I bought this tool after my shifts started to suffer. A quick check with the chain wear indicator tool showed that the chain was way beyond worn. I replaced the chain but the worn chain had worn out the cassette which skipped in several of the gears with the new chain. So I replaced the cassette also and it shifts like new. Spare yourself the cost of a new cassette, get this tool and check your chain often.
I finally broke down and purchased one of these. I usually replace my chain every 2000 miles. My current chain is approaching that mileage. I checked it with the CC-3.2 and discovered it is no way close to being worn out. I will save money in the long run.
Nice thing to have in your tool box.
Every cyclist needs to know when their chain needs replacing. This tool is an inexpensive tool to have in your box. There are other more costly tools, but I don't know why you would use them when this is more cost effective.
I relube my bike chains every 100 hrs. The bike shop had me replacing the chain annually but when measuring chain wear using this tool I discovered that the chains showed minimal wear ... I could never come close to engaging the 0.5% wear position. I've subsequently started doing my own bike maintenance and use this tool to ensure that my chain wear never becomes excessive.
It doesn't get any easier to use. Just slide it into the chain and you'll know instantly if your chain needs to be replaced or not. It has two sides one for really worn out and one for almost worn out which allows you to plan ahead.
Use this tool to see if your chain has stretched and is causing unnecessary wear on the more expensive parts of your drive train. This is made by Park, it's cheap, and it should be in your tool box or at close reach on your bench.
We have 8 bikes in the family, and I maintain them all. I used to check chain wear with a ruler, which was not very reliable and almost certainly resulted in some chains being replaced before they were worn out and others being replaced long after they should have been. With the Park CC-3.2, I checked all 8 chains in just a couple of minutes, and easily determined that 7 were good and one was completely worn out.