slipping" off the large rear cogs onto the next gear down. She told me this many times, but we kept looking for problems in the derailer/cogs and didn't really find anything there. We test-rode the bike a LOT and couldn't re-create the problem at all, which makes it pretty tough to fix as well. Finally I asked if the gear inidcator was moving when it "slipped" to a different gear, and she said that it in fact was moving. That means it was a bad shifter that was letting it "slip" down to the next higher (smaller) gear.

Your problem shouldn't be related to this, but the point is that communication can be at the root of many problems, because it's hard to know what the customer is saying exactly, and it's hard to know as a customer what information the mechanic needs.

Bent teeth could do it, but that should be fairly obvious too.

 

[Shayne]

Any Other Ideas?

Just had the hanger alighed/straightened at a shop and threw a new derailleur on for fun and still have the same problem.
As I said in the original post the cassette and chain were used together on another bike and worked flawlessly.
I just dont get it?!?

 

[uktrailmonster]

How old is this chain/cassette combo? They don't last forever you know.

 

[Shayne]

Maybe 500 miles

They were used for 1 season (6 months) on my 3rd bike

I usually get 2k out of a chain and 2-5k out of a cog set

 

[uktrailmonster]

They were used for 1 season (6 months) on my 3rd bike

I usually get 2k out of a chain and 2-5k out of a cog set

You definitely get your money's worth then. I treat chains and gear cables in particular as disposable items. I can't stand riding with worn drivetrain parts. The number of people I see on the trails with shagged out drivetrains, creaking, groaning and slipping their way along never ceases to amaze me. Perhaps it's just because I'm a mechanical engineer?

 

[Hecubus]

You say you moved the chain from another bike. Did you check for the possibility of a stiff link after reinstalling? The would probably screw up shifting all across but sometimes smaller cogs can exagerate the effect because the have less teeth grabbing the chain.

 

[Shayne]

Maybe

I don't think so but I'll check it out tonight.

 

[WesternMD]

Shifter issue...

If all is well with the wear of the chain and cassette and only skips on the current bike and not on the bike it came of if could very well be a worn shifter not indexing the shifts properly. Try flushing with liberal amounts of WD40 if it is rapidfire. This will flush residue. This will not fix worn shift indexes within the shifter. Often overlooked but common.

 

[Jm.]

What? You are saying that the WD-40 doesn't help with a shifting index problem and you don't think that it's a shifting index problem, but you are recommending it anyway?


Here's what I've noticed as a bike mechanic that has no problem diving into rapid fire shifters;

Don't spray anything on there unless you know what you are doing. Use carb cleaner and use the long tube that comes on the bottle. You MUST position it so that it blows RIGHT into the pawl springs (those are what get gummed up in the shifter). Don't use WD-40, don't use anything else. You want to destroy that gummed up grease and get it out of there. You must also work the pawls back and forth till they move freely. I like to lube them with dry-slide after doing this.

Using WD40 on any bike part is usually a bad idea. It's a penetrant, usefull for removing stuck bolts/parts ocassionally, but gummed up shifters are the way they are because of gummed up grease, so use the proper tool for the job.

 

[MikeDee]

Use carb cleaner and use the long tube that comes on the bottle.

Is carb cleaner safe on plastics and painted surfaces?

 

[Jm.]

Is carb cleaner safe on plastics and painted surfaces?

If you do it right, you are doing it with the covers of the shifter removed, and by concentrating the stream around the pawl spring, minimizing the contact with other parts of the shifter. With the shifter "open" the carb cleaner will evaporate before it does anything to the plastic. I wouldn't do it without having the shifter open though.

 

[Shayne]

It Was A Chain Issue

Picked up a new chain and it works like a charm now.

 

[WesternMD]

What I meant...

If it is an indexing problem it could be one of two situations.
1. Debris or residue on indexing system altering shift positions or stops.

2. Worn pawls altering the shift positions.

The flush will clean debris but will not fix worn parts so it will only work on one of the two potential problems. This is the scource of your confusion.

Most home mechanics do not want to dive into the inerds of a rapidfire pod.

WD40 is almost entirely a solvent and does a remarkable job cleaning parts and is safe on virtually all materials. Once it has a chance to evaporate there is only a small amount of lubricant left behind.

Carb cleaner WILL eat paint and plastic and corrode some metals and plating if given a chance. I would not recommend this to an inexperienced wrench.

My suggestions was one that took all of 45 seconds and it really can't mess anything up.
I would hate to see the results when most home mechanics pull apart a rapidfire pod and start in with the carb cleaner. Parts everywhere and melted plastic.

But all is well with a new chain.