Chain checker accuracy

[LegendRider]

Which Park Tool is more accurate? I have both and get radically different readings. The one-piece (CC3) unit says my chain wear is less than .75% and the other gauge (CC2) says > 1%.

[skijoring]

I would use a ruler, gives a better measurement. There is lots on the Great Google about this. Bikeforums mecanico section - among lots of others.

[Dave]

Neither one is accurate since they both add the wear of a roller at the end of a very short measurement. The roller wear can be as great as all of the pin/bushings that create elongation, resulting in a report of up to twice the actual elongation. That's at the very best, if you discounted whatever "wear" the tool shows on a new chain. A Shimano chain will often show .25% wear when new, but that is not wear, it is the smaller roller and greater clearance between roller and bushing that the tool is measuring.

Use a prescision 12" scale to measure elongation. Place one end of the scale on the edge of a pin. The pin at the opposite end of the scale will be covered by the scale when the chain is new. When .5% elongation has been reached, almost half of the covered pin will be exposed.

If the chain is from Campy, other parts of the chain may wear out long before .5% elongation is reached. I use calipers to monitor roller wear and feeler gages to measure side clearance.

[LegendRider]

Place oned end of the scale on the edge of a pin. The pin at the opposite end of the scale will be covered by the scale when the chain is new. When .5% elongation has been reached, almost half of the covered pin will be exposed.

So, if I use a steel ruler, I should place it at the edge - as opposed to center - of the first pin?

[chuckred]

Neither one is accurate since they both add the wear of a roller at the end of a very short measurement.

Hard to believe that they weren't smart enough to build that into their design of the tool. I'll have to go measure now!

[thwart]

A Shimano chain will often show .25% wear when new, but that is not wear, it is the smaller roller and greater clearance between roller and bushing that the tool is measuring. As long as we have your attention, Dave---is this one of the reasons why some folks I ride with (who ride Shimano) can razz me about having a drivetrain that makes a bit more noise than theirs? Shimano chains are designed to be a little looser, so to speak?

[Dave]

Measuring inside edge to outside edge is the same as center to center - an old carpenter's trick. They always measure that way to get studs or joists 16" c-c.

Yes, it's hard to believe that those chain checker tools have such a flaw. Shimano actually makes one that eliminates that error. I don't see the point when a 12" machinists scale works well and is easy to use. As an example, when the chain reaches .5% elongation, the wear on 12 pin/bushings is .030 inch. The roller spacing is quite likely to have increased by about that same amount - thus the report of double elongation. I trash a Campy chain when the roller spacing increases by about .040 inch. The only way that one of those tools could measure more accurately is to make it so the reading assumed some amount of roller wear. If that was done, then the tool could be made more accurate. In other words, the tool could measure .060 inch of combined elongation and roller wear and report it as .5% "elongation".

The .5% number is totally arbitrary. Using Campy chains, it's meaningless. I get far more chain and cassette life by alternating the use of 3 chains with one cassette, rather than tossing half worn chains and perhaps using 6 to get the same mileage. Eventually, a new chain will still skip when installed on worn cogs and those 3 additional chains were wasted just trying to avoid chain skip.

The fact that shimano rollers are a little smaller and/or have a little more clearance with the bushing should not make the chain any noisier. I've used both Shimano DA chians and KMC chains on my Campy 10 bikes and never thought that either was noisier. Using a dry or very thin lube is a common source of noise. I conducted a wear test with WD-40 as chain lube and noticed a noiser chain. From that test I can advise not to use WD-40 as a regular chain lube - it produce far more elongation than my regular homebrew.

http://www.generaltools.com/Products/Precision-Industrial-Stainless-Steel-Rulers__Industrial_Rulers.aspx


http://www.generaltools.com/images/ruler_blowouts/1216.jpg

[oldpotatoe]

Which Park Tool is more accurate? I have both and get radically different readings. The one-piece (CC3) unit says my chain wear is less than .75% and the other gauge (CC2) says > 1%.

To answer your question, the CC3 is more accurate than the CC2. The Prolink or Rohloff ones are more accurate than the CC3. A ruler is the best, as has been mentioned. But use the least expensive compatible chain and change fairly often. Same for cogset, use the least expensive compatible one. They are consumables, afterall. No performance gains with a more expensive and slightly lighter, cogset or chain.

[Mikej]

there would actually be 4 measurements, so none of the chain checkers on the market are valid. One would have to measure with a vernier caliper the 1. new roller size, and then 2. measure roller to roller (again - new) and then 3. pin to pin (side plate stretch). Remember, the worst damage happens INSIDE of the roller against the 4. (unmeasurable) pin underneath where all of the gunk resides.
Ijust get a new chain every 1k miles - love that new chain feeling, best 40$.

[khjr]

I trash a Campy chain when the roller spacing increases by about .040 inch. [....] The .5% number is totally arbitrary. Using Campy chains, it's meaningless. I get far more chain and cassette life by alternating the use of 3 chains with one cassette, rather than tossing half worn chains and perhaps using 6 to get the same mileage.

