Bicycle Mechanics - chain for Shimano IG cranks

I'm salvaging parts from an old bike.
The crankset looks okay, and would be an upgrade for my wife's bike which is showing its age. But it's got a label on it: "Shimano IG chain only".

A search tells me this is a part of the Shimano "Integrated Glide" system.
Since I won't be using any other IG parts (the other parts of the drivetrain would actually be Shimano Deore DX) are the crankset and chainrings actually incompatible with standard chains?

Shimano has overstated compatibility requirements for a long time. Just because the chainrings were designed for an IG chain doesn't mean that they won't work with another modern chain. You'd be fine with a Shimano HG chain. Better yet get a SRAM chain with special connector link so the chain can be removed by hand.

In Shimano's defense, IG chains were developed for indexed shifting and at the time of their development, common chains were fatter and had higher-profile plates that didn't shift as easily and wouldn't work well for indexing.

Shimano's IG90 chain should still be readily available and was the bargain of Shimano's line as they were sold by various mailorder sources for $15 or even less. I've been using them for years on 7 and 8-speed HG (nominally road) groups and they are durable and shift very well so I consider them a universal fit.

It seems like I've heard that chainrings intended for IG chains (and labeled as such) really do need an IG chain, and that a cassette or freewheel will be just fine with an IG chain even if the sprockets on the cassette or freewheel are "specced" for HG chains. I could be wrong about that, but I do know that I've got a mostly Alivio drivetrain on my wife's bike, and the Alivio crankset says "IG chains only" on it, so I'm running an IG chain but with a SRAM 8-speed cassette (presumably not necessarily designed for IG chains), and it works beautifully-

Don't you guys find the must replace with special pin everytime you break the chain fairly annoying?

Don't you guys find the must replace with special pin everytime you break the chain fairly annoying?

No, because I always clean and lube the chain on the bike so I never break the chain until it's time to replace it. It does work because I typically get 6000-7000 miles on a chain before the wear is far enough along to require replacement.

If you insist on removing the chain frequently, you can use a SRAM master link with Shimano chains.

If you insist on removing the chain frequently, you can use a SRAM master link with Shimano chains.

Interesting, I was worried about compatibility problems. Have you used this combo yourself?

So I'm curious, can you use an 8-sp chain on a 7-sp system? I was under the impression that you could not use 9 on 8 or 8 on 9.

So I'm curious, can you use an 8-sp chain on a 7-sp system? I was under the impression that you could not use 9 on 8 or 8 on 9.

7 or 8 speed will use the same chain, but a 9-speed chain is narrower.

Interesting, I was worried about compatibility problems. Have you used this combo yourself?
I'm currently using a Wipperman masterlink on my Ultegra 9-speed chain. No problems at all. Most manufacturers of chains and chain-stuff build to Shimano-compatible specs.