I've got one of those Park-tool like easy chain checkers that tells you if your chain is stretched 0.75% or 1% by seeing if it fits into the chain.

It easily fits into my chain on the 0.75% side, which indicates this degree of wear, but doesn't fit at all on the 1% side, which indicates it's not this worn.

Instructions say "consider replacing your chain" at 0.75% and "definitely replace at 1%."

Was wondering what you experienced folks do in this sort of situation. I could obviously change the chain right here and now, but I'd rather not if it's unnecessary. Basically, I don't know whether approaching 1% wear is really worn for a chain, or eminently rideable without damaging your cassette. Experienced folks speak up!

I have that tool as well and I always double check the old-school way with a ruler :

https://www.bikeforums.net/showthread...-chain-stretch

A worn chain wears your cassette out faster, but a new chain costs money. It's an age-old dilemma, when to get a new chain. Fortunately, if you are allowed to post in the #41, you've got plenty of money. I'd go ahead and get a new chain if I were you.

PatentCad will be along to tell you he replaces his chain after every ride.

Yes, I'd change it.

ruler as mentioned above. At 1/16" wear I toss it. Good place for the Park Chain Checker also.

+1. The ruler is a much better indicator than the chain checker, because it measures the true pitch of the pins, and isn't affected by the movement of the rollers in opposite directions. I also change chains at 1/16" lengthening.

My chain checked about the same as yours. I replaced mine. A chain is a lot cheaper than the rest of the drive train stuff.

It is your duty to change the chain.

If it's a 10 speed and you're checking it with a CC-2, keep the chain and toss the CC-2 or stop using it on 10 speed. I have no idea why it doesn't work on 10 speed, but it doesn't. I don't know about the CC-3. The CC-2 works great on 7/8 speed and 9 speed.
BTW, yes I change a chain at .75 using a CC tool.

I replace at .75 wear using the Park Tool CC-3 chain wear indicator. As doctor j said in post #7 above, a chain is a lot cheaper than a cassette.

I change it when I notice a degradation in shift quality. Usually there is one shift, either the 15-16 or 16-17, where it goes first. The CC-2 has it somewhere between .75 and 1.0 at that point. I could perhaps run it longer but the shifting bothers me, so the chain gets replaced.

It is your duty to wring every last friggin possible mile out of the friggin chain.

Hang tough my little Fredling.

I use a CC-3, and my foul weather rain/winter bike (8 speed MTB components) goes through chains the fastest, but cassettes and Chainrings will eventually go too. I commute/errand about 5000 miles a year on that bike and go through about 3 chains in that period, replacing at 0.75 wear. During last Winter I went through a chain particularly fast during the second half of the season going to 1.0+ before I realized it, wearing the cassette and my chain rings were old too. I figured even a new chain (I generally use SRAM PC-890) would wear faster on the worn cassette and chainrings, so I just elected to ride the bejesus out of the whole system and then I changed chain, cassette and chain rings when the Winter was over.

Speaking of chains, I've been practicing a really simple method of lubing my chains, particularly on my better bikes:

1. One drop of Tri-Flow on each link on the lower chain run ("inside" of the chain)
2. After riding a good distance, maybe 30-50 miles, use a rag and some mineral spirits to take the black off the side plates.

It *appears* to me that by lubing the inside of the chain and not doing much else that the Tri-Flow washes out the dirt and deposits it on the side plates which you can easily remove with mineral spirits a few days later. Seems to keep my chains clean and lubed for a good while.

I've found with those chain stretch tools, that you must replace the chain as soon as the .75 thing goes in. If you leave it until the 1 side almost but not quite fits, your new chain will skip on the sprockets, and you'll need to replace them too. So yes, get a new chain now.

This is interesting, so what exactly does the 75% mean. If you're supposed to replace your chain when it has 25% of it's life left to prevent wear on the drivetrain wouldn't that in reality mean that it has used up 100% of its useful life? Therefore we should be replacing them prior to 75% since anything beyond that will start to cause wear. Where does this end? I'm going to go change my chain.

it's .75% (notice the point) and it refers to chain stretch measured over 12 inches.

that means for a 12 inch length of chain it has increased by 12*.0075 which is .09 of an inch. 1/16 is .0635 and 1/8 is .125

I use a dial caliper and change the chain when it reaches 1/16

Here is what I found:
1/16” stretch over 12” (12 links) = 0.52% stretch
Rohloff 0.1mm wear for 1” (1 link) = 0.39% stretch
Rohloff 0.075mm wear for 1” (1 link) = 0.29% stretch

