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Skipping chain problem on Ultegra/triple setup(4 posts)

Skipping chain problem on Ultegra/triple setupPeterRider
Jul 25, 2002 1:29 PM
I just put together a bike with Ultegra triple setup, and I got already several times the chain skipping from I think 4th cog to 3rd, maybe also 5 to 4, when I pushed hard on the pedals.
- the chain is in good condition, I checked the wear with the park tool thing, it says between .25 and .5, which seems to be normal. I got it used, the guy said less than 500 miles and the park tool indication seems to confirm.
- I got the derailleur from the same guy, it seemed in good condition and not much wear on the pulleys.
- the cassette is a dura ace 12-27, so the cogs in question are 14-15-16. It has about 1800 miles on it. I took it apart yesterday evening, the said cogs look good.
- the right shifter is a brand new dura ace.

So my hypothesis are:
- small "B" screw of the derailleur not tight enough ?
- derailleur cable too loose and helping chain skipping ? The derailleur is shifting fine though.
- too much lube on the chain ?
- chain too long ?

Any suggestion ? Thanks in advance,

re: Skipping chain problem on Ultegra/triple setupChen2
Jul 25, 2002 2:32 PM
My best guess is you need more cable tension, or the chain may be too long. Shift the derailleur to the smallest cog, and a couple of extra shifts with the small lever to assure that the cable is all of the way out. Turn the barrel adjustor all of the way in (clock-wise). Loosen the cable retaining screw and pull all of the slack out, then re-tighten the retaining screw. You can then apply more tension as needed using the barrel adjustor, increasing is counter-clockwise. Try shifting through all of the cogs, there should be one shift for each cog. If you have too much tension you won't be able to shift to the smallest cog. If you don't have enough tension the chain will hesitate or not shift to the larger cog(s).

Check the chain length- with the chain on the smallest chain ring and smallest cog the derailleur should be applying some pressure to the chain. The chain should not be hanging loose. You should have a triple rear derailleur (long cage). You should also have enough chain to be able to shift into the big - big combination.
re: Skipping chain problem on Ultegra/triple setupcurlybike
Jul 25, 2002 3:03 PM
I suggest that your chain is more worn than your cogs. The chain should be less than 12 1/16 inches long over any given 24 links, measure from the edge of a pin to the edge of a pin about 12 inches away. If it exceeds 12 1/16 you can expect it to skip. This method seems to be more reliable than any gauge being sold.
If the chain is between .25 and .5" :Alexx
Jul 25, 2002 3:47 PM
then, it is WAAAAY past time for replacement. A chain should be replaced when it is 1/16" elongated, which is .0625" elongation. As a result, the cogs have also been worn improperly, and all are now junk. You usually can't tell if cogs are OK just by looking, unless you REALLY know how to. Also, D/A cogs wear very quickly-they were probably junk at about 1000 miles. You've been ripped-off, by the sound of it...
Caveat Emptor!