[donpabl0]

I ride an XL Burner (from the last year they were made, I think -got the frame when Supergo was closing them out with the Manitou Swinger on there). I have persistant chainsuck problems. Shifting up front from the middle to granny ring very often causes the chain to get improperly routed (it goes from the rear derailleur up above the chainstay and then down onto the granny ring; it happens when the chain fails to come off the middle ring quickly enough and ends up between the middle ring and the chainstay before the shift is completed). I can pedal like this, but I can't get the chain back out of there without getting off the bike and pulling it out. So far, I've:
-put on a new chain and a new middle ring (since that's the one it gets stuck on)
-adjusted the chainline (yes, I'm using the correct spacers for my bb)
-switched to Boeshield lube

I'm using a very old rear derailleur (XTR, pre-mega-9), and I'm wondering if that's failing to keep chain tight enough as it's leaving the rings. It might be a bit worn out/beat up. Still, it doesn't really seem like the rear derailleur should be the problem behind the shifing on the crankset. Do I need to use some kind of chain tensioner or retention system? It doesn't seem like it should be necessary. The clearance between the crankset and the chainstay is a bit tight, but the chain shouldn't be on the teeth when they're going past the chainstay anyway.

Let me know if you have any suggestions.

 

[tscheezy]

Just to cover the bases, name a few names. Specifically, the make and model of cranks, the brand of chainring and chain.

I have run a few lethal combinations. SUCK-HELL was from the old octalink XTR cranks and a Wipperman chain. Sram chains and Raceface rings, no problems ever.

 

[donpabl0]

I'm running X-type Deus cranks, RF rings too. I had a Shimano ring in the middle, but I just switched back to RF, hoping that would solve the problem. Chain's a PC-950. XT front derailleur, Rocket shifters.

 

[uktrailmonster]

I only ever get chain suck like this on a worn chainring / new chain combo.

 

[cactuscorn]

its possible that if yer rear der is dead, this could be the culprit. easy to check. does the cage swing side to side if grabed at the bottom and moved? if so this can cause a myriad of issues. replace it and try again.
as cheese has said many times, a new ring/chain/casstte combo has some initial burring and can also cause suck. this will go away rather quickly.
another thing to look for is a bent spyder. if this is yer issue, the rings will always have a bend to them and life will be without pleasure.
are ya sure yer usin same/same parts? ive seen a few cases where folks mix 8 and 9spd stuff which wont word as a general rule. very common with mail order shoppers and inexperienced shop help/home mechanics.
good luck with it and let us know how it turns out.

 

[VTT]

I had the same problems with my Burner and switched from Shimano XT rings to Blackspire rings and a new chain. Never had a chainsuck since...

 

[donpabl0]

well, the only thing I'm running that's technically 8spd is that old rear derailleur (and I don't think the width of the der. cage or pulleys is the source of my problem). The rings all have "9SP" etched on them and the chain's 9spd too (PC-950, I think). But it does seem like there's more side-to-side play in the rear derailleur than there should be. So, I'll probably try replacing that. It's long overdue anyway. If it doesn't work, I'll be looking for rough spots on the chainring again, I suppose. Thanks for the suggestions.

 

[bikenut316]

Had the same problem with my Flux. Changed the worn rings, cassette, and chain, problem continued. The only remaing old part was the rear derailer. I gave it a non-expert examination and it looked ok and shifted well. Took a gamble and changed the old xt long cage to a new xt mid-cage. Problem solved. Old derailer must have been worn but still functional and only a problem when stressed it could not hold the chain tight.

 

[cactuscorn]

the pulleys may be some of yer prob too as they dont match up to the chain id but i dont see this bein the big issue at the rings like yer havin. bet the thing is simply dead. get back to us after the swap and dont forget a expert tune of the new part.

 

[donpabl0]

new derailleur

I put a new XT rear derailleur on there over lunch. I'll have to get it out for a ride and see if it helps. I'll let you know. Thanks again.

 

[Jayem]

I put a new XT rear derailleur on there over lunch. I'll have to get it out for a ride and see if it helps. I'll let you know. Thanks again.

Good luck.