I toss chains when my Rohloff indicator indicates 0.29% stretch, I think the 0.5% stretch (1/16") wears cassettes too fast on 9 speed and higher drivetrains. I know that Im throwing out chains before most, but then again my cassettes are lasting a looooong time. 9 speed mtn bike hasntbeen changed in 18 months and who knows how long my Campy 9 has been in service.... I used to burn shimano cassettes every season.

https://www.rohloff.de/en/products/caliber_2/index.html

I read somewhere that the park tool indicates 0.25% stretch on a brand new chain so you have to subtract that from the readings. So your 0.75% stretch is really 0.5% which is the 1/16" stretch that has been the golden rule for decades...

I just wonder if that golden rule should be revised now that we are on 10 and even 11 speed drivetrains...

See post #28 on https://forums.mtbr.com/showthread.php?t=215824

I change the chain when it starts to skip

As noted, toss the chain gauge and use a ruler instead. I've found the gauge to be a really effective mechanism for Shimano, et. al. to sell you chains you don't need.

I like Grumpy's dial caliper approach. It's a little OCP, but I'm the kind of guy who removes, cleans & lubes my chain after nearly every ride, so maybe it's time for me to upgrade from the ruler.

What size caliper do you use, G? Do you measure the whole 12 inches, or some fraction and extrapolate out?

a buddy of mine made a conscience decision to NEVER change the the chain. Instead, let the whole drivetrain wear as a system. Hes gotten 3 years out of his campy 10 speed. He knows he will replace the whole system, but thinks that its lower out of pocket since he gets 5+ years out of his drivetrain without replacing anything.

tj90.....

Even if you ignore the initial .25% false wear that a Park tool reports with some chain brands (due to differences in roller size and clearances), it still combines the elongation over the measured length with the wear from two rollers. The roller wear can be as large as the elongation, so the toll still exaggerates the wear. A precision 12" scale is a far better way to measure elongation.

Campy chains are a different animal. The pins are harder and wear less than any other brand. I've used a Campy chain for 6,000 miles and accurately measured .2% elongation over the full length. Unfortunately, elongation (chain pitch) is not the only dimension to measure for wear. After 6,000 miles, the rollers had a lot of wear. A caliper's internal measuring tips, placed between the rollers measured .240 inch, compared to .200 inch for a new chain. The side clearance was also about .013 inch or nearly twice that of a new chain.

Despite the small amount of elongation, the chains also wore one cog (the 19T) enough that it skipped with a new chain.

If you really want longer chain and cassette life, try alternating the use of 3 chains, changing each one before it's half worn. If you get the third chain into use without chain skip, you should be able to use all three chains longer than you normally would and never encounter chain skip. I'd expect 5-6,000 miles from each chain and only use one cassette. After each chain's first use, you can alternate frequently, if desired, like every time you take a chain off for cleaning.

To add one more comment, a chain should never just start skipping as an indicator that it is worn and needs changing. If it does, it was used far, far beyond any normal point of chaning it and the cassette is also ruined. It's a new chain that normally skips on worn cogs.

I have a 6" dial caliper that I use in my shop. It measures thousanths of an inch. I extrapolate out.

I found wipperman measure less than 12" for 12 links.

Also its a good idea to measure the chain when new. A lot of those checkers read the chain is worn when the chain is brand new (on 10speed)

DaveS: Makes sense what you are saying, use 3 chains when they are half worn then let all 3 wear down gradually and "together". Currently I have 3 cassettes - 1 for mountains, 1 for normal hilly terrain and finally 1 for flats. I paired a chain with each cassette. When I switch cassettes, I switch chains so that they are always paired. I could start using 3 chains on the common cassette so that I virtually have triple the chain length to wear out! The only downside is managing all the used chains in the garage!

Your comment on roller wear as important as elongation is important. Its counter to the mtbr thread I reference, but I think its a worthy metric for wear. Basically you are saying that the rohloff and park methods for measuring wear ase valid since they factor in roller wear too. The ruler method does not.

I too have measured with calipers the distance from roller to roller. I have found the following:

dura ace 10sp Caliper roller to roller is 0.216mm
campy 9sp is 0.2mm
sram 1sp 1/8" is 0.210mm

So not all chains have the same 0.2 clearance.