Chainsuck problem

[CNY rider]

Here's what happened today with our triple tandem. Circa mid 90's Santana, I am not the original owner. It has an 8 speed Shimano triple drive chain (Biopace rings, remember those!).

Took the kids out for our first ride of the year.

Prior to the ride I had changed out the cassette and installed a new KMC 6/7/8 speed chain, as the rear shifting had somewhat degraded last fall. I had not had any chainsuck issues however.

Today the little ring was unusable. As soon as I shifted down to it, the chain stuck on the underside and jammed. This happened despite soft pedaling, on multiple attempts.

The front rings look worn to me and my guess is they need to be replaced, but is there anything else I should be looking at?

Thanks.

[bewheels]

Worn front rings play a big role in chain suck. The smaller the ring, the more easily they wear, and worn rings cause chain suck.

This is assuming you were not riding in the rain on dirt...another set up for chain suck. This situation also is ring related. Basically the chain is not releasing from the ring properly.

Small rings are cheap.

[CNY rider]

So as it turns out we were riding our local dirt roads to go to a pond and catch tadpoles, and it had rained all morning.
But I still think the rings are playing the biggest role.

[oldpotatoe]

Wornout chainrings get noisy but also 'hooked' and hang onto the chain when you try to shift off of them=chainsuck.

[Mark McM]

Wornout chainrings get noisy but also 'hooked' and hang onto the chain when you try to shift off of them=chainsuck.

And to add: A worn chain gets "stretched"*, with longer spacing between rollers, and the longer spacing can allow the rollers to slide out from those hooks. But a new chain will have shorter spacing between the rollers, so the rollers on an new chain can get caught on those hooks, causing chainsuck.

*Of course, chain links don't actually "stretch", but wear on the pivots can cause the distance between the rollers to increase, which lengthens the chain.

[AngryScientist]

make sure to check the rear hub too. if the hub is not coasting smoothly or there is too much resistance back there for whatever reason, that'll do it too...

[Vientomas]

New chains sometimes have a waxy coating on them that can make the chain stick to the chainring. Clean the waxy coating off and properly lube the chain.

[oldpotatoe]

New chains sometimes have a waxy coating on them that can make the chain stick to the chainring. Clean the waxy coating off and properly lube the chain.

uhh-oh..I see another 20-30 pages on 'should I clean a new chain'..A lot of the stuff is a rust inhibitor, since most chains end up where they are going via a ship but also a really good lube. I run any new chain through a rag with some WD-40 on it..not squeaky clean but some of the thicker goop, off.

[CNY rider]

And to add: A worn chain gets "stretched"*, with longer spacing between rollers, and the longer spacing can allow the rollers to slide out from those hooks. But a new chain will have shorter spacing between the rollers, so the rollers on an new chain can get caught on those hooks, causing chainsuck.

*Of course, chain links don't actually "stretch", but wear on the pivots can cause the distance between the rollers to increase, which lengthens the chain.

I'm pretty sure this is the problem.
Have ordered a new ring, will report back on the fix.