Rings aren't that complicated either. If you're getting chainsuck, it's usually attribuatable to the chain "sticking" to the teeth because of excessive side-load, or it's because the rings are worn and the distance between the teeth doesn't match up with the chain anymore, or because there are little "hooks" also caused by excessive wear which trap the chain. If you switch rings and everything clears up, it means that your rings were worn, and rings will wear. I go through a set of rings every year or so. Also, if you have a chain that is too long, and therefore the derailer doesn't put enough tension on it in some gear combos, that would probably help to cause some chainsuck with some very minimal external factors.

If you replace the rings and it doesn't go away, it's either the spacing issue or the chain is worn and the "new" teeth don't match up with the rings. Sometimes the spacing that "should" work doesn't. Also, if there is a minimal variance on the spacing with a particular bike, the user could make it worse by riding in certain gear combos more often than say a different rider.

If you have to replace rings, you probably have to replace the chain. If your drivetrain is seriously worn, and you only replace one of two out of three (rings, chain, cassette) you are most likely going to continue to have problems.

 

[cactuscorn]

all true jay but he says hes got fresh bits bisides the big and small rings where his issue doesnt occur and correct spacing so i gotta trust him. we covered the bent spyder and that leaves a dead 8spd der but its a long shot. this stuff is so hard to diagnose on line. ya just dont know for sure what yer dealin with. i always suggest a good shop take a look at things in person. since im out of a job, that leaves you. you guys want me to find ya a cheap air fare?

 

[Jayem]

all true jay but he says hes got fresh bits bisides the big and small rings where his issue doesnt occur and correct spacing so i gotta trust him. we covered the bent spyder and that leaves a dead 8spd der but its a long shot. this stuff is so hard to diagnose on line. ya just dont know for sure what yer dealin with. i always suggest a good shop take a look at things in person. since im out of a job, that leaves you. you guys want me to find ya a cheap air fare?

Yes and no. As you know, sometimes you gotta do "stupid stuff". Every once and a while you'll get a part out of spec, or the bikes BB will be out of spec. When everything else is ok, sometimes these crazy things are the problem, and they have to be looked into. My main point was that there usually has to be a reason.

 

[cactuscorn]

absolutely correct and a good point. hence my constant harrassing for folks to go to a good lbs. did i mention he should go to his local shop and have them look at things? i did? good. thought id missed that. hehe

 

[donpabl0]

okay so far...

I took the bike up to Walker Ranch last night and did the loop (7.6 miles). We had a little rain yesterday, so Walker wasn't very dusty. I didn't use the granny much, but when I did want to drop down, it worked (no chainsuck). I didn't try to make it shift under heavy pedal pressure or anything; basically, I didn't actually try to make the chain stick just to see if it would. So, I don't know if the problem's completely resolved, but it seems better so far.

I do most of my own work, but when I can't fix something, I take the bike to a shop. About a week ago, I took the bike over to Sports Garage (because of the chainsuck). I think their mechanics are pretty good. They looked at it and suggested a new chainring (although the one I had wasn't exactly old). The chain was new (one ride on it) and so I added the new ring to match the new chain. The problem continued and that's why I picked up a new rear derailleur (which seems to be working so far, see previous paragraph). It definately shifts cleaner on the cassette, which would suggest that the old rear derailleur wasn't cutting the mustard anymore.

Thanks again for the advice.

BTW, on the strong suggestion from the guy at Excel Sports, I got the long-cage derailleur. He had the mid-cage, but said that it wasn't made to work with a 3-ring set-up, and that I wouldn't get enough chain wrap when using the big ring. Do the "cleaner shifts" people claim to get from a mid-cage come at the expense of limited gear choices? I do get into crossed-up combinations at times (though never 22/11 or 44/32). I guess derailleur cage length is a subject for the "drivetrain" board.

 

[cactuscorn]

sounds like life is better. congrats and i hope this simple change fixes yer issue. stick with the long cage SGS unless ya go to 2 rings. a GS der will cost ya far more than the purchase price if used on yer current set up. bent rings, spyder, cassette, chain, ders, hanger and some killed cables and housing to name a few.