What causes chain skip? (Bicycle Maintenance)

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2013-04-05 3:52 PM

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McAllen
Subject: What causes chain skip? (Bicycle Maintenance)

This is a recently developed problem. My chain snapped a few weeks ago and I measured a new one with same # of links and put it on the same cassette (A). Cogs 13T and 14T were skipping. The lowest two gears and the rest of them were fine so I figured the cogs were just worn, because I just ride 13/14 almost exclusively unless I'm stopping or starting; so I replaced the whole cassette with a 10spd shimano Tiagra (B) yesterday. New chain only has ~60 miles on it. Re-tuned the derailleur, it shifts smoothly and there's no ghost shifting or clicking from wanting to go up.

On the road: there is still chain skip on the 14T cog. I rode 13T without noticing much, however 11-12 have a routine clicking sound on the road. Not sure what it is, or what's causing it. Its not chain skip. I lift it up and the clicking is gone.

On the stand: 11t cog skips up to 12 and back down. Its totally sporadic/random. There isn't any pattern to when it happens. it doesn't shift completely but it skips occasionally. 14T doesn't skip (span the pedals for 4-5 minutes)

I didn't ride 11 enough to know if it skips on the road but if it does on the stand it probably does on the road.

Any suggestions? Do I need to remove a link on the chain so there's more tension? I haven't touched the limit screws. The hangar isn't bent or out of place. the pulleys are still vertical.



Edited by odpaul7 2013-04-05 3:54 PM

2013-04-05 3:58 PM
in reply to: #4688709

Master
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Subject: RE: What causes chain skip? (Bicycle Maintenance)
Do you know what the barrel adjuster is? Might need to tweak that a little one way or the other.
2013-04-05 4:02 PM
in reply to: #4688719

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McAllen
Subject: RE: What causes chain skip? (Bicycle Maintenance)

Yeah I've been tweaking the barrel adjustor. Even at the lowest setting the 11t cog still skips up when its on the stand. I even tried maxing out the adjustor, re-tightening the cable, and lowering it all the way again and it still skips up.

I just recently tried lowering the limit screw and it doesn't change much. I almost backed it out, too. Makes me think that something somewhere is bent :/

2013-04-05 4:19 PM
in reply to: #4688709

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Boise, Idaho
Subject: RE: What causes chain skip? (Bicycle Maintenance)
Still sounds like a der. hanger could be bent-LBS can check and straighten.  10 speed drive trains have almost zero tolerance for misadjustments.  Any stiff links in the chain?  Watch it travel over a jockey wheel and see.  Are you certain it's coming from the chain?  Seat/seatpost, handlebar/stem, chainring bolts?  all these can develop a mysterious 'tic' that seems to come and go based on the torque loads of the bike.  Good Luck. 
2013-04-05 4:21 PM
in reply to: #4688760

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McAllen
Subject: RE: What causes chain skip? (Bicycle Maintenance)

I'll check the hangar again and lay it flat on a table.

out of curiosity how do they flatten a hangar? (with luck I'll have a spare lying around :P)

2013-04-05 4:26 PM
in reply to: #4688709

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Boise, Idaho
Subject: RE: What causes chain skip? (Bicycle Maintenance)
LBS has a jig-like tool that screws into the der. hanger and measures the relative distance from the wheel rim.  Der. hangers are fairly soft aluminum so they simply 'tweak' the hanger til it's straight.  CAUTION:  The more 'tweaking' you do the weaker the hanger becomes.  Replacements run about 10-15 bucks.

2013-04-05 5:19 PM
in reply to: #4688772

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McAllen
Subject: RE: What causes chain skip? (Bicycle Maintenance)

Its an integrated hangar.

I checked it again and everything seems real straight. Lined it up on a flat edge and everything.

I just have the cables set so it won't go into the 11t, so 50-12 is the highest gear I'll go. I'll just take it to a shop after this weekend... Some jobs just aren't DIY.

2013-04-05 5:40 PM
in reply to: #4688709

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Champion
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Subject: RE: What causes chain skip? (Bicycle Maintenance)

Had something similar recently.  Finally figured out it was a stiff link in the chain. 

Mark

2013-04-05 5:43 PM
in reply to: #4688839

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Subject: RE: What causes chain skip? (Bicycle Maintenance)
RedCorvette - 2013-04-05 7:40 PM

Had something similar recently.  Finally figured out it was a stiff link in the chain. 

Mark

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2013-04-05 5:48 PM
in reply to: #4688839

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McAllen
Subject: RE: What causes chain skip? (Bicycle Maintenance)
RedCorvette - 2013-04-05 5:40 PM

Had something similar recently.  Finally figured out it was a stiff link in the chain. 

Mark

negative. went through each link individually and they're fine :l also inspected as they went over pulleys. Nothing wrong there.



