Hello,
I have a question about 9 speed chains,I replaced my cassette and chain in March and now have 1900 miles on the chain and my Park chain checker shows .75 on the chain. The cassette was changed from a 11-32 to a 11-34 SPRAM.
The original chain was a KMC Z9000 it was replaced with another KMC but I don't know the number it was replaced by my LBS and this time I will replace the chain myself. How ever my question is this about right for mileage to replace the chain?I usually ride around 5000 miles a year. I know there is Shimano,SPRAM and KMC chains but which one would you recommend to use and is there really any difference in the chains them self? I clean and lube the chain and cassette at least once a week and always wipe down the chain when I get done riding I use Finish line dry lube in the red bottle and only apply a drop to each roller.The bicycle is a 2008 Fuji Touring Bike.
I appreciate all of your time and help.

https://www.bikeforums.net/archive/in.../t-558430.html

People have different opinions. Some say 2000 miles is the life expectancy.

replacing the chain extends the life expectancy of the cogs it passes over. , don't be attached to your chain.

Chain life will depend on your riding style and conditions. I've never used a chain checker but based on what I've read about their accuracy, I could probably eyeball a good chain better than those chain checkers could indicate one. Measuring across the rivets is a much more accurate method. 24 rivets should be exactly 12" on a new chain. If you don't want your new chain to skip, you should replace it before it hits 12 1/16". If you get to 12 1/8", you can be pretty much guaranteed that the new chain will skip on your most used cogs.

FWIW, I recently swapped a 9 speed KMC (not HMC) chain out after 4000 miles of use which measured 12 1/32". I'm keeping the chain and using a new chain which I'll remove at 12 1/32" stretch (hopefully another 4000 miles) at which point I might throw another chain in the rotation or go back to the original. I'll then let it stretch to 12 1/16" at which point I'll install another 12 1/32" chain. Eventually, all of the chains will be stretched past 12 1/16" at which point I'll be ready for a new cassette and chain. In my situation, I'm using a fairly expensive cassette so I'd like to try and get as much use out of it as possible before needing to replace it. The extra effort is well worth it.

Chain checking gauges tend to read high for a number of reasons which I won't bother going into. Measure your chain the reliable old fashioned way, as described by JoeJack above, and replace it if stretched beyond 1/16" over 12". The rate of cassette wear increases as the chain wears, so the per mile cost of running your drive train increases using old chains.

I'm not a fan of using a flat mileage basis, since the chain wear rate varies so much person to person, with some burning out chains in a little over 1,000 miles and others going for 5-10,000 miles. Everyone rides differently, under different conditions, and has different attitudes about chain care, so averages are meaningless to you're own situation.

BTW- follow good chain lube and care practice to maximize your chin life, and that'll save you dough on cassettes also.

Along that note. Once you've ridden consistently enough and o regular maintenance on your own stuff you get a rough idea on how long a chain should last. Whether it's one end of the typical mileage extreme or the other, or somewhere in between. Ini other words get to know your bike if you're intereste in taking care of it. Also chains wears in more than two ways. Lengthwise an 'width' wise across the rollers. A chain may measure fine but show and act like an extremely worn chain with roller wear.