Or get a "11" rule" .. Its really silly estimating outside the scale when can just use 11" or 11.5" as the reference length. (pin to pin distance in any bike chain is 0.5").

That has nothing to do with the post you quoted.

Sure. Its all over the place and opaque what the percentages is in reference to. Some toole even uses mm rather than %. Thus I made up my own campy like system, but with significant more allowance for wear, as mentioned in an earlier post. Ive been meaning to get a shimano chain checker to see what they consider "worn out" but so far I haven't. If anyone has one (or any other brand) and a digital calliper id be interested in the go/no go dimensions of such tools. I'm betting they too are all over the place.

If a chain checker's instructions say that the chain should be replaced at .5%, that doesn't mean the chain should be replaced when a ruler shows .5% elongation. They measure different things.

Sure. Please do that :thumb:


I have measured new Shimano, KMC and a YBN 10s chains. They were all close to 132.25 mm when measured as suggested by campy.


Taken at face value and assuming 132.6 mm is representing 0.5% wear. A new chain should measure ~131.94 mm. However they dont. I suspect the engineer calculating the numbers forgot to account for slop in the rollers that adds at least a few tenth of a mm. That, or a campy chain has bigger rollers than shimano and the rest of them. I dunno?


No matter, I have found the campy method doesnt work well with shimano or other generic chains. A lot more wear is tolerable than tossing the chain at 132.6 mm.

Is it? Im not convinced.

Shimano, SRAM, Park and others all have chain gauges that are designed to exclude roller wear. Seem to indicate roller wear is not significant and including it may in fact hinder measuring the the relevant wear component.

I'm not gonna let you off that easy; you made an absolute statement and I'm telling you to prove it. Post a pic of the tool you say is far more accurate and tell me why it is. You were pretty confident, so it shouldn't be too much trouble.

Like this?
https://cimg4.ibsrv.net/gimg/bikefor...e564b25e16.jpg
Or this?
https://cimg5.ibsrv.net/gimg/bikefor...16d5e22ea5.png
How do these checkers, which engage only the rollers, fail to measure the roller wear along with pin wear?

Yes, like that.

They measure elongation with the rollers pushed in the same direction, where older model gauges pushed rollers in opposite directions, thus adding roller wear to the measurement. Im not aware if this was attempted taken into account or not.

Funny how the SRAM gauge allows for up to 0.8% true elongation, 60% more wear than the oft cited 0.5%.

Manufacturers recommendations and Park's recommendations may have always been different. Car manuals have never actually recommended 3000 mile oil changes, either.

You are right that the pins get pushed the same way, subtracting the roller wear. I wonder if they consider that more accurate, or if they are bowing to public opinion that rollers shouldn't be checked after decades of doing exactly that.

A 5mm hex key used as a go/no go gauge. Hang a new chain against your used chain. More than 4mm and I bin the chain.

The reason is better resolution. By far.

No doubt about it, there are a few ways to get the job done. He made a statement of fact (according to him) and I want him to explain it.

Say wut? I've driven cars whose manuals recommended changing the oil at 3000 miles (blanket recommendation) and later cars that recommended a 3000 mile interval for cars driven in stop and go traffic.

Somebody help me with the math here. The way I see it, you compress two links' rollers, and subtract that from four links' rollers, and the net roller wear is zero? I'd have expected you're only getting two links' roller wear instead of six.

He can copy my answer. LOL. A 5mm hex key is a tool. (my limit of 0.4% is conservative but that is for a reason)

Hare is a pic of the Pedro's version. Park makes one like it. One more time, it eliminates the roller from the measurement.
Pedro's Chain Checker Plus II | Jenson USA

I do agree with you but have to ask why are you making such a big deal about roller wear? Measuring with a rule or measuring with a chain checking tool gives the same result so the measurement is equivalent and we don’t need to know anything about roller wear. There’s no need to even be concerned about it…if it even happens. It. Will. Make. No. Difference.

The looseness of the rollers will cause wear on the cogs but that looseness is related to the pin wear so if we measure pin wear, we end up in the same place with regards to the need to replace the chain. Again, there is no reason to be concerned about the what little (if any) roller wear occurs. It’s a nonissue.

