CaptainPlanet

And durability wise, are they better or worse than surface-rusted steel cassettes? Not a lot of information to go with because I don't have cassette removal tool to take them off the wheel. I also screwed up and didn't focus the camera when I took this pic.

Tony P.

Plating is probably nickel for corrosion resistance but underlying material is often steel or aluminum.

Bill Kapaun

And magnets are impossible to get.

dsbrantjr

+1 very likely nickel with a copper underplate for adhesion, as nickel does not adhere well to either aluminum or steel.
If chrome it is almost certainly copper, then nickel as a barrier layer (chrome will react with the copper) and chrome on top of that.

CaptainPlanet

Ah, I do have an abundance of magnets sitting around. Will give that a try.

Miele Man

I have a couple of old Shimano N600 freewheels with plated-cogs that are silver in colour. They are form the mid 1980s and the plating is still solid as is t he plating on my silver colour Uniglide cassette cogs.

2_i 

Good cogs are made of tool-level hard steel. Plating will rub off on the teeth if they work. You have to apply protection no matter whether you start plated or not. The only practical reason for going with plating is that it is likely to correlate with the overall amount of effort going into the manufacturing.

CaptainPlanet

So I have confirmed that it is indeed steel by doing the magnet test

The reason I made the thread is to figure out if this cassette which has extra holes carved out for weight reduction is as durable as my other cassette which doesn't have weight reduction in design and has started rusting because it was left outside for a while. I wont to figure out which ones I should use for my main bike.

I had thought the silver one is worse because it may not be steel, but turns out it is steel. The other set has already started rusting, and rust can cause friction and furthering wear.

dabac

Cassette rust is mainly cosmetic.
It’ll wear off in minutes from the flanks on the teeth.

FastJake

Rust on a cassette isn't a problem. The places where the chain contacts the teeth are constantly "polished" (worn) by the chain. And since the chain should be lubed, those areas won't get or stay rusty. A nickel plated cassette might resist rust better than a black painted one, but it doesn't really matter. Clean the cassette if you want and call it a day.

Virtually all cassettes are made from hard steel. Some very expensive ones will have titanium larger cogs to save weight, not to improve durability. And some "event" cassettes were made from aluminum to save even more weight, but they wear out almost immediately.

robertorolfo

I spent the summer before my senior year in high school doing an internship at a chemicals company, running experiments on electroless nickel plating. Unfortunately I can't remember too much about it, but it was pretty interesting and I think it's used a lot in the automotive industry.

dsbrantjr

Electroless nickel, as you know, leaves a layer of nickel-phosphorus (or less commonly nickel-boron) alloy which is quite porous and does not have the rust resistance of plated nickel so it is used for stuff like trim or for wear resistance on internal parts.
My experience was in the semiconductor industry so very pure plating layers were required; the phosphorus or boron would have "doped" the silicon or gallium semiconductors. Better than 99.999% ("five nines plus") purity was the norm.