Bad link in chain?
 

https://cimg7.ibsrv.net/gimg/bikefor...82fc24dfcc.jpg
I just bought a used bike that has a skipping chain. This link in the photo is very stiff, it won't bend easily there and that is when it skips.

New chain needed? Can I replace that link? This is on a 1984 Trek with a 6 speed triple.

Thanks!

Before replacing it, get a chain tool and try to make the link more flexible by forcing the pin deeper into the side plates so the link will flex more.

Just grab the chain on each side with your thumbs on each side of the bad link and bend in both directions the way it DOESN'T want to bend.
You can usually loosen them up quickly. Just don't overdo it. It will take a "few" pounds of force.

The black link looks like it was spliced in at some point. It's possible whoever did it didn't ensure the link was freely moving. [MENTION=78399]Bill Kapaun[/MENTION]'s advice is sound; flex the chain sideways at that link and it should free up.

If it doesn't, you may be able to replace it with a master link, but it's possible a modern master link might not fit that vintage 1980s SedisSport chain. If that's the case, a new chain, and likely a new cluster will be needed. Try the simple fixes first.

Just change the chain. They are cheap enough.

Thanks guys! Just flexing it helped some. Maybe now getting it off and cleaning and lubing it will do the trick.

Flex it more, or as suggested, loosen it with a chain tool.

That looks like a non-peened-pin chain link spliced in to a peened-pin chain. For a 6 speed, I would source and install a new non-peened-pin chain.

However, if the current chain is very worn, the cogs will likely be worn to match and the chain might skip violently under load.

Thanks! I flexed it a lot, and cleaned dry lubed that one link repeatedly. It is still just a little bit stiff, but is working fine with no skipping now.