chain getting stuck between rear cogs

[stickville]

I have a Fierte Carbon I purchased at the end of last year that came with Sram Rival and a compact crank. I love the bike. When I am in the larger cogs and I shift to the small chainring, the chain goes between two of the rear cogs. This happens intermittently and usually when starting a climb. My LBS said everyting looks ok and did not make any adjustment. My LBS said they have never seen this happen. The chain is a Shmiano HG 5600 which appears to be a 105 chain. Is this chain incompatible with Sram? Is the chain too long such that there is not enough tension and the chain jumps off the cog? Or is the problem "user error"?

[AngryScientist]

a 10-sp chain should not fit in between the rear cogs of a 10-sp cassette. thats the whole point.

i suspect there is something wrong with your rear cassette, possibly put together wrong with the wrong spacer size or doubled up on spacers between the cogs. something is amiss.

your lbs sounds terrible if they think everything is OK and your chain is slipping between rear cogs.

find a new mechanic, or read up on the proper spacing between rear cogs, or just buy a new rear cassette. those are your options.

[TAW]

A couple of questions: Are you running a Rival crank and bottom bracket?
And if you shift to the small front ring and the small cog in the rear, does the rear der. have clearance between the chain? How does the rear derailleur sound when it IS in a gear?

If you were in small front ring and small rear gear, it could be a crosschain problem, but to me it sounds like a rear derailleur adjustment problem if you are in small front and big rear and it doesn't find a gear.

[AngryScientist]

A couple of questions: Are you running a Rival crank and bottom bracket?
And if you shift to the small front ring and the small cog in the rear, does the rear der. have clearance between the chain? How does the rear derailleur sound when it IS in a gear?

If you were in small front ring and small rear gear, it could be a crosschain problem, but to me it sounds like a rear derailleur adjustment problem if you are in small front and big rear and it doesn't find a gear.

no. the chain should not slip between the rear cogs under any circumstances, regardless of RD adjustment. the spacing of the rear cogs should prevent this. something is amiss with his cassette.

[stickville]

I used the wrong term, the chain is not getting stuck, as in lodged between two cogs, but instead skating between two cogs and not engaging.

The owner of my lbs is having relationship issues and is leaving his shop to skateboard boys who are not the best bike mechanics. The shop does not sell Serrota. I will find a new mechanic.

I am not sure what bottom bracket is on the bike. The problem seems to only occur when in the cogs with the more teeth (larger cogs) and the small chainring(34T).

[AngryScientist]

ahh, thats a horse of a different color. the culprit is most likely cable tension.

this is very very easy to check/fix. visit the park tools website and review their procedure for setting up the RD. the limit screws shouldnt be touched. work with the rear barrel adjuster and vary the cable tension according to the procedure.

rest assured, you really can screw anything up doing this, and even a novice should be able to dial in the cable tension following the procedure, though it may take a little fiddling.

trust me, you can fix this yourself,

[MattTuck]

I'm not the person who should be giving advice when it comes to wrenching, but my go to solution any time I have shifting issues is to give the chain, cogs, derailleurs, jockeys, etc. a good cleaning and lubing.

I find that solves many of my problems.


+2 on finding a new mechanic. I've noticed that more and more, you bring a bike in to be looked at, the shop takes no effort to replicate the problem you complain of, tell you it looks good, and sends you on your way. infuriating.

[stickville]

I will check out the park site and make sure all pullys are clean and lightly lubed.

[Ralph]

In addition to the common sense things, it sounds to me like it just needs adjusting. Very simple to do. You can probably fix it with the barrel adjuster at the RD.

[Louis]

My LBS said they have never seen this happen.

In that case they must have been born yesterday. An out of adjustment rear dérailleur has to be one of the most common things in the world.

First thing I usually try to figure out is if I'm pulling too much or not enough cable.

This sort of thing is worth figuring out yourself so I suggest that you take the time to understand how the barrel adjuster works. (On mine turning the adjuster "in" causes the housing to get "longer" which in turn tightens the cable which in most r-ders causes them to move up to a bigger cog - at least for me it's counter intuitive because the barrel adjuster acts like a fixed nut and the housing the bolt, so when you turn the barrel in a direction that make it move one way for a right-hand thread the cable housing actually moves in the other direction. I think I got the right.)

I hope that that doesn't just confuse you even more...

Louis

[palincss]

On mine turning the adjuster "in" causes the housing to get "longer" which in turn tightens the cable which in most r-ders causes them to move up to a bigger cog - at least for me it's counter intuitive because the barrel adjuster acts like a fixed nut and the housing the bolt, so when you turn the barrel in a direction that make it move one way for a right-hand thread the cable housing actually moves in the other direction. I think I got the right.


That's exactly backwards from the way every adjuster I've ever seen works.

Adjusters have right hand thread, so turning the adjuster "in" (i.e., clockwise) causes the adjuster to get shorter, which reduces cable tension. Turning the adjuster counter-clockwise lengthens it, thereby increasing tension on the cable.

Depending on whether you have a "normal" or "ass-backwards" rear derailleur, that will move you towards the larger or smaller sprockets.

[TAW]

I believe Louis is referring to the rear der adjuster, and turning it "in" meant turning it toward the bike which is counter clockwise from the back of the bike.

[Louis]

OK, from the Park Took web site, where they do a better job explaining it:

Index Setting

A) Set limit screws (if not already done).

B) Shift chain to outermost rear sprocket (smallest). Shift chain to outermost (largest) chainring in front.

C) Test initial inner wire tension. Pedal a normal cadence and shift rear derailleur with one click on lever. Use care to only move lever one position. If derailleur moves one sprocket, tension is adequate.

D) If derailleur fails to shift one sprocket, inner wire may be too slack. Turn barrel adjuster fully into derailleur body (or shift lever) then turn counter clockwise two turns to allow for index adjustments. Loosen inner wire pinch bolt and gently pull on inner wire with fourth hand tool or pliers to remove slack. Tighten inner wire pinch bolt.

E) If derailleur will not shift one sprocket after removing slack in "d", return lever back to outermost sprocket position and increase inner wire tension by turning barrel adjuster counter-clockwise 1/4 turn and attempt shift again.

F) Shift to second sprocket in rear. Pedal and increase inner wire tension by continuing to turn adjusting barrel counter-clockwise until a definite rattling is heard. Rattle is from chain scrapping against next sprocket.

G) Once a too-tight rattle is achieved, turn barrel adjuster 1/4 turn clockwise, to release inner wire tension, and pedal again. Listen and look for signs of scraping or rattling. Continue turning barrel adjuster 1/4 turn clockwise at a time until rattle disappears.

H) Shift derailleur one sprocket inward at a time, listening for signs of rattle, indicating a too tight inner wire. Turn adjusting barrel 1/4 turn clockwise to eliminate rattle. Note: Do not attempt shift to largest rear sprocket while in largest front sprocket. This gear is normally not used and adjusting tension to this shift may compromise other commonly used gears.

I) Shift to innermost (smallest) chainring and check gears again. If no rattling is present, index adjustment is done.