Chain Dropping.....

michael.su

michael.su

Master of the Pawpaw
My bike is a 2001 K2 Attack. Basically It's an XC full suspension.
I have only one annoying issue with it. Hopefully you good MTBNJ peeps can get me sorted out. 😀
When I take any kind of slightly bumpy high speed downhill section, (no peddling) many times my chain jumps off of the front chain rings. Sometimes it just jumps to the granny and other times it jumps all the way off making me stop before the next climb 🙁
Everything is tuned up, It shifts great. My components are all LX/XT. My chain and cassette are new. I've had the problem since I first got the bike ~ 3 years ago.

This is my bike:
IMG_6719.jpg


anyone have any ideas?

Maybe there is some kind of stop/guide I can buy?

Thanks!

-Mike
 
My uneducated first thought (assuming everything is in fact working ok) would be chain length. John@Marty's took a link or two out of mine on the first tune up. I did occaisionally drop it beforehand especially on a rough DH, much less now. Again, assuming nothing is broken or mal-adjusted.
 
+1. deff check the chain length. If this has been an issue from day one.. could deff be it..

extremedave said:
My uneducated first thought (assuming everything is in fact working ok) would be chain length. John@Marty's took a link or two out of mine on the first tune up. I did occaisionally drop it beforehand especially on a rough DH, much less now. Again, assuming nothing is broken or mal-adjusted.
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I did check the chain length and it looks fine to me but it may work to take 1 or 2 links out... I'll give that a try. A LBS actually put the new chain and cassette on last fall. When I told them that my hub was sticking they swore it was the chain and cassette skipping 🙄. I guess it's possible that they also left the chain too long. 😕
Thanks for the tips!
 
TimWarchol said:
It's an easy mistake for a shop. They could size your chain to the old one and miss it
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I looked at the chain again..I don't think I can take any links out and it still work with all of the gears :-(
It's pretty much the optimal size.

rlb said:
Is the front derailleur too high? Probably not, if it's shifting OK, but still worth a look.
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The front derailleur is tiny bit higher than I'd like but the frame/suspension won't allow me to go any lower with it. :-/

I may just have to make sure I'm on the larger cogs for downhills but I hate having to think about that.

Thanks a bunch guys.

Any more ideas?
 
I used to drop my chain a bunch until one wise soul recommended I turn the front derailleur just a tiny bit out. No more chain drop. 🙂

When recently I had to have some work done on the bike, and the tech did an overall look at the bike and made some much needed adjustments here and there, the chain drop started again. Took it back, asked J to look at it, he turned the derailleur back to the old position and viola no more chain drop again. In that position it looks like it is not 100% adjusted correctly, but it doesnt rub the chain at all, shifts just fine, and seems to keep the chain from dropping off.
 
If you can sacrifice the large chainring up front and replace it with a bashgaurd, you will be able to take out a few more links and even go to a medium cage rear derailiure. That will significantly tightened up your chain to the point that you won't even hear it hit the rear triangle anymore. The bashgaurd will also give you better clearance over logs and other things. Unless you want to pedal faster than 25mph you won't miss the large front ring.
How worn out are you front rings? Are they missing teeth?
 
Arwen's Mom said:
I used to drop my chain a bunch until one wise soul recommended I turn the front derailleur just a tiny bit out. No more chain drop. 🙂

When recently I had to have some work done on the bike, and the tech did an overall look at the bike and made some much needed adjustments here and there, the chain drop started again. Took it back, asked J to look at it, he turned the derailleur back to the old position and viola no more chain drop again. In that position it looks like it is not 100% adjusted correctly, but it doesnt rub the chain at all, shifts just fine, and seems to keep the chain from dropping off.
Click to expand...

This is interesting...So, let me see if I understand this correctly, You twisted the derailleur outwards so that it was no longer parallel with the chain rings? or do you mean adjusted the stop out a little?

pxs231 said:
If you can sacrifice the large chainring up front and replace it with a bashgaurd, you will be able to take out a few more links and even go to a medium cage rear derailiure. That will significantly tightened up your chain to the point that you won't even hear it hit the rear triangle anymore. The bashgaurd will also give you better clearance over logs and other things. Unless you want to pedal faster than 25mph you won't miss the large front ring.
How worn out are you front rings? Are they missing teeth?
Click to expand...

I've thought about this a lot but there are a few occasions that I use the big ring on this bike. In the end, I may do it as a sacrifice. 😉
The middle ring and granny aren't missing any teeth and aren't terribly worn IMO. the large ring has some damaged teeth from hitting rocks and such but they are all still there. 😀
 
i'm with the bash guard fix. give that a shot and shorten the chain.

how old is the RD? long cage/short cage?
 
Are the RD springs/pivots 'snappy' and free-moving?
If sluggish or weak, it can't take up the slack quickly enough. Try some oil in the pivots &/or replacing the springs.
 
woody said:
Are the RD springs/pivots 'snappy' and free-moving?
If sluggish or weak, it can't take up the slack quickly enough. Try some oil in the pivots &/or replacing the springs.
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I'd be leaning this way also. Mike, if you sit on the bike, compress the suspension, and play with the RD a bit, does the chain look droopy or saggy? The RD might be bent or jammed, somehow not using it's full throw. Does it jump off the big ring or mostly the middle and granny? Any play side to side in the swingarm (getting a little out there but never know)?
 
extremedave said:
I'd be leaning this way also. Mike, if you sit on the bike, compress the suspension, and play with the RD a bit, does the chain look droopy or saggy? The RD might be bent or jammed, somehow not using it's full throw. Does it jump off the big ring or mostly the middle and granny? Any play side to side in the swingarm (getting a little out there but never know)?
Click to expand...

Not seeing a million of these things on a regular basis, everything seems good to me. it's been to a shop a couple of times too and nobody has caught anything out of the ordinary.
The chain does look a little saggy when on the smaller cogs front and back but I think that is relatively normal with that big range of gears.
I've never had it fall off of the large gear, and it helps keep it on if i peddle once in a while when I'm bombing down but....that's annoying 😀
 
michael.su said:
I've never had it fall off of the large gear, and it helps keep it on if i peddle once in a while when I'm bombing down but....that's annoying 😀
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I do this as well, and it does help. I have been doing it so long I dont even notice.
As for your question, it is twisted out so it is not parallel. Just a wee bit is all it took.
 
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