# Brand new bike - chain slip



## charlesbloom (Sep 11, 2004)

I just built up a brand new bike from scratch and I'm getting some chain slip. It happens when I accelerate really hard from a stop, the chain slips over a few teeth on the rear cog and then catches again. It doesn't happen every time. If someone told me that I would say the teeth must be worn or the chain stretched, but it's all new Ultegra matching parts.

It's possible the chain is too long by one pair of links, is that a likely culprit?

Another possibly related thing I've noticed is the spokes go "ting" once in a while from sliding/knocking against each other, I think they might be a tiny bit too loose (I didn't build the wheel).


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## Aussie Orca (Aug 11, 2009)

I'm sure I'll be corrected, but my experience with Human Powered Vehicles shows if the chains too long it'll slip. Pull a link out and see if it helps, be careful to not leave it too short for brain fades that end in big ring/big cog combos. All else fails, LBS are very helpful if you go in with cap in hand, and say "I don't know what I've done."


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## ServingTruth (Oct 2, 2009)

Chain length and a 1/4 turn on the barrel adjuster.


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## kidd546 (Nov 3, 2007)

Had the same problem on my wife's bike. The solution was to clean the chain in solvent and lubricate. Seems that the factory lube was too stiif and cause the chain to skip.


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## Mel Erickson (Feb 3, 2004)

Regarding the spoke ting. Common on a new bike where the spokes were not stress relieved (the case with all machine built wheels). Once settled in they will need touch up truing and possibly tensioning.


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## OES (Jan 23, 2002)

charlesbloom said:


> I just built up a brand new bike from scratch and I'm getting some chain slip. It happens when I accelerate really hard from a stop, the chain slips over a few teeth on the rear cog and then catches again. It doesn't happen every time. If someone told me that I would say the teeth must be worn or the chain stretched, but it's all new Ultegra matching parts.
> 
> It's possible the chain is too long by one pair of links, is that a likely culprit?
> 
> Another possibly related thing I've noticed is the spokes go "ting" once in a while from sliding/knocking against each other, I think they might be a tiny bit too loose (I didn't build the wheel).


Not to get WAY ahead of ourselves, but I had/have almost the same problem on a bike I built myself. After trying all the normal fixes on the differential diagnosis, I finally just put a new damn chain on. No dice. The cassette is new, and every tooth looks fine. I'm starting to think it's the freehub body.

But as I say, this is WAY down the diagnostic road.


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## C-40 (Feb 4, 2004)

*not chain length...*

Shift the bike into the little ring and smallest cog. If the chain does not hang loose or rub on the upper chain guide tab of the RD cage, it is not too long. Even a chain hanging a little loose will not skip. Removing 1 inch of chain will not help and may make the chain too short. Then the chain is trash, since you should never add back 1 inch of chain with any modern flush pin chain.

With true chain skip, the chain stays on the intended cog, but skips over the teeth under a heavy load. Most often, it only occurs on one or two cogs because they are worn out.
Chain skip does not mean moving over to the next smaller or larger cog. That's a shifting problem due to RD cable adjustment or hanger alignment.

It's not impossible for a new chain or a new cassette to have a defect that is causing the problem. To figure out which it might be, notice if the skipping is always on the same cog(s) or random. If it's random, I'd try another chain or at least check yours for a stiff link. A stiff link will definitely skip.


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## FBinNY (Jan 24, 2009)

+1 on C-40s analysis.

It is almost definitely not a chain length problem. Odds are it's a minor trim issue with the RD feeding the chain such that the plates hit the tops of the teeth, rather than being perfectly centered on each sprocket.

Use the cable adjuster barrel to fine tune the trim, to perfectly center the chain onto any middle sprocket. If it skips only on the smallest sprocket, use the "H" or outer limit to adjust the trim there. Better yet, since it's brand new let the seller check it out (should be no charge) and make this work properly. 

It's also likely that with a bit of break in the square edges on the sprockets will wear off making it less sensitive to trim and this will resolve itself.


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## livin4lax09 (Mar 15, 2008)

I used a friend's bike for a race because mine was waiting on replacement parts, and the chain was jumping like crazy. Eventually, I realized it was the chain length (when in small, small, it was dragging on the derailleur cage.) With all the jumping it actually tweaked the derailleur hanger as well, so it made it even worse. So check your trim, check your hangar, and check chain length.


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## Mel Erickson (Feb 3, 2004)

OES, what the heck you doin' in here?! Get back where you belong, interloper.


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## carveitup (Oct 25, 2008)

+1 on stiff link in chain.


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## Mr. Versatile (Nov 24, 2005)

I agree it could be a stiff link. Did you build the bike or did the LBS do it. It may not have the proper, or the best, chain for your component group.


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