Chain skipping issue

SamIAm · #1 07-18-2017, 08:24 AM

Just built up a new frame with Campy 11 drive train. Took it out last night for a shakedown ride and it wasn't pretty.

Chain kept skipping in cogs 8-10 (ordered low to high tooth count) or so. By skipping I mean shifting to the desired cog, but once in cog n (the desired cog), it would try to get to n+1 with the outside of the chain right on top of the next cogs teeth, but then drop back down to n, creating an unsettling thunk. This would happen every few pedal strokes.

Now normally I would just adjust the RD to reduce the cable tension, but there was no adjustment that would resolve this.

I could pull the cable with my hand and get it to track properly, but there was no way to shift it into that position.

Initially it was a new chain with an old cassette, so I replaced the cassette, but it still showed this anomaly. I checked the chain for frozen links, but didn't find any.

The wheel was firmly seated in the drop outs.

I did notice that the chain (which had to be installed by REI mechanic due to not having an 11 speed tool) was probably longer than I would have made it. In the small chainring, smallest 2 cogs, the chain is rubbing the bottom of the derailleur jockey wheels.

The derailleur hanger looks straight as does the derailleur itself.

I'm out of ideas.

Help would be appreciated.

marsh · #2 07-18-2017, 08:42 AM

Quote:

Originally Posted by SamIAm

In the small chainring, smallest 2 cogs, the chain is rubbing the bottom of the derailleur jockey wheels.

REI should have no problem removing a few links for you. Start with 2 links, ride it around the lot and see if everything shifts correctly. It happens to me with new builds when I don't have the old chain to go off of, it's easier to downsize the chain than to up size.

Pierre · #3 07-18-2017, 08:55 AM

have you routed the cable correctly through the derailleur? Is it possible that the cable is catching somewhere? Is the cable tightly fastened? Strange issue. Hopefully the shorter chain sorts you out.

I had something similar happening and it turned out that the wheel builder had built the wheel too far to one side so when in the larger sprockets and under heavy power it would want to jump right out of the gear. Don't think this applies for you but just encouraging you to think outside of the box!

...it IS an 11spd campy chain, right?

Billybob62 · #4 07-18-2017, 08:56 AM

Quote:

Originally Posted by SamIAm

I'm out of ideas.

Help would be appreciated.

Simple things first - make sure cable is running freely at bottom bracket guide.

lemondvictoire · #5 07-18-2017, 09:12 AM

Double check alignment of derailleur hanger with alignment gauge and also if that all bolts hanger and main derailleur bolt are tight.. Fixed a friend's bike that had loose bolts....

oldpotatoe · #6 07-18-2017, 09:15 AM

Quote:

Originally Posted by SamIAm

Just built up a new frame with Campy 11 drive train. Took it out last night for a shakedown ride and it wasn't pretty.

Chain kept skipping in cogs 8-10 (ordered low to high tooth count) or so. By skipping I mean shifting to the desired cog, but once in cog n (the desired cog), it would try to get to n+1 with the outside of the chain right on top of the next cogs teeth, but then drop back down to n, creating an unsettling thunk. This would happen every few pedal strokes.

Now normally I would just adjust the RD to reduce the cable tension, but there was no adjustment that would resolve this.

I could pull the cable with my hand and get it to track properly, but there was no way to shift it into that position.

Initially it was a new chain with an old cassette, so I replaced the cassette, but it still showed this anomaly. I checked the chain for frozen links, but didn't find any.

The wheel was firmly seated in the drop outs.

I did notice that the chain (which had to be installed by REI mechanic due to not having an 11 speed tool) was probably longer than I would have made it. In the small chainring, smallest 2 cogs, the chain is rubbing the bottom of the derailleur jockey wheels.

The derailleur hanger looks straight as does the derailleur itself.

I'm out of ideas.

Help would be appreciated.

-Smooth movement, no drag of inner wire thru housing. Including under BB guide. Housing long enough, no ferrules anywhere in the lever.
-Der Inner wire routed properly on rear der...under fixing bolt, plate.
-Shifters and rear der compatible.
-Wee brass washers not turned sideways, the ones that the der housing pushes against in the lever.
-Tool to check der hanger.
-Rear der cage on correctly(not upside down) and both pulleys in proper place, upper and lower.
-IF you shorten the chain, DO NOT just push a pin out and install a new pin=broken chain. Use a proper snap-link(KMC, I rec.).
-Ya SURE no tight link? Sure sounds like one.

