&$?@ing derailers!

My derailer on my mtb is having some kinda wierd issue.

In gears 5-7 it makes a noise and a sensation through the pedals, that i can only describe as loose and crunchy.
Gear 5 is the worst, gear 6 not as bad and on gear 7 it just barely does it at all.

There are no ghost shifts or failed shifts anywhere in the entire gear range.

Theres no play in the cassette or any of the individual cogs.

Im pretty sure the phenomenon is not originating from elsewhere since it occurs only in certain gears.

Im going to try replacing the chain, but it really aint that old. The cassette itself has been ridden pretty regular since early '09.

Any ideas?

This is why i hate derailers!

I would check is the pulleys. Pop the chain off them and spin them in your fingers to see if the bearings/bushings are still good. Sometimes when you shift into different gears the chain pulls them to different angles. If they are worn they can cause problems. As weird as this sounds also check to make sure one is not bent. It does happen.

Next, make sure your hanger is straight. It can be a little bent and shift fine, but can be out just enough to not line the chain up properly.

Finally, if it Shimano, check the B limit screw. It is the screw on the back that controls how far forward the derailleur is swung up. It pulls more tension on the chain. In those gears that more than likely not the issue as you would have problems in the bigger cogs on the back.

I still have all my tools here and will not be leaving until the 6th of August. If you need help let me know.

I agree with Slim...again. B-screw, though it doesn't usually come out of adjustment unless the derailleur is getting old and springs are wearing. Derailleur hanger would be my second guess.

The B-tension screw can most certainly affect the middle range gears. For Shimano, the spec is tight- like 3mm off the large cog. Sram's new spec is huge, 12mm or so, but it makes a hell of a difference. Last week, was having unreliable shifts in the mid range even though indexing was perfect, and a check to the B-tension fixed it.

Bent hangers or cages will be most apparent when cross-chained.

If your limit screws are set correctly, and your cable has stretched like they all do, you will have shift issues in the middle gears while the outer gears may hold fine.

Lastly, Sheldon Brown is a tool. It is nice of him to host so much information, but his opinions are only opinions- so here's mine: It is spelled derailleur.

I can help you out on Sunday if you don't have it resolved by then.

Slim wrote:I would check is the pulleys. Pop the chain off them and spin them in your fingers to see if the bearings/bushings are still good. Sometimes when you shift into different gears the chain pulls them to different angles. If they are worn they can cause problems. As weird as this sounds also check to make sure one is not bent. It does happen.

Next, make sure your hanger is straight. It can be a little bent and shift fine, but can be out just enough to not line the chain up properly.

Finally, if it Shimano, check the B limit screw. It is the screw on the back that controls how far forward the derailleur is swung up. It pulls more tension on the chain. In those gears that more than likely not the issue as you would have problems in the bigger cogs on the back.

I still have all my tools here and will not be leaving until the 6th of August. If you need help let me know.

Thanks... I was wondering if it might be in the pulleys, and my next step, aside from replacing the chain, which won't hurt anything anyway, was to check the pulleys. They ARE visibly worn and pretty roughed up, and I've been lookinf or an excuse to replace them with some more blingy carbon ones anyway...

I'll try these things and if it still doesn't work out I'll bring by.

eurotrash wrote:The B-tension screw can most certainly affect the middle range gears. For Shimano, the spec is tight- like 3mm off the large cog. Sram's new spec is huge, 12mm or so, but it makes a hell of a difference. Last week, was having unreliable shifts in the mid range even though indexing was perfect, and a check to the B-tension fixed it.

Bent hangers or cages will be most apparent when cross-chained.

If your limit screws are set correctly, and your cable has stretched like they all do, you will have shift issues in the middle gears while the outer gears may hold fine.

That's the thing, I'm not having any shifting issues at all. Shifts into and out of all gears just peachy.

eurotrash wrote: I can help you out on Sunday if you don't have it resolved by then.

If it ain't fixed by then, I'll just ride one of my Singlespeeds. I'd rather do that then try to dick around with a deeraylor at 5 a.m.... and AFTER riding 100KM plus I SURE as heck ain't gonna feel like messin' with d'rey-lirs!

If it's a lumpy-gravelly sound that bumps with each chain link bushing that passes through, and indexing/shifting is fine, then it probably is the B-tension. Give it two turns in, and see if that fixes it.

Another thing I just thought about...new cassette/old chain, old cassette/new chain, or even a chain/cassette combo that hasn't been worn together can cause it too. Will sound like it is grinding rocks and it will sound like it isn't "in" the gear, but still shift fine.

spookyload wrote:Another thing I just thought about...new cassette/old chain, old cassette/new chain, or even a chain/cassette combo that hasn't been worn together can cause it too. Will sound like it is grinding rocks and it will sound like it isn't "in" the gear, but still shift fine.

That's exactly what it sounds like... and yeah the chain is MUCH newer than the cassette.... hmmm maybe a new cassette and chain... maybe a deerraylor while I'm at it... maybe upgrade to X speed....

I would check for Gremlins in your bike storage area. Yes, that is the extent of my bike mechanical skills.

Slim,

Sent you a PM.

Going back to exclusively SS is starting to tempt me again...

You have come so far...why turn back now?

spookyload wrote:You have come so far...why turn back now?

Because biking is supposed to bring me joy... not problems to solve.

I am a stubborn bastard, but I am very happy with the move to 10-speed. You can run a 34 up front as a single ring, and have a fantastic range covered... yep, you need a new rear-dee and cassette, plus a shifty thing to go with that new chain.

Actually ive read you can get away with a 9 spd derailleur if you use a 10 spd road shifter for flat bar...

Slim wrote:I would check is the pulleys. Pop the chain off them and spin them in your fingers to see if the bearings/bushings are still good. Sometimes when you shift into different gears the chain pulls them to different angles. If they are worn they can cause problems. As weird as this sounds also check to make sure one is not bent. It does happen.

Dude, yer a genius. The old pulleys were pretty rough. I cleaned them best I could and one was NOT bad, but the other sounded like gravel chewing while rotating. I replaced them both and also replaced the chain at the same time... Problem solved.

Glad I solved this problem prior to Sunday's ride too, because while I'm sure I could have survived it SS, it would not have been as enjoyable as it was with a bike where I have a couple of fluffier gears to back down to when needed.

Put the old chain back on and I bet you will find it making the noise again. Old chain new cassette or vice versa is the most common cause of unexplained noise.

spookyload wrote:Put the old chain back on and I bet you will find it making the noise again. Old chain new cassette or vice versa is the most common cause of unexplained noise.

Not so sure... the sound the pulley made when I rotated it in my hand was almost EXACTLY the sound that I originally noticed. Not saying it COULDN'T be the chain, just saying my intuition says it was the pulleys in this case.