I lost track of wear on my Terry's chain and it is very, very worn. I assume the cassette is very worn as well, I have never replaced it. I bought the bike used and maybe put 6000 miles on it. How long can I go along this way before I harm my chain rings on my crank? How will I know if I have worn out those as well?

This bike is a steel bike and a nine speed on the rear with a triple on the front. Does it matter what level of cassette to get? Does going cheap matter? I use this bike like a hybrid, riding it around towns, geting groceries, etc. and it has has on a rack exposed to weather as I drive all over the USA.

The first mile damages the rings. It's called wear. It just happens at a slower rate then rear cogs. You need to have some one with experience look at the rings, or just replace the chain and rear cogs and see what happens. Andy.

in a perfect world, i wait for the chain to start skipping before i get a new one, but it seems like, for some reason or another, i'm always replacing them long before that happens. i think that switching from 3/32" to 1/8" cogs and chainrings and occasionally throwing on a rear derailleur has something to do with it. that and the fact that they are pretty inexpensive.

Unfortunately I don't have all the answers, but here is my analysis.

The chain is spaced for the pins at ˝".

If a tooth on your cassette wears uniformly, then the spacing will remain at ˝". A longer chain wouldn't necessarily dig deeper into the cassette (where spacing is shorter), but might ride a bit higher, and thus add a bit more angle to the bottom of the tooth, and narrow the top of the tooth.

As the chain wears, however, much of the pressure gets transferred to the last tooth on the cassette or chainring, with the chain essentially slack over the rest of the teeth.

The good thing about the cassette is that it rotates in relation to your crank stroke, so it will wear uniformly.

I did manage to prematurely wear out one of my chain rings by allowing the chain to stretch too much. It was the 42T chainring. The 54 is worn, but hasn't caused me a problem. With the 42, I would tend to stand while pedalling, so I had an uneven stroke. This meant I ended up with more wear during the power phase of the stroke than the top/bottom of the stroke. With the replacement chain, it made a lot of noise, but otherwise worked.

A couple of chains back also tarted breaking after too much wear, which was frustrating.

Anyway, go ahead and replace the chain, then see how the bike rides before replacing more parts. You'll notice either increased drivetrain noise, or skipping.

Some report getting more mileage than you've gone and not having any problems.

Most people notice they have a worn chain when it starts to skip, usually under heavier pedaling.

Replacing the chain when worn will save the sprockets and chainrings although the chainrings (in front) are usually the last to wear.

The conventional way to measure chain wear is to measure the distance between 25 pins while the chain is stretched out. A new chain should be exactly 12" long because each link is 1/2". A stretched (actually, it's wear, not stretch) chain will be longer. IIRC you don't want it stretching more than 1/8".

Keeping a chain clean seems to help some but others swear it's enough to oil each roller and then wipe off the excess oil because the oil takes a path that supposedly flushes fine grit out to the sideplates when you oil the roller. (except with really old chains on vintage bikes because they're put together different.)

Cassettes are at most prices Cogs are steel .. its surface finish to make it shiny that costs more .
so there ya go .. chrome plating is just for looks .. if the chain stays oiled there will be some on the cassette..

You might have someone sew a Cover for your bikes on the Back of your MH.

Hard chrome is a durable wear resistant surface. It wouldn't surprise me if it can extend the life of a cassette just a little bit.

''

Chrome is still softer then oxides/grit. Andy.

I buy cheap Shimano cassette, but swap between a couple of them often, depending on time of the year or vacation.
I basically run 12-23 during Summer, 13-25 during Winter and toss on the 11-34 when i go on vacation in my hilly hometown.

First of all, you have time to decide since odds are that the cassette is shot (if the chain stretch = 1% or so), so there's nothing to lose back there.

Chainring wear happens at a glacial pace, even with a worn chain, so fee free to consider where you want to go from here.

If you replace the chain and cassette (of necessary), the odds greatly favor the rings being fine. So that would be Plan-A, and waiting a short while won't change anything much.

OTOH- id the chain is now well beyond 1% stretch (it shouldn't be, but measure) The rings may have suffered a bit, and you might consider Plan-B which is to keep the existing drivetrain as is until the chain skips on the current cassette (usually at 2-3% stretch), but then you'd also be replacing the rings. I generally reserve Plan-B for when I know things are already pretty bad, like after replacing a few chains and two cassettes.

Know that chainrings are far more forgiving of wear than are the cassette sprockets. I have rings still going strong with teeth worn about halfway across their root width. So don't feel obligated to replace them before it's necessary.