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Technical FAQ: Chains and chain checkers

Dear Lennard,
On January 5, 2016, you replied to a letter on the website about a 10/11 speed compatibility issue, specifically regarding a triple crank.

I can report that I built up a triple-ring bike this past spring using a gemisch of parts from all three major component groups. I have Campy 11s Athena shifters and derailleurs; a Shimano 10s, 105 triple crank (50-39-24), Ultegra hubs; a SRAM 11-28t, 11s cassette; and an 11s chain from KMC. (The 24 replaced the stock 30 on the cranks.) All parts were purchased new from my local bike shop and I built up a new Ritchey Break-Away cyclocross frame. It shifts very well front and back. I occasionally have a problem where the chain will drop off the 50t chainring (to the middle ring) when I’m shifting from about the 22 to 19 cog. I can’t reproduce it in a work stand, so I’m guessing the chain may “hop” a little during the shift and because of the angled chainline, it just pops off the 50. I don’t run the 50 with the 28 (and rarely with the 25) and it doesn’t happen very often. As the chain has worn, it happened less and less; must be time for a new chain.
— Ron

Dear Ron,
Way to make a ShimSRAMagnolo setup work!
― Lennard

Follow-up on chain-measuring tools:

Dear Lennard,
I recently bought a Park Tool Chain Checker (CC-2), and can’t seem to insert the two ends pins between the links of my chain, because the distance between the two pins of the tool is too long. I have an 11-speed Ultegra chain, only done about 1,000km.
 Not sure if it doesn’t fit because:
1. The tool was damaged/faulty — the pin on the black slider isn’t perfectly perpendicular, but at a slight angle. Is that meant to be the case? The packaging looked to be in good condition.
2. My chain is incompatible, but I can’t think of why this would be the case.
3. I’m using the tool incorrectly, but I am setting the adjuster to zero, and it still doesn’t fit.
— Yi

Dear Yi,
I imagine you’re doing this, but you have to set the tool on zero when you drop it into the chain. If it is, and it still won’t fit, then there is something suspicious going on. The chain is obviously running fine, as you’ve ridden quite a bit on it, so there’s no way that the chain is somehow mis-manufactured with shorter links or something, an occurrence which I can’t imagine could happen anyway. The only conclusion would be that either the tool’s pins are bent outward, away from each other, or the tool is faulty due to a manufacturing problem.
― Lennard

Dear Lennard,
Maybe it is not significant enough of a variance to need something more advanced than a tape measure, but it is 2016. We cannot simply and cheaply use either a laser or electricity to measure the length of a metal object?
— Dan

Dear Dan,
Sounds good to me! I’d love such a system!
― Lennard

Dear Lennard,
I have been using the Park chain tool for years and recently started using a cog-wear tool. But how do you quantify chainring wear to know when to replace them?

We recently had problems with our tandem shifting from the middle 39t chainring to the 28t granny with both old and new chains, no matter how I adjusted the front derailleur. Replacing it with a new chainring cured the problem.
— Christian

Dear Christian,
There are two ways I do it visually. The first is to pull the chain straight away from the front of the chainring when it is engaged on the ring. If the chain pulls away significantly, especially to the point that you can see light under it, that chainring is toast.

The other way is to inspect the teeth. Being aluminum, they are soft, and when the teeth are worn, it is pretty obvious.
― Lennard

Dear Lennard,
I really enjoyed your article on testing for chain wear, but I think that for people who are not running friction labs, by far the best tool is the one you’ll use! For me that means my Park chain-wear tool, since it takes all of 30 seconds to measure wear.
— Mark

Dear Mark,
I agree. If it’s too much trouble to do it, one is not likely to measure their chain frequently enough to catch the chain wear in time to avoid ruining cogs. I use the tool that I find to be the quickest and easiest to use and that I feel also gives me a reasonably accurate relative measure. That is generally the ProGold tool, although I often use the Rohloff one as well; they yield similar results and are equally quick to use.
― Lennard

Dear Lennard,
Good article. I usually use a Park CC-2 and replace when the average of several measurements hits .50 (Campy 10s chains).

