Model C - chain catching anti-throw device (PN 1002)

[Wioslaw]

A week ago while rowing on my Model C i heard a popping sound coming from somewhere around the sprocket, happened maybe 2 or 3 times.
Today I heard it again on harder pull and I noticed that it is the chain catching on anti-throw device (PN 1002 on parts diagram). The chain is old but I does not have any frozen links.
Is it possible that the sprocket is worn out so much that it's outer diameter has dropped and the chain is now too close to the "anti-throw device" ? I have checked the rubber bearing cups and they seem to be fine (there is no play) and also the axle does not move on hard pulls.

[Cyclist2]

I just looked at my model C. That plastic part is worn on the bottom edge from the chain sliding over it. I can't see any way it can catch on the top or sides.

Has the anti throw device been dislodged? Is your chain catching on the bottom? I doubt the sprocket has worn that much - it would be visibly worn at that point and probably causing worse problems. Since it is just a plastic part, I would take it off and file the edge that is catching down (the chain will still retain it but the filings won't drop down into the enclosure), and then reinstall it making sure it is centered. Make sure your chain is lubed properly and check for anything that might protrude to catch the plastic (debris, damage, etc.).

[Wioslaw]

The bottom edge is worn out a bit but it also has a couple of fresh scratches. But the top edge is also scratched. Since the plastic part looks non critical I think I'll remove it for a while just to see if there will be any difference.
I have inspected the chain link by link on the day I bought the machine and it does not have any visible damage. All links move freely, but perhaps there is one that locks up under heavier load.

[Wioslaw]

It turns out that the plastic part is not guilty. I think that there is a section of the chain that is worn out more than rest of it and it jumps on the sprocket. Today I got it to pop with the PN 1002 removed by doing a couple of quick accelerations starting from the flywheel completely stopped.
Just to be sure I used white paint to mark the axle and one of the links with dots, after next pop I'll check their relative position.

Does the nickel chain fit the model C sprocket ? I was going to change it anyway. Our local distributor told me that I have to buy the new sprocket and axle to use model D chain.

[Allan Olesen]

Does the nickel chain fit the model C sprocket ? I was going to change it anyway. Our local distributor told me that I have to buy the new sprocket and axle to use model D chain.

You can buy a silencing kit for model C, consisting of a nickel chain and a sprocket, probably similar to those used in the model D. So even if you don't think the sprocket is worn, you might want to do it just for the noise reduction.

[Wioslaw]

The problem is that for someone living in Poland these parts are not cheap. They aren't very expensive either but I'd prefer to buy the chain first and the sprocket with axle in a month or two, but I don't know if the new nickel chain works with model C sprocket.
I was going to upgrade to the silent kit anyway, as I row in my living room and the original model C parts are quite noisy.

[rakserv]

the nickel chain will work fine with the old sprocket, however it is recommended that both sprocket and the chain be replaced at the same time so that they break in and wear together.
https://www.concept2.com/service/indoor ... n-problems

the newer sprocket is slightly different physically than the model c sprocket, so when threaded onto an old model c axle it won’t properly align itself and therefore the chain to the center of the chain guard.

I replaced a chain, axle, and sprocket on a model c and it started slipping/clicking on the drive.
https://m.youtube.com/watch?v=nylOVDrrW ... e=youtu.be

I ended up replacing the axle and sprocket and it fixed the noise and slipping.

[Wioslaw]

I'll order the complete silent kit with a new chain in a month or two. For now I increased the bungee cord tension a bit, as I did not know there is recommended tension range when I replaced it, and it fixed the problem.
The chain was definitely skipping one tooth on each pop - the distance between my marks was increasing - and the sound came from the chain hitting the plastic part.