Chain running rough: 130mm in a 126mm

[weaponsgrade]

I've got a 126mm spaced rear drop-out (steel frame). I can squeeze a 130mm wheel in there, but the chain runs a little rough in the small cog.

I do have a 126mm rear wheel that runs fine. It was originally 130mm and is an old Campy wheel with the threaded axle. I was able to remove some spacers to make it 126mm.

The reason I want to run the 130mm wheel is because it's a Shimano freehub and I've got 32T cassette I want to use. The 130mm wheel has a White Industries H2 hub.

I held a straight edge against the rear derailleur hanger (with the RD removed) with the 130mm wheel installed and then the 126mm wheel installed. I think what's happening is that the rear derailleur hanger is off by what looks to be just a few fractions of a millimeter with the 130mm wheel.

I really don't want to cold-set the frame. Does anybody have any other ideas or hacks?

[Ken Robb]

might you be running 7/8 speed chain and 9/10 speed cogs?

[weaponsgrade]

It’s actually the reverse: 8 speed cassette and 9 speed chain.

[Ken Robb]

That's what I should have asked. So, isn't a 9 speed chain narrower than an 8 speed chain and might it therefore grind a little at the extreme angle at the end of the cassette?

[ultraman6970]

1st thing... put a 10 speed chain in there, cheaper.

2nd thing, areyou sure is not the chain the one touching the dropout/chainstay area? if it does see if a 10 speed chain fix it, if not buy a really nice file because u might need to make space for the smaller cog.

What i think it happens is that the joint area between the stat and the dropout is set up for 6 cogs era, so that area in question is thicker, you put a wider cassette the lockring and the chain might be touching the area in question.

[11.4]

You could have a variety of things going on here. First, you don't say whether it's grinding from the chain rubbing on a large chainring/cassette cog/left seat stay or just noise. You also didn't indicate whether it's a problem in the small chainring only, or in both.

Here are some of the options:

1. In that cog it just might be rubbing on the inside of the seat stay.
2. It might be rubbing against the inside of the large chainring if it's only a problem in the small chainring.
3. Your chainline might be bad. The chainline might have been straightened out with your 126 mm wheel if you took out spacers that evened out the chainline rather than just taking off 2 mm on each side evenly.
4. Your chain stay might be too short so the chain is just having to make a bend in too short a distance (again, assuming small chainring only). Not too likely with a 9-speed chain.
5. You suggested your rear derailleur hangar might be off. The only issue is, it should be adjustable to accommodate whatever cogs you have on the rear; chainline issues would be resolved by readjusting with regards to the chainrings.
6. Some small cogs are just noisy -- the chain can sit on the base of the cog between the first and second cog rather than in the gullet of the cog itself. Plus some small cogs are small enough that the extra chain link rotation requires more movement and thus more noise.
7. Your old wheel may have a cassette (or freewheel?) with different shaped cogs or a cog with a different number of teeth; at that point you've introduced a lot of new variables.
8. You may not have enough tension on the chain, so when you finally get to the small cog it doesn't seat smoothly on the cog; the noise could be in the derailleur or in the cog itself or almost anywhere.
9. The rear derailleur cage itself could be out of alignment and you accentuate the issue when you get to the small cog. At that point the chain is scraping against some part of the derailleur cage or possibly just riding up on the jockey wheels a bit.
10. Is the chain worn? Or the cog? Small cogs can often accentuate the noise of misfitting chains and cogs due to wear.
11. And the possible reasons go on.

I wouldn't worry about resetting your frame. I wouldn't lay blame, with a 9-speed chain, to the tiny bit of alignment issue. I'm betting on #8 or #9, unless the problem lies with a difficult cog (which you can check by putting on a cassette with the same number of teeth but from a different manufacturer or different grade (e.g., Ultegra vs. Dura Ace)).

[oldpotatoe]

Originally Posted by weaponsgrade

I've got a 126mm spaced rear drop-out (steel frame). I can squeeze a 130mm wheel in there, but the chain runs a little rough in the small cog.

I do have a 126mm rear wheel that runs fine. It was originally 130mm and is an old Campy wheel with the threaded axle. I was able to remove some spacers to make it 126mm.

The reason I want to run the 130mm wheel is because it's a Shimano freehub and I've got 32T cassette I want to use. The 130mm wheel has a White Industries H2 hub.

I held a straight edge against the rear derailleur hanger (with the RD removed) with the 130mm wheel installed and then the 126mm wheel installed. I think what's happening is that the rear derailleur hanger is off by what looks to be just a few fractions of a millimeter with the 130mm wheel.

I really don't want to cold-set the frame. Does anybody have any other ideas or hacks?

When you spread the rear dropouts out, you also make the dropouts and der hanger, not parallel to the cogset/cogs..tightening down the QR helps some but still may have alignment issues..

