Thorn Cycles Forum
Technical => Transmission => Topic started by: rafiki on August 23, 2018, 05:58:57 pm
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Help, please. I fitted a new KMC X1 chain to my sterling this afternoon. It all went well. The fit is good, the slack is just as it should be. However, on riding out for a test the chain is very noisy under load. What could be causing this? What can I do to fix it? The chainring is 39T, the rear sprocket 16T. The chain has 96 links including the quicklink which is the same as the previous chain. Any help would be much appreciated.
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It sounds as if the chain isn’t meshing with the sprocket or chainring. This sometimes goes away very quickly once the chain flexes a bit. Were the sprocket and chain rings new? If not you could try reversing one or both of them.
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Thanks. No, neither sprocket is new. I will try reversing the chainring tomorrow. I don't have the tool for removing the rear sprocket.
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Brian,
Picking up from Geo's suggestion: Do the teeth on the sprocket and chainring look worn or hooked? If they are well worn, their pitch will no longer mesh exactly with the new chain, leading to problems such as noise and roughness. Reversing these as Geo' suggested would put new wear surfaces in contact with the chain rollers (provided it has not been done previously, or course ;) ).
There is one other possibility, however remote: When adjusting the eccentric to set chain tension, it is sometimes possible for it to slide sideways just enough to so the chainline is no longer spot-on. It might be worth checking to make sure the eccentric insert is centered in the frame's bracket hanger.
Best,
Dan.
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Hi Dan. Thanks for the suggestions. The teeth don't look badly worn. I recall my old derailleur chainrings resembling sharks fins at times. Nothing like that. I'll have a look at the EBB alignment. It shouldn't be too difficult to reverse the chainring but do you know of any way to remove the rear sprocket without the special tool?
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do you know of any way to remove the rear sprocket without the special tool?
Sadly, I don't...you need the remover to engage and steady the slots in the driver while you remove the sprocket by turning a chain whip or cog pliers left (all the while making sure the remover is held tightly in place by the hub's quick release).
This is yet another way the Rohloff differs from a derailleur setup: The remover is used to hold the driver still while a chain whip removes the cog. A freewheel is spun off by the remover. A more recent freehub cassette is held still by a chain whip while the remover spins off the lockring so you can pull the cassette stack off directly.
You can substitute a number of things for a chain whip, but the remover is pretty well required.*
Best,
Dan.
*I once removed a friend's _very_ worn Rohloff sprocket by using a tool I made, necessary 'cos the sprocket teeth were too worn to engage a chan whip very well. I just cut a "wrench" from plate steel and set some cylinder head socket head machine screws in tapped holes placed 'round the arc'd head. The screw heads engaged the holes in the sprocket and the cog came off easily. I wish I had kept it as it was easily among the most worn I've seen. Brian, if uou do change the sprocket, I would suggest upgrading to the splined sprocket and "slim" carrier ("slim" to preserve your present chain line as much as possible). The splined sprockets can be easily changed simply by using a flat screwdriver to pop off a circlip.
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Thanks Dan. I will get the chainring reversed tomorrow and check the EBB at the same time. Then, as geocycle intimates, give it a good run to see if every thing settles down. If not then a sprocket tool, splined sprocket and carrier on order from SJS.
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is the new chain well lubed ;)
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The chain came with a waxy lube on it. From reading elsewhere I was under the impression that further lube would not be necessary for a while. Perhaps I should lube it anyway and see if there is any improvement.
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Probably the rear sprocket. Reverse it or replace it with a new one, as others say the new type spline sprocket that fits on a threaded carrier is much easier to replace once you have got the old screw-fit sprocket off.
I wouldn't bother relubing the new chain, the waxy lube that comes with it should be good for a long time if you don't ride in wet or mucky conditions.
And in my experience, chainrings last longer than sprockets before causing chain problems, so I would only reverse the chainring if the drive is still rough AFTER replacing the sprocket.
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Thank you Martin. I was up very early this morning so I have already reversed the chainring. Having just returned from a short test ride it does sound like it is the rear sprocket. The overall noise level is a bit less and it is more obviously from the rear now so I guess there was a small contribution at least from the front. I shall now have to wait for the removal tool to arrive. In the meantime I think I'll revert to the old chain.
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I may be too late but if you need to loan the sprocket removal tool please pm me.
