chain feels rough in largest cog

[Stingray34]

I got my hubs serviced this week and the mechanic straightened my wheels a little while he was at it. I had a bit of play in my hubs.

I cleaned my chain, pulleys and cassette and used some new lube (Rock n Roll Extreme - the blue one). I didn't use any degreaser and I didn't soak the cassette: just cleaned the cogs with a rag.

When I put the wheels back in the frame the derailleur skipped a little and I had to readjust it. I got it working really smoothly again except I have a problem in the small chainring/largest cog (34x27). The chain feels rough in this combo.

I checked the RD high/low adjustment and for FD rub, but they're fine. I can make it smooth again by manually pushing the derailleur closer to the wheel in the 34x27, taking up the tiny amount of slack in the indexing. Turning the barrel adjustor also doesn't make the roughness disappear.

I'm unsure what has occured, except that thouroughly cleaning the running gear has made the imperfections noticeable again (I remember when I got the bike 2 years ago there was a similar roughness in the small ring/large cog), the dish on the wheel has been altered or that the play in the hub masked the problem.

All the other cogs are super smooth. Could the problem be related to the large 27 tooth sprocket? I rarely use it and will get a 25 when the cassette needs to be replaced.

Any ideas would be appreciated.

 

[Hawkwood]

I recently took the jockey wheels off cleaned them, and put them back on the gear. When I came to run through the gears they were jumping. For a while I couldn't work it out until I realised that Campag wheels are designed to rotate in a specific direction. Once I refitted the wheels everything worked okay. Not sure what set-up you've got, but it might be worth checking that the jockey wheels are correctly installed.

 

[Stingray34]

I recently took the jockey wheels off cleaned them, and put them back on the gear. When I came to run through the gears they were jumping. For a while I couldn't work it out until I realised that Campag wheels are designed to rotate in a specific direction. Once I refitted the wheels everything worked okay. Not sure what set-up you've got, but it might be worth checking that the jockey wheels are correctly installed.

That's interesting. I've never taken the pulleys off so I assume they're in right. My derailleur is an 09 Dura Ace, the nice shiny version before the current grey incarnation.

 

[Hawkwood]

That's interesting. I've never taken the pulleys off so I assume they're in right. My derailleur is an 09 Dura Ace, the nice shiny version before the current grey incarnation.

It might not be an issue at all with Dura Ace, plus if you haven't taken the jockey wheels off it doesn't sound like that would be the cause. Have you checked the screw for limiting the distance the gear moves is correctly set?

 

[Stingray34]

It might not be an issue at all with Dura Ace, plus if you haven't taken the jockey wheels off it doesn't sound like that would be the cause. Have you checked the screw for limiting the distance the gear moves is correctly set?

Yeah, I loosened the RD L screw a half turn to bring it closer to the spokes but it didn't make any difference, so I put it back to its original position. It's a sort of rough, rhythmic grinding in that particular cog/chainring combo.

 

[brianf7]

Make sure all the limiters are set exact in line then start off with top gear and shift to 3rd gear it should be perfect in that gear and all others should fall into place.
Make sure the chain is not rubbing on the front mech. if it is you need to adjust that slightly or if you dont use the 27 leave it alone.

 

[dsut4392]

If pushing the derailleur towards the spokes fixed it, it sounds like you need to back off the low gear limit screw and increase cable tension. If that didn't fix it, check the b-tension adjuster screw - if there is insufficient b-tension the derailleur jockey wheel could be touching the cassette. I have seen cases where the b-tension adjuster screw has slipped off the frame tab allowing all the tension off.

 

[TERMINATOR]

I got my hubs serviced this week and the mechanic straightened my wheels a little while he was at it. I had a bit of play in my hubs.

I cleaned my chain, pulleys and cassette and used some new lube (Rock n Roll Extreme - the blue one). I didn't use any degreaser and I didn't soak the cassette: just cleaned the cogs with a rag.

When I put the wheels back in the frame the derailleur skipped a little and I had to readjust it. I got it working really smoothly again except I have a problem in the small chainring/largest cog (34x27). The chain feels rough in this combo.

I checked the RD high/low adjustment and for FD rub, but they're fine. I can make it smooth again by manually pushing the derailleur closer to the wheel in the 34x27, taking up the tiny amount of slack in the indexing. Turning the barrel adjustor also doesn't make the roughness disappear.

I'm unsure what has occured, except that thouroughly cleaning the running gear has made the imperfections noticeable again (I remember when I got the bike 2 years ago there was a similar roughness in the small ring/large cog), the dish on the wheel has been altered or that the play in the hub masked the problem.

All the other cogs are super smooth. Could the problem be related to the large 27 tooth sprocket? I rarely use it and will get a 25 when the cassette needs to be replaced.

Any ideas would be appreciated.

I am amazed at all the other responses and how utterly wrong they are. The correct answer to this problem is your large cog in the back is the least used cog and has not worn to the chain like the other cogs. The reason why cleaning your drive train exposed the unequal wear is because when you cleaned your chain and the cogs, you removed most of the grease, dirt, and grime that cushioned the chain and softened the feel, which had previously served to hide these unequal wear patterns.

You should just get a new chain. All the other posters appear to have very little knowledge in bike maintenance to have not diagnosed this problem properly.

