I would like to add this tool to my kit. I see Parks carries 2 different ones and in fact I used both at different times while riding cross country last year.
Those of you in the know, which do you prefer?
Thanks!

A steel rule.

I've used both. The CC-2 is a little too fragile for my liking. You could bend it causing incorrect readings. The CC-3 go/no-go gauge is simple and sturdy.

However both only measure a very short distance on the chain. Unless you take multiple measurements on the chain, you could get a false positive or negative on the overall condition of the chain. That's why many people recommend using a 12" ruler.

I have the CC-3 and it is light, simple, sturdy and of limited reliability, as are all chain checkers that span a short length. It's better than nothing but the final arbiter of chain wear is the good quality 12" ruler.

I use a caliper How to Measure a Bicycle Chain

Park CC2. Very quick and easy to use. I can check chains on six bikes in my garage in one minute - I can do it without taking the bikes off the hanging hooks, I can do it in sub-optimal light, I can do it without putting on my reading glasses, I can take multiple readings quickly at different sections of chain without moving the crank. The tool errs a little on the high side, so if you really want to make sure you don't change your chain before it's reached the maximum recommended elongation, you can switch to a ruler after you get past 1% on the chain checker.

Chain tool threads are a common source of bickering in here - people who disagree with me are wrong.

Thanks RandomTroll!

I have the same caliper and I've been trying to figure out how to measure chain wear for ever!
I never could see any elongation of used chains using a steel rule. All my new and used used chains measure out to 12 inches exactly. I could tell they were elongated by how much slack was evident as they draped over the chainrings.

Thanks for the method!

Gram scale.

+1

You're really stuck on that chain weight thing, aren't you..?

I have a chain wear tool, I just never use it. Checking chain wear isn't something you should have to do every week or so and it isn't something that needs to be done super accurately either. A 12" metal ruler suits me fine.

If I decided to start using my chain checker again, the first thing that I would do would be to calibrate it against a brand new, never used chain.

Back in the olden days, the thumb rule was to lift the chain off the front of the chainring and if you could see the tips of the teeth it was time to re-chain.

I have used my Park CC-3 to test a brand new chain and, as expected, it shows no wear. Since it's a go/no go tool with only 0.75% and 1.0% elongation gauges it takes a fair bit of wear to show "failure". My 12" ruler allows much more subtle measurements.

KMC went digital KMC Digital Chain Wear Indicator - Modern Bike


thousandth of a gram.

That is probably the easiest way.

I did buy one of those digital chain calipers. It is a bit of a pain because it must be calibrated for every use, I think. But, technically it is accurate if one's calibration chain is good.

CC-3. With two points of reference, gives me and customers more than enough information to make chain replacement decisions.

I recently bought a CC-2 and I like that it gives a rough idea of the wear progression over time, rather than a strict "change it now" flag. My only difficulty is remembering whether the movable pin goes in the inner or outer links of the chain. Does it matter?

One pin is fatter than the other. I always put the fat pin in outer links which have a wider gap. I don't know if it makes any difference though.