That is the question...

I just bought a new chain because my old one kept slipping and it sounded/felt awful. I put the new one on and I'm wondering what the point of having a masterlink is. I put it on without one and everything seems fine.

So questions:

What's the point of them?
Are they safer?

They're quicker and easier. A lot of mechanics I've spoken too won't use them in high tension situations like single speeds but they're fine with derailleurs. Preference I suppose.

I'm having a little trouble with your question and The_Joe answer. Generally bicycle chains are designed around a way to join them. Some come with "master" or snap rings and some come with special pins. Chains today rarely allow you to press out a pin, put the chain ends together and then press the pin back in. If your talking about using an aftermarket link they usually work very well. I normally use whatever the system is that comes with the chain. Single Speed chains usually come with master links that are of equal strength of the rest of the chain; if your source says not to use a master link with a SS chain, how are you supposed to connect the ends?

I've always used master links until a few weeks ago when I just converted to SS. I had a pro do a once over and he said he doesn't lie master links because of the safety. He measured the chain to length and pressed a pin back into it. No harm done to the links. Isn't that a common practice?
Many people on this forum are leaps and bounds more educated than myself on the subject. My apologies if I left an answer that was detrimental.

Depends on what kind of drivetrain you're running. 9+ speeds, I always prefer to use a master link over breakaway pins. For the rest, if it's included, I'll use it. but I find it to be more hassle with a single speed chain. I think they're great for the most part. I would always recommend a master link when people ask me at the shop, and I've heard people curse about them too, but then realized they just don't know how to use them properly.

If nothing else they help you keep a reference point for lubing your chain...

Only protruding-pin chains can be joined by pushing a pin most of the way out, then pushing it back in, once the two ends are joined. Most modern chains are flush-pin chains. Those pins are basically flush with the outer plates and rely on heavy peening of the pin ends to keep the chain together. If you push one of those pins out, it will actually shear off a small ring of metal, leaving one end of the pin with no holding power.

Are Master Links available for 11 speed chains?

As per DaveSSS's posting, if the chain he uses are 1/8" Track type or older design 3/32" derailleur chains with wider, protruding pins, then reusing the same pin to join the chain is fine. Modern narrow (8-speed and higher) chains must not have a removed pin reused.

KMC makes 11-speed chains that come with a master links. I don't know if the links are available separately.

What's wrong with a master link on a SS ?

Yes

https://www.probikekit.com/us/kmc-mis...-11-speed.html

I use SRAM chains with Powerlinks on my FG. I see no reason not to trust the Powerlink as much as any other link in the chain.

I have never had an issue with them, even on single speed and fixed gear. I'm not a mash-monster, though. Certainly I see no issue with using them in normal applications.

Learning something new every day.

Indeed. Most vintage single speed and IGH bikes use chains with master links.

Jess does not make clear, is he talking about a derailleur, multi gear drive train,
or a single speed /fixie/IGH..

have a specific chain in mind, Jess ?

Does it really matter ? As long as the link is compatible with the chain (10 speed link w/ 10 speed chain ...)
As stated, they are more convenient, and could be safer compared to a botched job with a chain tool & pin.

With a name like "Fixed-drive Jess", I would presume a FG application. But then, I can't see how a chain could ever slip on one of those.

The granny gears on MTBs and touring bikes will put way more tension on the chain than the typical single-speed. I think the people most concerned about chain failure are the brakeless riders, but any decent chain should be strong enough in a straight line for them.

In my opinion, on SS chains using a chain tool to press the link together is a more secure connection, especially in high torque situations like a fixed gear. Over my 25+ years of shop experience I have surely seen more master links fail than (properly) pressed together links. While we are on the subject of master links, I have always installed the retaining clip with the closed end facing the direction of rotation...do all of you experts agree with that bit of bicycle mechanic minutiae?

That's what KMC says to do: https://www.kmcchain.us/ChainGuidePDF...structions.pdf

I'm curious and always willing to learn -- which connectors failed the most, and how did they fail?

The ONLY chain failure I have ever experienced was due to a &%$#(@! master link failure.
I actually heard the darn thing skitter across the pavement into the bushes, in the dark. No chain tool with me and it is also the only time I had to make "The Call Of Shame" for my wife to come pick me up half way home on my commute.

I've been riding a SS in the mountains (ie very high torque) for about 8 years now and have always used a master link. Never had a problem or failure. I change my chain every year and keep it clean and lubed.

Both my bent and my trike has master links on them. The bike has 10,000 miles with no problem. What I like is the chain can be easily taken of to clean both it and the drive train. Add that that a lot of new chains dont like to have their pin messed with.

Master links for current 8,9, 10 and 11-speed derailleur chains do not have an "open end". You are describing the master links used on old style bike chains and motorcycle and insustrial chains.

I too have never had a modern bike master link fail and I've used Forester, SRAM and Wippermann links extensively on 8, 9 and 10-speed chains. The 8-speed Forester links did develop a clicking sound after some use but never failed.

In the 80's the Sedis-Sport chains had no master links,they were early
in the making of bushingless chains that dominate the derailleur chain market
for type..

I never used any master links , none were made outside of 1/8" chains .

rode several International self contained bike tours, months long,
on those chains , old gear, friction bar con levers
and 6 or 7 speed freewheels .. never broke a chain ..

Maybe some of knowing how to use the chain tool,
some in not forcing shifts in hard climbs,

Or maybe I was just slow and enjoying the trip and not abusing my bike..
or knees and so forth..