I'm a ruler guy myself. 15" metal rule with 1/64" gradations is nice. I also use my Park spoke ruler a lot, as it has a 12 and a 1/4" ruler on one edge.
Chain checkers measure roller wear + pin/plate wear.
I don't care much about roller wear, just the pin/plate wear.
1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1999 Diamondback Interval * Olde Western Auto Cruiser.
Could you please tell us which chain manufacturers feel it is in their best interest to have their customers changing chains prematurely? I ask because everyone seems to have an opinion about which company makes the best, long lasting chain. I don't think any of the main chain manufacturers are interested in making their profit by having chain life wasted. Al
It's for the reason listed in these last few posts that I stay away from the chain checkers. I've heard on many occasions that the chain checker tools (especially the smaller park one) show brand new chains to be 25-75% worn out immediately.
Using roller to roller distance to judge chain wear certainly is the easiest approach, but it's a very poor choice. Wear inside chains first occurs between the pins and rollers. This wear will be indicated to some degree by these 'chain checker' tools. But in my understanding, 'worn chains' don't start actually damaging or causing wear to your cassettes and chainrings, or even slowing shifts) until the actual distance between pins is increased... i.e.chain stretch. Chain stretch can ONLY be measured by accurately measuring pin to pin distances on the outside of the chain, not roller to roller measured on the inside of the chain. The easiest way of doing this is to hold an accurate 12 in. ruler up to the chain and see.
The loud argument that you're hearing here is more than just "use a ruler because it's a cheaper tool for the job," but rather "Use a ruler because it's a more accurate and appropriate tool for the job."
A precison 12" machinist's rule will accurately measure the change in the chain's pitch, but not all chains wear out with increasing pitch as the worst type of wear. It's common for a Campy chain to show only a small increase in pitch, even after 5-6,000 miles of use. At the point, the chain will have severe wear on the rollers and the side clearance may be twice that of a new chain. The chain is shot, but the ruler will say it's OK.
I never use a chain checking tool. I use the internal tips of my dial calipers to measure the increase in roller spacing, in addition to the 12" rule. Campy chains will measure .200-.205 inch when new and most other brands will measure .210-.215. I use chains in groups of three and alternate to a new one when the roller spacing increases by about .015-.020 inch. When all three chains have seen some use, I start the rotation again. This method insures that none of the chains will ever skip on the cassette that they are beinf used with. I consider the chains to be completely worn out when the roller spacing increases by .030-.035.
With chains that suffer more wear at the pins (increasing pitch), the chain doesn't need to be tossed when the elongation reaches .5%, if you're using a group of three chains, since you're not trying to avoid new-chain skip. Just change to another chain in the group before reaching .5% elongation.
Last edited by DaveSSS; 08-11-12 at 08:14 AM.
"We're not living in the day of the long life 5 speed chain"
I haven't noticed any drop-off in chain wear rates over the many years that I have been riding.
I have noticed that certain brands and models of chains wear quickly.
I know that in the old days it was more common for riders to keep riding with perhaps 2% or more chain stretch, while with today's sprockets the shorter teeth might hasten the point at which a chain starts actually skipping.
I get around 4-5k miles before a road chain shows .5% wear, even with 9-speed chains. I don't have a lot of miles riding on 10sp chains, but I do work on many rider's bikes who have 10 and 11-speed chains.
I have had issues with SRAM chains requiring more-frequent lubrication to remain silent.
It is possible to use a normal 6" digital caliper to accurately measure chain wear, but you have to subtract a 1.2XX" measurement from the 5.2XX" measurement. The result (after subtraction) is that 4.00" is new and 4.020" is worn to .5%. There is thus no roller-wear effect on the result.
I developed this method myself and have used this method now for about 15 years.
Shimano's rep gave me one of their go/no-go guages which seems to accurately detect the 0.5% wear level independent of any roller wear.
I see bike shop personnel over-selling chains all the time by using the various "chain-checkers" which add roller wear to the pitch/stretch measurement. That is the real value of such tools, to sell more chains.
Last edited by dddd; 08-11-12 at 05:56 PM.
Regardless of any consideration for the accuracy of a metal ruler vs a chain checker, and in spite of the obvious minute monitoring that some people on this forum give their chains, most of the drive trains that I see come into the shop are either clogged with grease or have seen almost no lubrication. In either case, I can use a Park Tool chain checker ( which fits in a pocket much easier than a 12" ruler) to easily verify that the chain has so badly exceeded the wear limits that the cassette or freewheel also will have to be replaced as well. When at the 100% wear indicator, there is enough horizontal movement to indicate a 110 to 125% wear - arguments about accuracy are incidental - the chain is toast. Difference is also that I can use a chain checker in poor light or with my eyes closed under those circumstances and still confirm that the issue exists. Faster than with a metal ruler.
I do find it curiously interesting though that some of the people that are obsessive about the minor possible accuracy difference between a 6" chain checker and a 12" ruler on an expendable low cost item like a chain, also feel that the use of a torque wrench on major, high cost components - is not required, and that 'personal experience and feel' is the best way to go.