 

[on3m@n@rmy]

I am amazed at all the other responses and how utterly wrong they are. The correct answer to this problem is your large cog in the back is the least used cog and has not worn to the chain like the other cogs. The reason why cleaning your drive train exposed the unequal wear is because when you cleaned your chain and the cogs, you removed most of the grease, dirt, and grime that cushioned the chain and softened the feel, which had previously served to hide these unequal wear patterns.

You should just get a new chain. All the other posters appear to have very little knowledge in bike maintenance to have not diagnosed this problem properly.

I agree. I was just going to say that checking the chain to see if it has stretched past the point where it should be replaced is the missing piece. If you don't have the tool to check this your local shop will. Another quick check you could do, which may not work if the rings have been worn down due to using a chain too long that is overstretched, is put your FD on the big ring (doesn't matter what gear the RD is in). IF your front ring is not worn, then IF the chain needs replacing the chain will not seat all the way down into the bottom of the teeth. The teeth will tend to make the chain move out and away from the bottom groove of the teeth. To see this you may have to release the chain tension applied by the RD a little, but not too much (by moving the RD arm by hand). BEST tho is to take it to the shop. I'll bet you need a new chain. Depending on use, chains will typically only get about 2000 miles before they need replacing, and maybe sooner if the chain is not cleaned and lubbed periodically but is run dirty most of the time.

 

[Bustedknuckle]

I got my hubs serviced this week and the mechanic straightened my wheels a little while he was at it. I had a bit of play in my hubs.

I cleaned my chain, pulleys and cassette and used some new lube (Rock n Roll Extreme - the blue one). I didn't use any degreaser and I didn't soak the cassette: just cleaned the cogs with a rag.

When I put the wheels back in the frame the derailleur skipped a little and I had to readjust it. I got it working really smoothly again except I have a problem in the small chainring/largest cog (34x27). The chain feels rough in this combo.

I checked the RD high/low adjustment and for FD rub, but they're fine. I can make it smooth again by manually pushing the derailleur closer to the wheel in the 34x27, taking up the tiny amount of slack in the indexing. Turning the barrel adjustor also doesn't make the roughness disappear.

I'm unsure what has occured, except that thouroughly cleaning the running gear has made the imperfections noticeable again (I remember when I got the bike 2 years ago there was a similar roughness in the small ring/large cog), the dish on the wheel has been altered or that the play in the hub masked the problem.

All the other cogs are super smooth. Could the problem be related to the large 27 tooth sprocket? I rarely use it and will get a 25 when the cassette needs to be replaced.

Any ideas would be appreciated.

Check the b limit screw..pulley may be dragging on the largest cog.

 

[Stingray34]

It is the B-tension screw - thanks everyone for you help. By manually moving the cage backwards the chain becomes smooth again.

Only, this screw is already as tight as it can go but the pulleys are still too close to the largest cog.

The cable tension is good; any more would be too tight.

Can I try another longer screw? The DA7800 derailleur is apparently good for sprockets up to 28 teeth, so the cage length shouldn't be a problem.

 

[Jukebox]

What frame is it installed on? Some companies' hangers arent long enough to clear a 28t very well, but 17 should be no problem. Maybe your chian is a little too long, a shorter chain slightly pulls the upper pulley away from the cog as the pulley doesnt pivot on the same point as it spins.

 

[Bustedknuckle]

It is the B-tension screw - thanks everyone for you help. By manually moving the cage backwards the chain becomes smooth again.

Only, this screw is already as tight as it can go but the pulleys are still too close to the largest cog.

The cable tension is good; any more would be too tight.

Can I try another longer screw? The DA7800 derailleur is apparently good for sprockets up to 28 teeth, so the cage length shouldn't be a problem.

A longer screw or your chain is one link too long. If you go big-big combo and the RD has plenty of forward motion left, take out a link.

 

[Bustedknuckle]

I am amazed at all the other responses and how utterly wrong they are. The correct answer to this problem is your large cog in the back is the least used cog and has not worn to the chain like the other cogs. The reason why cleaning your drive train exposed the unequal wear is because when you cleaned your chain and the cogs, you removed most of the grease, dirt, and grime that cushioned the chain and softened the feel, which had previously served to hide these unequal wear patterns.

You should just get a new chain. All the other posters appear to have very little knowledge in bike maintenance to have not diagnosed this problem properly.

Dohhh!!!!

screw driver solution once again!!!

 

[Stingray34]

I just wanna say thanks to everyone for your input; been super busy with work and haven't tried your suggestions yet, but I think the answers are here. My chain has prob stretched.

This is the value of the forums: riders helping each other and not arguing in the clinic!



BTW my frame is a Dale carbon six.

 

[dsut4392]

I am amazed at all the other responses and how utterly wrong they are. The correct answer to this problem is your large cog in the back is the least used cog and has not worn to the chain like the other cogs. The reason why cleaning your drive train exposed the unequal wear is because when you cleaned your chain and the cogs, you removed most of the grease, dirt, and grime that cushioned the chain and softened the feel, which had previously served to hide these unequal wear patterns.

You should just get a new chain. All the other posters appear to have very little knowledge in bike maintenance to have not diagnosed this problem properly.

Nyah Nyah, that'll teach you to be an arrogant so-and-so.

Now go take the last chain you pulled off your bike and give yourself ten lashes for being "utterly" wrong.

 

[ustabe]

Check the b limit screw..pulley may be dragging on the largest cog.

That one gets my vote, too. I got a little of that using my 27, too. Until I gave the B-screw a couple turns. You can test how this will work by just pushing the derailleur body back with your hand while turning the cranks in the stand.