Cold set it liazza, cold set it.

[oldpotatoe]

Originally Posted by ultraman6970

1st thing... put a 10 speed chain in there, cheaper.

2nd thing, areyou sure is not the chain the one touching the dropout/chainstay area? if it does see if a 10 speed chain fix it, if not buy a really nice file because u might need to make space for the smaller cog.

What i think it happens is that the joint area between the stat and the dropout is set up for 6 cogs era, so that area in question is thicker, you put a wider cassette the lockring and the chain might be touching the area in question.

1st thing..10s chains aren't cheaper than 9s or 8s chains.
2nd thing..8s cogset and index/click shifting, and a 10s chain, which is MUCH narrower, chances are it won't shift at all..index shifting requires a certain width chain as the next cog is actually 'grabbing' the chain and shifting it..to narrow and it won't shift.

[palincss]

Originally Posted by ultraman6970

1st thing... put a 10 speed chain in there, cheaper.

Where do you find a 10 speed chain cheaper than either an 8 or 9 speed chain? Everywhere I look, it's exactly the opposite.

[ultraman6970]

uk

Ive used 10 speed indexed in 8 speed drivetrains... dunno whats the problem, I would not do it in a 6 or less tho... 7? dont remember trying.

[weaponsgrade]

Thanks for the all the responses. The chain is clearing everything. The dropout faces are parallel (when checked without any wheel mounted) but as OP noted I think things are getting a little out of plane when I squeeze in the 130mm wheel.

The chain is a used 9 speed Campy chain and the cassette is new. The chain still looks in good condition as I don't measure any noticeable chain wear using a ruler. The RD is also in excellent condition. The derailleur cage checks out fine using a straight edge.

What's happening is that the chain rides up the little cog when I'm spinning the cranks in the stand. This happens regardless of whether the chain is on the inner chain ring or outer chain ring. There aren't any stiff links. The chain's been sitting in a bag for a long time and could use some lube, but I'm trying to get things running straight first.

I tried adjusting the limit screw while spinning the cranks and I just can't find that sweet spot. The chain either goes off the little cog or wants to climb to the next cog.

The Shimano cassette has an 11T cog and the Campy cassette (on the 126mm spaced wheel) has a 13T cog. The points about smaller cogs having that extra chain link rotation and chain tension sound interesting. I haven't cabled anything up yet, but when I push the RD by hand into the next cog and hold it there while I turn the cranks - everything seems to run fine.

I set the chain length with the chain on the small-small combination. So, the chain is tensioned, but there isn't a whole lot of tension. I'm going to try removing some links to up the chain tension and if that doesn't work a new chain. I've got a new spare chain I can try.

[11.4]

Eleven-tooth cogs do tend to be noisy, especially on the stand. You don't notice it as much on the road, partly because you should be going pretty fast to be in an eleven.

Spud makes the point that you may have altered your rear end alignment so the rear derailleur isn't really positioned correctly. If you space out a rear end alignment tool to 130 mm and check that the stay ends are in alignment, that'll rule out one issue.

Mostly, don't expect cross-chaining to an eleven to be quiet. And it'll be a lot worse if you don't have proper chain tension on it.

[Ralph]

New chain, old chin, partially worn chain? New cogs, worn cogs, slightly worn cogs? From what you describe....I would be surprised if it ran quiet. It might "wear" in after some miles.

[dddd]

^^^^^...sorta what I was thinking, especially if the old chain was broken in and used on a cassette with a 13t smallest cog.

With the chain seen to be "riding up" the teeth of the small cog, assuming that engagement is actually occurring at the point where the chain feeds onto the cog, the chain should not be able to ride up the teeth unless is is well-stretched.
If the chain is riding up the teeth at the point where it is feeding onto the small cog (i.e. at the downward point), then the derailer is somehow not positioning the chain directly in line with the cog and so may be beyond it's travel limit(?).
In which case, perhaps a shim washer under the mounting bolt will allow the chain to feed onto the small cog with hi-limit adjustment available in either direction.

[weaponsgrade]

Update: I finally got everything working - sort of. I installed a brand new chain (kmc 10 speed). So, that's a new chain and new cassette. That didn't work. I tried installing the drive side crank so the chainline would be biased towards the little cog, and shortening the chain to increase tension, and the chain was still jumping on the final 11t cog. I then took out the 11T cog so that my final small cog is a 12T. Everything is now smooth and quiet with that 11T cog out. I put a spacer behind the cassette. The low gear limit screw on the RD wasn't long enough to limit the travel so that the chain wouldn't get thrown off between the spokes and cassette. However, I was able to gain a few more turns by removing the spring from the limit screw and that was enough to prevent the RD from throwing off the chain. The cassette lock ring interfaces with a cog surface that's smooth but hopefully that won't be a problem.