Campy chains can wear the sprockets enough to cause new-chain skip, even when they show less than .2% elongation. I'ved measured .15% elongation after 6,000 miles, but at that point, the roller spacing had increased from .200 inch to .235 inch or more and the side clearance was nearly twice that of a new chain. When a new chain was installed, it skipped on the most-worn cog. Rather than toss that cassette, it could be used with any chain having only a few hundred miles of use (with some other cassette).
What this proves is that both types of wear can be important. Most other brands reach .5% elongation about the same time as the rollers are worn excessively, so the chain gets tossed without considering the roller wear.
Again, if you measure two different lengths with a common, cheap digital caliper, and then subtract one measurement from the other, the difference is as accurate as measuring the chain from the pins or from any two rollers both pushed in the SAME DIRECTION.
I use the 1.2XX" measurement subtracted from the 5.2XX" measurement and the wear limit is 4.020" (0.5% elongation).
The prev posters are correct that the roller wear and tolerances can be a very substantial percentage of "total" wear measured over only a few inches of chain length, giving a 100% pessimistic reading in many cases when compared to an actual "stretch" or "pitch" measurement, which is all that a sprocket's teeth would care about if they could talk.
A chain will continue to mesh well with the sprockets until a very large amount of elongation is reached , like 1.5-2%. As the elongation increases the rollers ride higher up on the teeth and the load becomes concentrated on only the last 1-2 teeth that are engaged with the chain. The chain may actually skip over the top of the teeth, or break off the tip of a tooth, due to the heavy loading.
Chains are changed far ahead of this amount of wear to prevent new-chain skip, not because they are meshing poorly with the sprockets. If a chain is used for too long with a cassette, a new chain will skip on one or two of the most-worn cogs. Some bike mechanics will recommend a new cassette with every chain, but that's not cost effective. As long a new chain doesn't skip with a used cassette, there is nothing to be gained by installing a new cassette. Eventually, there will be enough wear on a cassette that there will be chain skip with a new chain and it must be tossed, or only used with partially worn chains (perhaps on a bad-weather bike).
I take a different approach and use chains in groups of three. I alternate to a new chain a little eariler than normal, to insure that there is no new-chain skip. After all three chains have some use, continue alternating chains a little more frequently than normal and they can all be used well beyond .5% elongation (or up to .240 inch roller spacing with a Campy chain).
I prefer to lay a 12" precsion machinists rule on the edge of a pin. When new, the pin at the opposite end is covered by the rule. When nearly 1/2 of that pin is exposed, then you've reached .5% elongation.
When I've done chain wear testing, I made my own full-length measuring device with a tight fitting pin at one end and a precision machinist rule mounted precisely 53 inches from the center of the pin. Slip one end of the chain over the pin, then read the total elongation at the other end.
Last edited by DaveSSS; 08-12-12 at 11:24 AM.
Interesting notes on Campy chains, will have to keep them in mind. Back when I had a Campy cogset I was running Sedis chains on them.
1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1999 Diamondback Interval * Olde Western Auto Cruiser.
With all due respect, this is where the math kinda escapes me. The inner bushing thickness of bushingless bicycle chains is typically only 0.65mm. The roller thickness is only 1.2mm. They are both the same hardness and material, and there physically isn't enough material thickness in a roller to let it support 10 times the wear as the inner bushing will. What am I missing?Roller wear is as much as 10 times greater than pin/bushing wear, so the wear on a pair of rollers can be as great as the elongation, measured over a short length of 5-6 inches.
The implication is that a tool machined to measure two very specific lengths over a 10 pin length (255 and 257mm) can have an inaccuracy of up to 2mm, but a printed, stamped or engraved reference on the same material won't.I've heard on many occasions that the chain checker tools (especially the smaller park one) show brand new chains to be 25-75% worn out immediately.
The claim is that including two rollers in that measurement will somehow have that effect. I find that really hard to swallow since the inner bushing thickness of bushingless bicycle chains is typically only 0.65mm. There isn't enough metal involved dimensionally to support a 2mm error. Personally I might find user inexperience or a damaged tool easier to believe.
Last edited by Burton; 08-12-12 at 01:33 PM.
If you take some careful measurements on a worn roller, you might find the OD to be .005 inch smaller and the ID .010 inch larger, which leaves the remaining wear for the bushing formed into the inner side plates.
The bottom line is that roller wear is much much greater than pin/bushing wear. If a chain checker only mesure over 10 links, then they're measuring only .025 inch of elongation and every bit as much or more roller wear, just by measuring the rollers at each end of the tool. If might be hard to believe, but it's easily proven with a pair of calipers.
The only way that a chain checking tool can be made more accurate is for it to be shaped such that it's not reporting the true increase in distance between the rollers at each end. It wouldn't be difficult to put in a fudge factor that assumes the roller wear might equal the elongation at .5%, so the tool would actually report a reasonably accurate figure. You do that by having the tool measure .050 inch of additional length over 10 links and put on a label that says .5% at that point (only .025 inch).
