jays35

Went out for a ride this morning, 2 miles into my ride, the chain broke.

I oil and check my chains before every ride and did not see any issues when I wiped it down. I also use the one of my Park chain gauges (CC-3.2 and the CC-2) about once a month to check the chains on my bikes. This chain has about 1500 miles on it and has checked within tolerance each time.

So, when I got back to my shop and checked the chain, one gauge said good and the other was bad. The CC-3.2 showed that it was good, but the CC-2 showed it to be bad. I did check the same section of chain. Note: The pins on the CC-2 are not bent.

My next check was to measure the distance between the pins on the CC-2 and below are those measurements.

4.620” @ 0
4.629” @ .25
4.730” @ .50
4.739” @ .75
4.759” @ 1.0

Looking at these measurements……
the delta between .25 and .50 is .101”.
the deta between .50 and .75 is .009.
the delta between .75 and 1.0 is .020.

Has anyone compared the two Park chain gauges? Which one is more accurate?

Thanks in advance.

Dave

sweeks

There are lots of opinions about the accuracy of various methods of checking chains for wear; I won't go into that.
My only comment is about the Park CC-2. This was the first chain checking tool I got, and I noticed its pins would not go into place on a new chain. I wrote Park, and they replied that the tool is calibrated to be exactly on-target at the "1.0" mark. I've compared its readings to other tools and rulers, and find that it (like most chain check tools that do not account for roller wear) tends to over-estimate chain wear slightly. This suits me, as I can monitor the chain's wear as it approaches 1.0, and then I replace the chain knowing there's a little "safety zone". Yes, the chain is replaced a bit prematurely, but the rest of the drivetrain lasts longer. Chains are relatively cheap, compared to cassettes and chainrings. FWIW.

gkamieneski

I am sure many mechanics here will tell you that the most reliable method is using a 12 inch ruler, but I have had good luck with Park’s latest chain checker, the CC-4. I too had a CC-2 Park Chain Checker and did not consider it reliable.

As for your chain breaking have you considered that you may have gotten stuck with a counterfeit chain? They’re out there. I went through 2 KMC packages until I found the real McCoy. The counterfeits were noticeably poorly manufactured and out of tolerance.

FBinNY 

This reminds me of the old line about the guy with two watches who never knew what time it was.

My first suggestion is to either chuck one checker or buy a third as tie breaker.

Seriously, chain wear is progressive and there's no exact point dividing OK from "replace now".

So first ----- STOP OBSESSING ----- and replace your chains somewhere in the grey zone based on convenience. Or, you might for example, replace sooner with a new cassette, and later when the cassette is already showing wear.

Or, you might consider one checker showing wear as "get ready" and pull the plug when the second confirms.

Either way, chill out and enjoy riding.

BTW - chain stretch is rarely implicated when chains break. Breakage usually relates to a poor closure, or a plate coming off the end of a pin, or occasionally to a plate stress cracking. A good close up photo of both sides if the break might lead to a decent explanation.

Andrew R Stewart 

My first thought was about what caused the broken chain, not any wear measurements. Andy

pdlamb

I've only seen one chain break -- on my wife's bike. It wasn't significantly worn, but the dirty oil on the chain (oops!) highlighted cracks in many of the side plates. So treat the "how worn is the chain" separately from the "why did the chain break" question.

Andrew R Stewart 

The vast majority of broken chains I see are not actual cracked, fractured or have other metal failure causes but are from the side plate coming off of the pin's end. When chain manufactures talk about "strength" they usually are referencing the resistance of this plate coming off of the pin, not how much tensile strength the side plates have or shear strength the pin has.

And the number one reason for the side plate to come off the pin's end is bad shifting. As the chain is being forced (by the der and due to the rider's moving the shift lever) to engage two cogs/rings at the same time it sees pretty high twisting/prying stresses. When the first side plate grabs an adjacent cog/ring it is trying to pull the other side plate along but pedaling pressures are trying to keep that chain as straight as possible. Most all modern chains have the pin ends peened over a bit, like a rivet. It is this "mushroomed" end of the pin that keeps the side plate from working completely off in normal conditions (as when the rider has shifted with good "no pedal pressure" technique).

So when I see "broken" chains I also usually talk to the customer about how to avoid this in the future and learn to shift in a way that is less abusive to the chain.

There have been some broken chains that are because of cracking/fracturing side plates. I've only seen this at the side plate pin holes and only a few times (of the likely hundreds of chain repairs I have done). Sedis (before they became Sachs then SRAM) had a production run of chains where the side plates were over hardened during manufacturing. One was on our tandem but didn't completely break loose before I caught the problem. Andy

Note- I exclude the chain failures due to improper assembly. But these failures are almost always from the pin not being properly or completely pushed into the chain.

drlogik 

I don't measure my chains. I've been riding since 1974 and have never broken a chain. Chains are cheap in the scheme of things. I probably change my chain out too soon but I figure it's one of those consumables that is a real pain to deal with if it does happen, hence I change it out usually once every two years or so.

mpetry912 

really ? Four park chain guages ?

for the price of those you could buy the Rohloff tool and get the answer "time to replace" in this case

the park chain guages make no sense to me.

but what do I know

/markp

jays35

Thanks for all the comments!

L134 

I am not seeing a material difference? Mostly just having fun, though.