beeatnik · #7 07-18-2017, 09:16 AM

2015 Campagnolo Revolution?

SamIAm · #8 07-18-2017, 09:37 AM

Quote:

Originally Posted by oldpotatoe

-Smooth movement, no drag of inner wire thru housing. Including under BB guide. Housing long enough, no ferrules anywhere in the lever.
-Der Inner wire routed properly on rear der...under fixing bolt, plate.
-Shifters and rear der compatible.
-Wee brass washers not turned sideways, the ones that the der housing pushes against in the lever.
-Tool to check der hanger.
-Rear der cage on correctly(not upside down) and both pulleys in proper place, upper and lower.
-IF you shorten the chain, DO NOT just push a pin out and install a new pin=broken chain. Use a proper snap-link(KMC, I rec.).
-Ya SURE no tight link? Sure sounds like one.

Shifters and RD are both Campy 11.
Derailleur wire is routed properly
No ferrules in lever
Cage on correctly, taken from another bike that was shifting fine
Definitely no tight link, but the rivet that was peened, feels like it might be on the high side, not sure. It doesn't catch at that rivet each time, but does occasionally.
Housing is the correct length and it feels like the cable is moving freely, but I do recall a time where the tension in the run from the shifter to the BB felt different than that between the BB and the RD. The cable is being run through a short section of tubing at the BB.

oldpotatoe · #9 07-18-2017, 09:39 AM

Quote:

Originally Posted by SamIAm

Shifters and RD are both Campy 11.
Derailleur wire is routed properly
No ferrules in lever
Cage on correctly, taken from another bike that was shifting fine
Definitely no tight link, but the rivet that was peened, feels like it might be on the high side, not sure. It doesn't catch at that rivet each time, but does occasionally.
Housing is the correct length and it feels like the cable is moving freely, but I do recall a time where the tension in the run from the shifter to the BB felt different than that between the BB and the RD. The cable is being run through a short section of tubing at the BB.

A der hanger can be off 2mm and have symptoms you are seeing..what frame is this?

SamIAm · #10 07-18-2017, 09:42 AM

Quote:

Originally Posted by oldpotatoe

A der hanger can be off 2mm and have symptoms you are seeing..what frame is this?

A new Richard Sachs.

oldpotatoe · #11 07-18-2017, 09:52 AM

Quote:

Originally Posted by SamIAm

A new Richard Sachs.

I'd still check the der hanger..does it have a bolt on under BB guide? Any way to add one if t doesn't? Many index systems don't like inner wires running on metal. And if the little tube you added is moving with the der cable as you shift.

cpamplin · #12 07-18-2017, 05:56 PM

If it's a used group that you've just moved onto a new frame, try reversing the direction of the chain.

Edit: And protect those shiny new chainstays, if the chain is too long you might get some chain slap.

carpediemracing · #13 07-18-2017, 08:12 PM

Sanity check - it's an 11s chain?

zmudshark · #14 07-18-2017, 08:38 PM

So, to be clear, you have a brand new Richard Sachs frame, a used 11s Campy group of unknown level and a chain that was installed by REI and possibly peened incorrectly, and is too long?

If it were me, I would spring for at least the Pedros chain tool, and learn to install chains at home. I would also buy a derailleur alignment gauge and learn to use it.

Those two tools will save you a small fortune in bad/inattentive bike repairs in short time. This stuff is really pretty easy, as long as everything is straight. It's just cables and pulleys.

I am truly amazed at the number of people who let someone else work on their bike.

I'm not talking about facing/chasing, but fairly simple, basic stuff. I have found that a few basic tools will really simplify things. I never assume that anything out of a box is straight, but a DAG pays for itself after two uses. Same with a FFG tool and a FAG tool, not to mention the FFS tool, which I've used to loosen lug nuts on a rusted Oldsmobile and break loose impossible fixed BB cups.

To have a Sachs and Campy 11s and rely on REI, or most other shops that don't speak 'Campagnolo' is a disservice to the bike and yourself.

In any case, wrenching is fun, if you are working on a Sachs with Campagnolo.

Take it from a guy who's worked on a lot of Schwinns

CSKeller · #15 07-18-2017, 09:16 PM

All of the above should help you. Campy is very easy to set up.

I'm sure you already know that and I'm sure you have done everything right but check this out just in case you missed something: https://www.campagnolo.com/US/en/Sup...ical_groupsets

Also, make sure you secured the cable on the rear derailleur on the correct side of the fixing bolt. If the cable is on the wrong side, it changes the geometry which affects the amount the derailleur moves for each click.

Hope you get is solved. Let us know what you find out.