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I may be too late but if you need to loan the sprocket removal tool please pm me.
Thank you so much for the offer. That is very generous of you @geocycle. An hour ago I received notification of despatch from SJS of 1 removal tool. But thank you again.
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Hi,
I've the same noise problem after to have replaced my chain by a new one.
My chainring is a Surly 36 t (5000 kms), i tried to reverse it but it's still noisy. My sprocket is a 17 t (9000 kms) and already reversed at 5000 kms. Both looks in good condition.
I'm planning to ride like that with the parasitic noise because i'm currently traveling with my bike, however, do you think the noise will dissapear quickly ? or it's a risk for all my transmission to ride like that ?
For information, i replace my chain only, every the 4 to 5000 kms, do you think it is a good idea or useless ?
Thanks
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I did not have internet access for a couple of weeks when this thread started, only saw it now.
In the case of a sprocket with an even number of teeth (original post indicated 16T), I have heard that if you put a lot of wear on a sprocket with an even number of teeth, and then make a change so that the teeth that previously had the chain outer plate links now have the inner plate links, that it can be noisier. The theory is that every other tooth wears more as every other link elongates more as a chain wears. I am sure this is quite unclear, but this link might explain it better.
https://www.sheldonbrown.com/chain-life.html
I cut a small notch in one tooth on each of my chainrings and also on one tooth on my 16T sprocket. I am always careful to put a outer plate link on the teeth with a notch cut in the teeth.
This is unlikely to solve the problem for Julio with a 17T sprocket, but the original post cited a 16T sprocket, it may have been pertinent on that one.
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Julio,
I have a 36 x 17 chainring and sprocket on my Raven. The 36T ring is a Surly stainless-steel item. This past summer I had some chain noise for which I had difficulty finding the cause, and it was difficult to get rid of it. The chain was making a clickety-ripply metallic noise on the power stroke, especially on hills. (I'm not sure how much damage the noise would have caused, but I didn't like it.)
It appears that there was some incompatibility between the steel ring and my chain.
Currently, I am using an SRAM 971 chain on a new Surly 36T ring, and this appears to have solved the problem.
The 971 chain is slightly thinner (11/128ths inch) than the SRAM 830 and 870 chains, and the KMC X8.93 chains (all 3/32nds inch), which I had been using. (The difference is very slight, about .0008 -- eight thou -- of an inch. Can this make a significant difference? I guess it does.)
Here are the main points in what happened:
- My steel chainring had about 9500 kms on it, since I installed it in mid-2015. The teeth showed some wear, and the ring as a whole had become more oval. My local bike shop recommended changing the ring; I wanted to just reverse it, but agreed to replace it.
- The Canadian distributor had no Surly 36T rings in stock, so I used a 36T Sugino alloy ring for about 1,000 kms while we waited for the new Surly stainless ring. The chain noise was less, it but continued.
- When the Surly ring arrived, I changed the old chain (a KMC X8.93), which had about 4,500 kms on it. But, the noise was worse with the new KMC chain (!! ??)
- So, I took off the new KMC chain & installed an SRAM 870 chain. I checked and re-tightened the chainring bolts at the same time -- one had been very loose.
- The SRAM 870 chain at first seemed to have solved the problem. After about 150 kms, however, the noise came back :(
- In emails with Dan about the mystery, he mentioned that he uses an SRAM 971 on his Nomad. So, I bought one of those and installed it. So far, it seems to work -- the noise has disappeared.
Hope that's helpful, Julio -- good luck!
John
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John, you mention your ring had oval wear. Not exactly sure what you mean but I think you are saying that the part of the ring that is at the top and bottom when your crank arms are oriented fore and aft gets more wear, as that would make sense since that is when the tension on the chain would be greatest. If you still have the ring, you could turn it 90 degrees if your crank spider has four arms, or 72 degrees if it has five arms. That would spread the wear out a bit.
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George, I think I condensed things a bit too much, and created confusion: The guys at the shop said that the ring was "ovalized", and they thus thought that that was contributing to the problem. I took that to mean that the tight spot was unusually large, and it's true that the old Surly ring produced a noticeable and extended tight spot in the chain.
I wasn't too fussed about the tight spot (long acquaintance with British motorcycles), and would have just reversed the ring, had I been doing the work. Had I rotated the ring a fifth of a turn, though, would that have altered the tight spot?
