Park CC-2 Chain Checker
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It doesn’t make any difference whether you pound a two-wheel machine against the rocks of the Sierra, slide through muddy twisties in the upper Midwest or power along the pancake-flat highways of the Gulf Coast, there is one thing that you will someday learn to be true: your chain gets infinitesimally more worn with every spin of the crank. I am fully prepared to bet that almost everyone who has ever taken a bicycle into the shop for that first-ever tune-up was told, “Your chain needs to be replaced.” More than a few of you also learned, “You probably need a new cogset, too…” |
Just what the aitch-e-double-hockey-sticks are they talking about??? Lemme ‘splain…
The chain transfers power from your motor (what non-cyclists call “legs”) to the rear wheel. A chain may look simple, but in reality it’s a pretty complex machine. It consists of links of a precise length fastened together with pins that double as axles. Each pin rides inside a roller that’s the same size as the troughs in the sprockets and chainwheels of the drivetrain. As the chain ages, the contact points of all those pins – there are 100 or so per chain on a atypical road bike – wear a little. As the pins wear, the chain gets just a wee bit longer.
That wouldn’t be a problem except that the rollers have to stay a precise distance apart to mesh with the teeth on the cogs correctly. If they get too far apart, they start wearing away the teeth – and that’s not a good thing. Replacing a worn chain can cost a few tens of dollars, replacing both chain and cogset will cost at least three times as much: the best price I’ve found for a replacement for my Shimano Ultegra cogset is well over $100; not to mention installation.
There are lots of varieties of chain-checkers: I have an old Park Tool CC-3.2, of the type called “Go-No Go”: if the gauge drops into a chain, the chain has stretched past a specific distance; if it doesn’t, the chain still has some life. I don't like the design, so I got myself a new one: a Park Tool CC-2, which actually measures chain stretch. It’s a small bar with one fixed pin and one moving pin. Slip the pins into gaps of the chain and adjust the movable pin. A gauge printed on the tool shows the mount of chain stretch. According to Park, if it’s more than 0.75% replace the chain.
The CC-2 is accurate and easy to use; plus I like that this version gives you a reading of the amount of stretch so you can estimate how much time you have before shelling out for a new chain. That’s a substantial improvement over the simple go-no go style of the CC-3 family. Though this version costs about three times as much as the chain checker I already had, I feel that the precision and accuracy make it worth the cost – especially as I’m maintaining four road bikes and recently de-mothballed a pair of ancient hybrids.
| My recommendation? Anyone who owns a bike and does even the most rudimentary maintenance should have a chain checker; and this one is an excellent investment in the future of your bike. A parting note: It gets more complicated: true purists point out that chain checkers of this style and that of the CC-3.2 add the wear on the rollers, which is immaterial, to the wear on the pins – so these checkers always overestimate wear. That may be why three times in the past couple of years bike mechanics told me I’d need a new cogset, and three times the bike came home with the old one. So if this checker reads 0.50, you’re probably not really there yet. Those purists stick with the ruler method, though that seems fraught with inaccuracy to me… |
Summary
PLUS: More accurate and precise than go-nogo checkers
MINUS: still includes roller wear in "stretch"
WHAT THEY'RE SAYING: Take a step up from simple go-no checkers and actually measure chain stretch with a Park Tool CC-2 chain checker.
copyright © 2018 scmrak
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