Edited by odpaul7 2013-04-05 5:49 PM
2013-04-05 6:06 PM
in reply to: #4688709

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McAllen
Subject: RE: What causes chain skip? (Bicycle Maintenance)
This is just a real shoddy time to have something go wrong. Man fixing stuff on bikes is a slippery slope. When one thing goes wrong, LOTS of things go wrong -.-

2013-04-05 8:48 PM
in reply to: #4688709

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Subject: RE: What causes chain skip? (Bicycle Maintenance)
Does your new chain directional? Some have an outside and inside shape to the links.

Was your old cassette also a 10sp one?

Is your new cassette fully seated on the cassette body?

Your old chain would have stretched out due to wear. You don't want the new chain to be the same length as it will also get a little long over time.

Sometimes with things like this I just start over. Undo the derailure cable and start proper alignment of the RD over the inner cog and then same for the outer cog. Seems to be easier and faster than messing with things to kinds get it dialed in for me. Sounds like your old chain was pretty worn and maybe so was the cassette, replacing them will toss things off.
2013-04-05 9:59 PM
in reply to: #4688966

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McAllen
Subject: RE: What causes chain skip? (Bicycle Maintenance)
magic - 2013-04-05 8:48 PMDoes your new chain directional? Some have an outside and inside shape to the links. Was your old cassette also a 10sp one? Is your new cassette fully seated on the cassette body? Your old chain would have stretched out due to wear. You don't want the new chain to be the same length as it will also get a little long over time. Sometimes with things like this I just start over. Undo the derailure cable and start proper alignment of the RD over the inner cog and then same for the outer cog. Seems to be easier and faster than messing with things to kinds get it dialed in for me. Sounds like your old chain was pretty worn and maybe so was the cassette, replacing them will toss things off.
The old chain cassette and chain were like 1200 miles but when it popped I just didn't wanna deal with it and got a new chain (I lube every week and keep it clean. Even mistreated should get 1500 though). I don't believe its directional. Both are 10sp, I matched up the same # of links. I might start from scrap again and see how it works. I need new cable too ASAP, recently discovered. It's fraying from the middle so it's clamped on as many strands as I could get. I really hope nothing is minutely bent I don't wanna replace parts -.- would the cable potentially be an issue? Will it be elongated over less strands?
2013-04-05 11:06 PM
in reply to: #4688846

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Subject: RE: What causes chain skip? (Bicycle Maintenance)
odpaul7 - 2013-04-05 3:48 PM
RedCorvette - 2013-04-05 5:40 PM

Had something similar recently.  Finally figured out it was a stiff link in the chain. 

Mark

negative. went through each link individually and they're fine :l also inspected as they went over pulleys. Nothing wrong there.

Well, that was going to be my suggestion, but if you checked it out...Good luck.
2013-04-06 6:49 AM
in reply to: #4688709

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Davenport, IA
Subject: RE: What causes chain skip? (Bicycle Maintenance)
You have the 10spd spacer in behind the cassette, right?  And only one of them?  If you have two back there it could cause exactly what you're talking about.  It could also be an issue of the cassette lockring not being tight enough.
2013-04-06 8:29 AM
in reply to: #4689160

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Davenport, IA
Subject: RE: What causes chain skip? (Bicycle Maintenance)

Sprint_DA - 2013-04-06 6:49 AM You have the 10spd spacer in behind the cassette, right?  And only one of them?  If you have two back there it could cause exactly what you're talking about.  It could also be an issue of the cassette lockring not being tight enough.

 

Unless, of course, it's a SRAM cassette, then make sure there is no spacer at all behind the cassette.



2013-04-06 9:53 AM
in reply to: #4688709


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Subject: RE: What causes chain skip? (Bicycle Maintenance)
This is not uncommon when you run a new chain on older cogs. The cogs have worn to match the old chain. You may just need to ride it and put up with it until it gets worn in, or you may need to replace the cogs it's skipping on.
2013-04-06 1:14 PM
in reply to: #4688709

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Subject: RE: What causes chain skip? (Bicycle Maintenance)
I've never met a drivetrain I could't get running smoothly. After checking/adjusting all the usual suspects - new chain, new cassette, cassette spacers different from the old to the new, stiff chain link, barrel adjusters, inner and outer limit screws, worn derailleur jockey pulleys, wheel positioned correctly in the dropouts - it's come down to derailleur hanger alignment. If that's off, then working on everything else will be futile. Mountain bike derailleur hangers get knocked out of whack all the time, but on a road bike, unless you've crashed on your drivetrain side, or had your bike fall over on that side, it's not a common occurrence. If you do take it to a shop and they get it right, update us with the fix.
2013-04-06 1:53 PM
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McAllen
Subject: RE: What causes chain skip? (Bicycle Maintenance)
Yeah I'll do another run through of everything you listed again before I take it in Monday. Its a total mystery -.-

I had a race today and the highest gear skipped a little with the added riding tension and one of the cogs skipped once or twice. However I also consciously stayed on the gears I knew worked well so that might have helped.
2013-04-06 2:20 PM
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