Published September 1, 2010 11:34AM
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One of the most common oversights in bicycle maintenance is staying on top of chain wear.
This is especially true for the uneducated cyclist who may be new to the sport. That said, even guys like me who have more bike mechanic experience than they care to admit will sometimes forget to swap out a chain on occasion.
The result? Instead of simply replacing one of the least-expensive parts of the drivetrain and hitting the trail, a neglected, over-stretched chain will usually wear the cassette and chainrings to the point of incompatibility with a new chain, causing the need for an entirely new drivetrain.
While this oversight may prove a nice little stimulus plan for the local shop, it’s more money, mechanical work and missed trail time than needs to be spent.
Up until now the chain-stretch measuring tools used by both shops and consumers have been a bit on the gray side in regards to interpretation. They do work, but explaining to customers that they need to spend $80-plus on a new 10-speed chain because the wiggly little shop tool is reading “at this little line here if you push hard enough, and a good chain should only be reading at this line, which is here, right next to the bad line…” Well, you get the picture.
Old chain gauges have always left the door open for questioning accuracy and reliability of both the tool itself, and the tool operator. And without getting into design flaws of some of the chain-checkers out there, let’s just say that there are more than a few that have seen enough abuse in the shop to warrant replacement, but are still in service.
Apparently, Feedback Sports has been paying attention to the mediocrity of chain-stretch tools as well, as they recently dropped off one of their Feedback Chain Gauges for us to play with. We caught a glimpse of an early prototype of the tool last year at Interbike, so it wasn’t an entire surprise to see a production model show up on our desk.
And after almost a year of tweaking and polishing, with the help of chain manufacturer and producer of Feedback’s Chain Gauge, KMC, the production version is a go.
Like most chain-stretch measuring tools out there, the Chain Gauge works around the industry-standard of having exactly 1-inch/2.5mm between each roller. Essentially a modified digital caliper, the tool uses asymmetrical caliper jaws made of hardened stainless steel to plunge into the links for stretch measurement. One jaw features a semi-circle shape that is designed to cradle a roller as an anchor point, while the other jaw is shaped to slide in next to a roller eight links down.
Once in place, the spring-loaded jaws take the measurement and display it on a digital screen in either inch or millimeter format, down to the ten-thousandth or hundredth, respectively. The measurement can then either be read right on the
chain, or the jaws can be locked in place via a locknut, allowing the display to be read off the bike.
As for deciphering the number displayed, there is a simple conversion chart on the back of the tool that puts the measurement into one of three millimeter ranges: 0.00-0.40mm is good, 0.40-0.80mm is fair and anything over 0.80mm is bad. The gauge we received states on the front of the tool to replace if the displayed number is greater than 0.8mm, but according to Feedback, that can be considered inaccurate to some mechanics and will eventually be removed from production.
The tool uses a 1.5V watch-style battery, which is included along with both a spare battery and a small jeweler-style screwdriver to access the battery. There are three simple buttons on the device: On/Off, IN/MM, and ZERO. An auto shutoff kicks in at around five minutes to save battery life just in case the latter half of the On/Off switch is too complicated for you.
Pros: Shops will love the ability to give a definitive number from a precision tool to customers. And, with the tool’s spring-loaded jaws, the question of how hard the operator pushed on the tool to gain said measurement is thrown out the window.
The hardened, stainless steel jaws seem to be much less likely to bend like some of the narrow gauge pins used on other chain-checking devices, which again will help with accuracy, as well as negate an otherwise usual reason to buy a new tool.
The Chain Gauge worked extremely well on my entire quiver of bikes through three rotations of measurements, as it read to within one one-hundredth of a millimeter of accuracy on each bike all three times.
With a precision tool like this, it’s great that it comes with its own hard case. And both the extra battery and screwdriver for battery replacement are a nice touch, too. I also like the auto shutoff, as the amount of distractions in both my garage and the typical bike shop are usually more than enough to keep turning off little devices at the top of the to-do list.
Usually with an increase in precision, especially when digital readouts and buttons are involved, the complexity vastly increases as well. But with one push of the On button, it’s ready to measure. Of course, the Zero button was pushed once right out of the box, but it kept the same baseline throughout over 30 measurements, so I’m guessing zero’ing the tool is a one-time deal more often than not.
Cons: While the Chain Gauge would be a great addition to any bike shop, it’s a bit pricey for most consumers to justify having in their toolboxes.
The average mechanic’s line of sight to the chain is from up above, not directly from the side, so I think the display should have been set on top, or at least at an upward angle. The ability to lock the measurement into place and remove the tool to read is a nice option, and the display itself is easily readable, but this thing could have been that much cooler if the readout was more ergonomic.