Good post.

What's the basis for discarding the chain when the roller spacing increases to 0.040", and how are you measuring it? (calipers between the rollers?), and why do you say that pitch is meaningless for Campy chains?

I also rotate 3 Campagnolo 8 speed chains (typically the Sachs PC68/890 style) on a common cassette and have two sets of chains/cassettes with different gearing for Connecticut vs. Vermont/Europe.

I understand that roller spacing is what's critical, as that's the surface presented to the cog teeth and the measurement combines the pin, bushing, and roller ID/OD wear that change pitch. However, using the aforementioned strategy (sets of chains on a common cassette), it doesn't seem that it would matter whether the bushing to bushing distance had elongated or not. What am I missing?

Also, in an earlier post you mentioned using a feeler gage to measure wear. Can you share your thoughts on that?

[Dave]

Mikej....

All those measurements are NOT needed. Elongation is simply measured with a scale.

If you want to keep track of roller wear, you can measure the space between the rollers at several locations on a new chain, then compare it to a used chain. Chains within a single brand shouldn't differ much.

Campy chains measure the smallest, at very close to .200 inch when new. Most of the others measure in the .210-.215 inch range, which is why the tools show .25% elongation on those chains when new.

You are correct that the greatest wear occurs inside the roller and around the bushing formed into the inner side plate. After lots of use, the OD of the roller may be .005 inch smaller, but the ID is likely to increase by twice that amount. When you place internal caliper tips between the rollers, you get a mix of the wear at 3 places (OD, ID and bushing OD) times two.

The .240 inch value I've set as my limit for a Campy chain is entirely arbitrary, when the chains are used in groups of three on a cassette. After that much use, the cassette won't mate with a new chain, so you can't hurt it any more. The only thing to worry about then is the effect of the worn chain on the chainrings and the sloppy shifting that you may get as the side clearance approaches twice the original amount.

I once used a Campy 10 chain for 6,000 miles on one cassette and got chain skip on the 19T cog when a second new chain was installed. That chain only had about .2% elongation, but the space between the rollers was about .240. That taught me that the experts who claim that only elongation is important were wrong. I did even worse damage to the 19 and 21T cogs on a Ti cassette in only 4,000 miles with one chain, that had even less elongation. No more Ti cogs after that.

[Dave]

khjr...

A well maintained Campy chain will not usually reach .5% elongation or anything close to it before the rest of the chain is shot. If it does, that says that you have a problem with your lube, lube frequency or cleaning technique. It means the pins and their bushing either don't have adequate lube or there is grit in there, wearing out the chain. All other brands I've tested show far greater elongation.

I've measured side clearance of around .013 inch on a well used Campy chain, whihc is about twice the amount when new. I didn't notice shifting deterioration at that point, but some people claim that's why they change a chain, to improve shifting.

[thwart]

The fact that shimano rollers are a little smaller and/or have a little more clearance with the bushing should not make the chain any noisier. I've used both Shimano DA chians and KMC chains on my Campy 10 bikes and never thought that either was noisier. Using a dry or very thin lube is a common source of noise. Thanks.

I do use a wax based dry lube on a couple of my bikes that never see any water; I suppose that's likely the answer. Nice to have a really clean drivetrain.

I conducted a wear test with WD-40 as chain lube and noticed a noiser chain. From that test I can advise not to use WD-40 as a regular chain lube - it produce far more elongation than my regular homebrew.
Could I talk you into doing a long-term test on the product I use... ? ;) :D

[Dave]

Could I talk you into doing a long-term test on the product I use... ? ;) :D


I think my chain wear testing days are over. This coming year, I may do less cycling since I'm putting my house up for sale and move to a different home, north of downtown Denver. We plan to rent for up to two years, until I find some rural land around Loveland and build my final retiremement home. If that goes as planned, I may not cycle at all for nearly two years, while I'm acting as general contractor and doing some of the work. Right now, I'm designing a large ranch style home with at least 1500 sq. ft. of separate shop space for building hot rods.

[excel1959]

Forget measuring. Use KMC chains and replace every thousand miles. Simple and works like a charm. My cassettes on multiple wheels work forever.

[Dave]

KMC chains are not all that cheap. You can spend far more money tossing perfectly good chains instead of a few minutes measuring.

Tossing barely worn chains does NOT prevent cog wear. Eventually a new chain WILL skip when installed on a used cassette. It might take 15 chains but it will happen.

In that same 15,000 miles, I'd use three chains on one cassette. What's an extra 12 chains cost?

If you want a cheap and brainless method, buy 3-4 chains and change to a different one every 1,000 miles. After all the new chains are used, start over. You don't have to measure anything, unless you can't keep track of which chain has been used 2-3 times, then get a out a ruler. Toss the whole mess after 15,000.