The chain rollers get worn both from the inside and from the outside. From the outside from contact with the gear cogs and from the inside from contact with the bushing surface of the inner plates. None of that can be measured using a ruler and pin to pin measurements.
The bushings themselves also wear in two directions. The inside from contact with the chain pins and from the outside from contact with the rollers. The only wear thats referenced by center to center measurement is an indirect approximation of the inner bushing wear. Indirect approximation because the dimensional elongation is a combination of both the channels being cut in the chain pins by the bushings, and the simultaneous resulting thinning of the bushings themselves from that contact with the chain pins.
Chain elongation measurement by pin center to center references doesn't reference inner roller wear or the resulting thinning of bushings from the outside in, but both of those affect pitch diameter.
Theory is nice - I also like to take things apart to have a good idea of whats going on. I think part of what you included as roller wear was actually bushing wear - from the opposite direction. Its actually possible for the rollers themselves to completely wear through those really thin bushings.
So although I share your strategy of rotating chains, I have mo issues chucking a chain when a chain checker says its toast. The numbers you posted, as I stated, are open to interpretation an the math still doesn't work for me. There isn't as I stated, enough material involved for there to be a 2 mm inaccuracy.
Last edited by Burton; 08-12-12 at 05:05 PM.
I'm sorry that you can't believe that Campy chains are that much different, but they are. You may also find that Wipperman chains are very similar. The difference in the space between the rollers is just a combination of small differences in the roller OD, ID and bushing OD, that all add up to be .010-.015 inch.
I don't understand the 2mm or .08 inch inaccuracy that you're talking about. Most chain checkers add the wear on one pair of rollers to their length measurement. That's the same wear that I'm measuring with caliper tips between the rollers. That could be as large as 1mm or .040 inch of additional length that's not elongation. If the tool measures over a length of only 5 inches, that's .8% of false wear. As I mentioned, it is entirely possible for a chain checking tool to have a fudge factor built in so it reports a different length than calipers would.
FWIW, Campy recommends using calipers and tossing a chain when the length measurement between rollers increases from 5.200 inch to 5.220 inch, which is only .4%. At that point, you could scarcely detect any increase in the chain's pitch, even using a 12" precision machinist's rule. That's why I built a full length measuring device to more than quadruple the change in length that I was measuring and improve accuracy. Campy's recommendation is extremely conservative and what I consider to be a half worn chain. When I use chains in groups of three, that's when I exchange the chain for the next new one, but I certainly don't toss a chain with that little wear.
That is surprising that Campy suggested measuring with the caliper that way. So I guess they are saying that something like .2% might be the limit?
I could see .4% being a good number for a corrected stretch/pitch measurement though, since the Record cassettes sell north of $200 and get scarce over time.
It would be more than a hassle rotating chains with those special press-fit links though.
I used to use Campag's method of direct measurement 20 years ago with a 6" dial caliper, which I modified to read out to 6.2XX" and usually used 6.230 as the limit iir. I was wasting chains!
I remember one new DID Lanner chain registering as being over 6.230" after only 550 miles, which was obviously not indicative of much actual stretch.
I always use Shimano chains as replacements on Campag drivetrains, since they cost so much less, require no special tools to install and last at least as long while seeming to require less copious lubrication to remain silent.
In most cases, the Shimano chain is a touch narrower, which always seems to improve shifting. Campag even recommended use of their narrower C9 chain on their own 8s drivetrains at one point.
I advise and practice never to remove or clean a bike's chain during the service interval. I apply a continuous fine stream of diluted lubricant to the point of semi-saturation onto the moving chain, followed by a wipe-down with a terry shop towel.
The sprockets (and pulleys) get cleaned while rotating using a machinist's rule (and screwdriver tip), respectively.
From there, a rag pulled thru the cassette's gaps can pretty things up as needed.
Last edited by dddd; 08-13-12 at 01:55 PM.
I use Campy's pin for the first installation, but use a master link after removing a chain for cleaning. I use the same technique of applying a heavily diluted homebrew chain lube to help flush out dirt, but after enough weeks, the road grit here in Colorado gets to be too much, so I take the chain off for cleaning.
One of the silliest myths about chain cleaning is that is harms the chain by removing "valuable" lube. Sure it remove the lube and dirt, but removing wear casuing grit is the idea. A thin lube penetrates the pins, rollers and bushings in a matter of seconds.
A Wipperman connex link is my favorite design, but it's a little bit of a sloppy fit on a Campy 10 chain and there is no 11 speed link. IRD makes one that looks decent and of course, KMC chains come with master links.
Here's another little known fact. Even though all brands of 10 speed chains now have the same 5.9mm width, the width across the inner plates is not the same. Campy and SRAM were both about .1mm narrower, the last time I checked. That's what makes both Wipperman and KMC links a sloppy fit on a Campy or SRAM chain. KMC chains tend to have more side clearance, when new, than the other brands and their master links have an even looser fit. Typical side clearance for a new chain is in the .004-.008 inch range.