The recommendations are all over the place because wear is a range rather than a hard value. It’s not like you are supposed to change your chain at 3247.3 miles, no more, no less. The whole “rule method is more accurate” argument is kind of silly since there isn’t a given value for chain wear. We replace chains when we get to about 0.75% (0.094” elongation over 12” or 3/32”) to prevent wear of the cassette and, to a lesser degree, the chainwheels. And that’s only for derailer bikes. Single speed or IGH chains can go for many more miles because they aren’t being shoved from side-to-side regularly.

The rule method folks always point out the horror stories of people showing a worn out new chain to hammer home their point that their method is “better”. I would hazard that the vast majority of those kinds of measurements are user error.

The standard chain check tools like the CC 3.2 take the pin wear and add the wear of the the two rollers. That will give a different distance than measuring the pins alone if the rollers have wear.

If the rollers have wear, that wear directly impacts chain pitch when wrapped around a sprocket.

Elongated chain pitch is what wears out sprockets prematurely.

If you want to know what the chain has for actual on-sprocket chain pitch, you can't ignore the other source of elongation: The rollers.

You can't measure roller wear by measuring the pins alone.



That is the last time I'm going to explain that to you. The fact that seemingly flip flop between understanding and not understanding what a ruler measures makes communicating with you too frustrating.

No wonder you were banned from the General subforum.

Yeah, why can't I be polite and friendly like you?

I participate in all sorts of forums about all sorts of topics. This particular one is full of interesting problems that I love; but also aggressive, dismissive, passive aggressive and insulting people who seem to hate nothing more than someone who actually knows what they are talking about. It is mind numbing how hard it is to have to explain, explain and re-explain even the most basic geometrical concepts to other adults who think I'm being ridiculous for suggesting that bikes work the way they actually do.

Instead, I should be like the typical person I end up dealing with post after post - someone who doesn't seem to ever suggest an actual solution to anything, doubts and dismisses everything and takes personal swipes at anyone actually useful to make themselves feel better for being little more than an aggressive doofus. I don't know why that's the way it rolls here and other bike forums, but maybe you just don't have to be very smart to pedal a bike or type on a keyboard.


I love my writing forum. Everyone is smart and the doofuses get banned sooner rather than later. People actually like it when someone has knowledge or ideas.

I'd think you were being ironic if I didn't know better.

The problem with you is that you never stop to consider that you might in fact be wrong. In pretty much every topic you have a rigid (and often quite simplified) opinion of how this or that particular thing works and that opinion is then dogma, the pinnacle of science (even with no evidence) and the ultimate truth. All other possibilities are simply false and not worth even considering.

I see that a lot in my profession. The strange thing is that people don't learn even when they are shown to be wrong in the most definite possible terms.

Actually, I don't have any rigid beliefs. What I have is a consistent attempt to explain my POV to people that seem to refuse to even understand what I'm talking about to disagree or not.

We can have a debate about whether roller wear is a factor in cog wear, and I am entirely open to being shown to be wrong. Just as I admitted a few posts ago that the new Park tool removes the rollers from the measure. But we can't have a conversation about the topic of roller wear if people don't understand where the parts of the chain are. And that stuff ends up being half the posts.

It is tough having an engineering conversation mixed with remedial topology. Especially when the people that really don't get it are insulting.

I spent my whole career measuring stuff

Go/No Go gauges were put in place for monkeys.

0.75% is way too much to prevent chainring or cassette wear. Secondly, once wear starts on a chain, it is not linear. So, 0.4% is when my chains get tossed. It can be as little as 4,000 miles or as much as 10,000 miles.

I'll let the rest of you argue about rollers.

It might save you some aggravation if you share your engineering credentials in a signature. In my experience, folks here are respectful of actual expertise. :thumb:

I don't know. Only you or maybe a therapist can answer that.

Lots of anger and rage in this post. Don't let your rage consume you. It's not healthy.

Pins, rollers, who cares? All I know is that the humble ruler lets me know when to replace my chain. And I also know that chain checkers can read worn before the chain really needs to be replaced. And I have never trashed a cassette by leaving my chain in service too long. And you know what? I get about 8K miles out of my chains.

I remember a good quote from a good wheel builder on RBR that is appropriate here. "With bicycles in particular, you need to separate between what's merely true and what's important".