In the event, having a pretty good rapport with the crew at the shop, I said to go ahead & swap out the ring. (When all was said & done, they didn't charge me for any of their time, because they couldn't find the source of the problem.)
It turned out that the temporary Sugino ring (a nicely machined alloy item) improved the tight spot considerably, so that the chain tension was quite a bit more constant than it had been with the much older Surly ring. But the chain noise, though reduced, was still present.
(I should have noted that the chainline was spot-on at 54 mm, except for being slightly off by .5 mm at one point of the circle.)
In the end, I'm still a bit puzzled by it all. I first thought that the problem was due to the wear on the teeth of the old ring -- looking at the ring from the right side, the rear "flanks" of each tooth had been flattened slightly, the first stage of indentation. But then, the rattly/clickety noise continued with the new Surly ring, and with different chains (SRAM 870 and KMC), disappearing only when I switched to the SRAM 971. Even there, I haven't been able to put on enough mileage this autumn to be sure that the problem has been fixed.
Cheers, John
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I think it is rare if you do not have a tight spot somewhere considering how easy it is for manufacturing to get a crank slightly off of being exactly concentric with the bottom bracket spindle axis. And there usually is a bit of slop in how well the chainrings fit on the chainring bolts, just as there is a bit of slop in how the chain ring bolts fit on the crank arms.
On my Nomad I have a very low budget crankset and low budget chainrings. Thus, I probably have more slop than typical in how things line up. I mentioned in a different recent thread (a Rohloff went for a swim) that:
When I put on a different chainring, I always backpedal the crank several times to see if the chain has a uniform amount of slack for the entire crank revolution. Sometimes the chainring is not quite concentric with the crank, and then I loosen the chainring bolts a bit and try to shift the ring position a bit on the spider and retighten the bolts to try it again. And when I have a reasonably consistent amount of slack, then I finish tightening the bolts.
Since I use a different chainring (44T) around home than when I am traveling (36T), I am changing chainrings much more frequently than I suspect most Rohloff owners are. Thus, I am reasonably practiced at trying to get the chainring concentric with the bottom bracket spindle axis.
I guess the bottom line would be that when you do any crank or chainring work, it is a good idea to check it by turning the crank backwards for half a dozen revolutions to check to make sure that the amount of slack does not vary too much.
And even then, by hard pedaling you might be able to shift the chainring on the crank spider by a bit later which could cause a tight spot to return.
If you are working on a Rohloff bike, it is my experience (limited to only my one Rohloff) that the hub is of a high enough precision that the rear sprocket will be very close to concentric with the rest of the hub. But on other IGH hubs that might have less precision, the hub might be slightly out of round and that could cause a tight spot too. I recall having some difficulties in that regard decades ago with some Sturmey Archer 3 speed hubs.
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Thanks for that useful tip, George. I'll try it next time -- I expect that there will be a next time!
I recall reading suggestions in other forums, on how to reduce a tight spot/get more equal chain slack (or tension). They were less gentle and elegant than yours--move the main tight-spot links close to the ring and give them a smart whack with a small hammer(!!) The intent was to move the ring ever so slightly on the square taper. I did try that--not without some anxiety--when I was running a 38T ring at the front, and it actually seemed to ease the tight spot (which wasn't all that serious with that ring anyway.)
I'll probably ride my Raven only when spring comes in a few months' time (late April), and before I do, I'll follow your advice.
All this seems quite distant as I write: we've had a dose of Saskatchewan weather the past couple of days, clear & cold and down to -10 or -12 C at night, -18 windchill. Tonight & tomorrow, we're due to have 20 cms of snow. Added to that, both of us have colds (now in retreat, thankfully) and I'm recovering from surgery on an arthritic left big toe--happily, that went well with an awkward bone spur removed and years and years of accumulated crud removed from the joint. Reckon I'll be able to get back to gym bef Christmas, though--certainly by the new year--and I'll take a bike when we visit our family Down Unda in March.
Cheers, John
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My crazy noise transmission has almost disapeared after to have ride 200-300 kms, only when i climb i can still hear it a little..
I think it's because my chainring is in stainless steel, that it was long to wait the noise disappears.
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That sounds good, Julio -- c'est à dire, not much sound at all! :)