Re: variation in measurement, master links can really be different than the chains themselves. My experience with SRAM links is that they are noticeably longer, as measured, than links of the chain itself when used with Campy chains. On the other hand, KMC links are really tight — they actually make a click when going over the cassette.

I’m currently using a Wippermann link, which seems to work very well.
— Larry

Dear Larry,
That’s a surprising conclusion that SRAM master links are effectively longer when used on a Campy chain than the rest of the links in the chain. I’ve never endeavored to measure that, but I have often used SRAM links in Campy chains and never run into any problems doing so. I always check length in a number of different places on the chain, and I’d be surprised if I had never checked chain length over the master link, but I can’t say for sure.
― Lennard

Dear Lennard,
I had always regarded chain “stretch” to be a bit of a misnomer and thought it not so much a matter of the side plates getting longer as the rollers/pins wearing down and allowing each pair of side plates to be pulled incrementally farther away from their neighbors. I suppose it could instead be a matter of the roller/pins tearing larger holes in the side plates, yielding a similar result. If it is roller/pin wear rather than side plate tearing, might simply weighing the chain be a useful way to measure wear? Or do shavings adhere to the lubricant? Or perhaps the weights are too small and variances too high?
— Diren

Dear Diren,
Wow, that’s an interesting question. In practical terms, it would only be conceivable with a master link, because you’d have to remove the chain to do it. And I’m sure you’d have to clean and dry the chain very thoroughly before each measurement, because the weight differences you’d be looking for would be so small. So between those two things, you’re investing a lot of time into a measurement that can be done in seconds, albeit with questionable accuracy, with any of a number of chain checkers. I know I’d be unlikely to go to this much trouble to see if my chain needed replacing, but I’d be very interested to know if this method could be used to reliably check for wear.

My guess is that you’d be looking for fractions of a gram, so an extremely accurate scale would be a must, but I don’t know that. If you do pursue this, please let me know!
― Lennard

Dear Lennard,
Great article. I do have one question about the usefulness of the typical over-the-counter chain-wear checkers.

As I understand it, the “gold standards” for chain-wear checkers are the Shimano TL-CN40/41/42 and Pedro’s new-ish Chain Checker Plus — these designs all measure “true” chain wear in that they do not measure roller wear.

These are in contrast to the more commonly available chain wear tools (Park, Wippermann, KMC, Progold), which also include roller-wear when taking their measurement.

Do you agree that the latter tools are still “OK to use”? My intuitive sense is that the latter chain-wear indicators (since they also capture roller-wear) would have you tend to replace the same chain earlier (and, in general, more frequently) than the former “gold standards.” While not getting every last mile out of your chains, it isn’t bad for overall drivetrain health/performance/longevity to replace chains consistently a little early rather than a little late … yes?
— Walter

Dear Walter,
Yes, the latter, more standard chain checkers are less accurate than the Shimano or Pedro’s and would tend to indicate a chain that was worn sooner, rather than later. And, indeed, I would rather replace a chain too soon than too late.
― Lennard

Follow-up on vibrating road disc brakes from the author of the original question:

Dear Lennard,
Just wanted to follow-up on the latest development. Subsequent to your email, I took the bike to another LBS (shout-out to Bike Loft East in Manlius, New York) that provides support for all the local ‘cross races, and our state TT championship — great guys. They thought the issue was with the brake pads vibrating in the calipers, so they squirted some carbon paste between the brake pistons and the pads to keep the pads from sliding back and forth. After so much frustration and wasted time, I am happy to report that this simple/cheap fix works. I’ve had zero “thunking” when the brakes are applied; just great, smooth braking. I should add that my testing has been limited to several ‘cross rides covering approx. 30 miles total, plus a few washes.
— Nick