Edit: I can't change the title but I meant to write less than 0.75. The chain definitely passes through the 0.5 mark on the tool.
I bought a trek verve 2. After 3 months / 300 miles I stopped by for something else and they did a quick chain check and told me the chain was already at 0.6 and that I should degrease and lube better which I started to do monthly after 100 miles.
Now after 1000 miles I brought it in for a complementary level 1 tune up and they told me the chain is beyond 1.0 and needs to be replaced and the cassette is therefore shot too and also needs to be replaced.
To me the chain looked good, perfect shifting, no noise, no grit, so before agreeing to that work I bought a pedro chain checker and though it's the first time I'm using I cannot even get past the 0.75 mark. I tried it 4 times in different locations and I did pinch the chain to the tool between the two hooks.
Is it really possible that the professionals at the trek store are measuring this wrong? See attached the tool they are using, could it be that this tool is less accurate and the roller wear makes the difference? (I read about that before buying the Pedro)
Since I am probably just shy of the 0.75 mark I will put on a new kmc x8 anyway but I assume no need to change the cassette?
I'm new to bike ownership and maintenance so I'm doubting myself compared to the service manager at a corporate trek store.
by RHOUTX
13 Comments
Some chain checkers don’t work on all chains. If the roller is a different size it will throw it off.Â
If you need a tie breaker, measure pin to pin with a ruler. 1/8 Inch over 12 inches is about 1%.
UPDATE: I found a good description of how roller thickness throws off chain checkers in the first section at https://www.stirlingcyclingchronicles.com/post/the-best-chain-checker-tools-of-2024
It’s a bit premature to replace the whole drivetrain (but that’s what shops are for so they’ll do it) and we don’t even know what gauge exactly the shop used, it could be an inaccurate style.. personally I never replace sprockets until they’re skipping with a new chain. I don’t know about this Pedro’s style but I’d suggest getting a park tool cc4 which is way more accurate and appropriate for 11-12s
Replace the chain and then replace the cassette if the new chain skips.
That tool in the photo is basically garbage much like the Park Tool version. It’s so easy to push too hard and read more wear than it actually has.
*Every single 2-point chain checker is inaccurate*. 2-point chain checkers do not isolate pin wear from roller wear, which means they read higher than reality if the rollers are worn. Some try to compensate for this by accounting for some set amount of roller wear in the reading, which makes them read lower than reality if the rollers are *not* worn.
This fact is surprisingly either not known or intentionally ignored by some shops. I’ve encountered a shop who told me my hot waxed Dura-Ace chain with 300 miles on it (quite literally 0 measurable wear) has worn to 0.5% and needs to be replaced because of their 2-point chain checker. I told them to go check one of their brand new chains out of the box – lo and behold, their brand new chain also measured 0.5%.
If the shop is using a 2-point chain checker, and if you are using the Pedro’s 3-point chain checker, then you should trust your reading over the shop’s.
That said, however, yes – I’d suggest replacing the chain now. If the Pedro’s chain checker has a weakness, it’s that it does not read beyond 0.75%, so once the chain drops into the 0.75% mark you have no way of knowing how much it’s worn past it. Replacing it now is the best way to ensure it hasn’t worn too far beyond 0.75%.
No need to change the cassette.
1000 miles seems premature unless you were riding in adverse conditions. And replacing the cassette too? With no shifting issues or skipping under heavy load.? I’d probably keep riding it as is, at least until your own chain checker says it’s worn out.
If you get a new chain use your chain checker to measure it in the brand new condition. That will give you some sense of the zero error. So if it reads 0.1 percent stretch on a brand new chain then at least you know you can subtract that from future measurements.
I usually get at least 3000km from a chain.
If you have a set of measuring calipers:
1. set the caliper to 5.6 in.
2. insert the caliper jaws between rollers
3. extend the jaws to tension the chain
——
new chain = 5.715 in.
1/2% stretch = 5.745 in. (~ 1/16 in. over 12 in.)
3/4% stretch = 5.760 in. (~ 3/32 in. over 12 in.)
1% stretch = 5.775 in. (~ 1/8 in. over 12 in.)
I’d just be honest with the bike shop, break down a little of the wall there.
If you haven’t tried em, get a SRAM chain and worry less about chain fragility.
A new cassette can be fun btw, it’s nice learning and experiencing different gears, not saying you need it though.
Just positive thoughts!
A bike shop told me my chain was worn. They used a Perk tool and I believed them due to Parks reputation. Bought a new chain to fit myself from the. Got home and there was very little wear, comparing old with new. The bike was only 6 months old with dry use mostly. That’s why I do my own maintenance and have a distrust of Park tools.
I just use the simple plate style with a curved end. Mark it where a new chain sits and it’s almost impossible to damage one.
Something we have to be aware of are you shop, especially the Park Tool chain checkers is if the tip of the tool bends even slightly, it will make the test invalid. We have to replace the tools somewhat frequently or we have to baby them around. Potentially the cause
Generally you replace the cassette when a new chain doesn’t shift well. If they say replace the cassette and the drivetrain is shifting well, I’d say the recommendation is a bit much. you replace the chain so the cassette and chainring last a long time. When a new chain skips because the cassette is worn, you replace the cassette. Cassette usually lasts 5000-10000 miles for road riding. Chains last 2000-3000 miles.
Good rule of thumb is to, when you get a new chain, check where it lands as a new chain on your checker and then you will have a point of reference as your chain wears. Because not all chain checker brands measure the same.