Chain vibration in model D with new parts

[Allan Olesen]

I have a model D1 where I have replaced chain, sprocket, chain pulleys and bungee.

I feel a slight vibration in the handle during both drive and recovery. The frequency seems to "match the sprocket teeth", meaning that I get one small bump every time a new tooth / chain link is engaged .

It is certainly better than before I replaced the parts, but it is still quite far from my experience from a new D2.

Could this be caused by the bearings? I did not replace those as they seemed fine.

Or is the chain sensitive to the type of oil used? I use some SAE 30 engine oil I happened to have in the garage. I know that C2 recommends SAE 20, but from the previous discussions on oil availability outside the USA, I got the impression that the exact quality was not that important.

Or is there a third possible reason I overlooked?

The bungees are adjusted to the correct tensioning, so I have ruled bungees out.

[Citroen]

Pick up the phone, call your local C2 representatives for advice.

[Carl Watts]

I would suspect a missing flywheel balance weight.

[Allan Olesen]

I would suspect a missing flywheel balance weight.

As I wrote, the vibration has much faster frequency than that. One vibration per chain link. And on the return it is linked to the speed of the chain, not the speed of the flywheel.

[Ergmeister]

I've run into this on a new (4 months old) C2 recently. It could be either the chain or sprocket. Do you feel a "clickity" sort of uneveness on the drive and recovery equally? If on recovery only, its likely the chain, and if both drive and recovery it's probably the sprocket.

The new "quiet" sprockets have plastic rings on the shoulders of each side of the sprocket. They are to quiet the chain as it contacts the sprocket's "barrel".

The plastic cushions can be black, orange, green, or yellow - I've seen all four. You could unknowingly be missing one or both sides of the sprocket's plastic so that the chain shoulder is in direct contact with sprocket barrel and that metal on metal contact point could cause some crunchy feeling which you are describing as vibration.

Take a bright flashlight, lift the chain up as it enters the plastic housing on the frame and illuminate the sprocket with the chain lifted up so you can see the shoulders and determine if the plastic ring on one or both sides is missing.

Because the quiet cushions on this sprocket are black, its very hard to see in the photo linked below, but the cushion on the right sideis missing and the one on the left side is slightly chewed up. This is one of the ones that gave me trouble and finally I determined that the quiet sprocket was chain on metal and that was vibration.
See photo here: -> https://photos.app.goo.gl/w6kFiTSmdKtH6pHZ6

[Allan Olesen]

I've run into this on a new (4 months old) C2 recently. It could be either the chain or sprocket. Do you feel a "clickity" sort of uneveness on the drive and recovery equally? If on recovery only, its likely the chain, and if both drive and recovery it's probably the sprocket.

The new "quiet" sprockets have plastic rings on the shoulders of each side of the sprocket. They are to quiet the chain as it contacts the sprocket's "barrel".

The plastic rings were my first suspect. On the old sprocket I replaced, they were brittle and broken. But on the new sprocket both plastic rings are intact. Luckily, they are easy to check, because they are almost neon green (I guess the same colour as in your photo).

I have the clickety feeling on both drive and return. It is not exactly the same feeling in both directions, but that is probably a consequence of the return being much slower than the drive.

Anyway, I found some 5W/30 multigrade motor oil, which is thinner at room temperature than the SAE 30 I have used until now. This has removed most of the vibration. I guess I can make it all go away if I lubricate the chain more thoroughly with this oil. So apparently, the viscosity of the oil is more important than I thought.

[Ergmeister]

Allan - while the oil is generally helpful, the chain itself might have an issue which I've also seen. The new nickel plated chains are good, but I've had some come through that were tighter than expected. It may be the chain too but the only to know on that is to change it. I would be careful about slathering up the chain with lots of oil as that tends to just fling all over the inside of the rollers and collect dust more readily.

If you pull the chain all the way out, stick a coat hanger or similar in the chain at the entry to the frame to hold it fully out, then let the chain rest on your hand with the handle dangling and run your hand back and forth and see if you notice any points in the chain where it is not falling over smoothly. Hard to explain this, but you are check the chain for tight spots in the assembly, or possible damage by observing how it rolls over from link to link as it turns the corner off your hand downward. The links should smoothly roll over your hand (or a broom handle or screwdriver shaft) as you move it up and down the slack chain with just the gravity weight of the handle. If the links are hanging a little before they fall over that could indicate the chain's the culprit.

I theorized that these are shipped in boxes of 50 or 100 chains and the ones on the bottom when the heavy box is dropped may be getting impacts in handling that pinches the links tighter together. I've seen this problem before too.

Rob

[Carl Watts]

Not had a problem with the nickel chains. Run them for a couple of sessions then put the Concept 2 oil on it. Really don't need a whole lot of oil, still got the oil that came with my Model C. The chain and sprocket gets better once "worn in" after a few hours of use. It should get to the point you cannot feel any feedback in the chain to the handle in terms of the chain links running over the sprocket. The model D setup is far smoother than the older Model C, you can feel every link. I could convert my model C but want to keep it original as a reference.