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Chain Maintenance

Chain anatomy: To make a chain, we start with a skinny link, containing a pin inside a bushing held between two "inner side plates." Around the bushing, a roller turns freely as the chain contacts the teeth in your cogs. "Outer side plates" -- the fat links -- connect the two sets of inner side plates together, held in place by the pin.

chaincln.jpg (13221 bytes)
Keeping the chain clean avoids wear.
The moving parts of a chain wear out with time. Dirt and sand in the chain act like sandpaper to wear the chain down. As the parts lose close contact, the chain stretches. When the chain no longer fits correctly into the notches on your chainrings and rear cogs, it begins wearing them down. Plan to replace your chain yearly. It's cheaper than new chainrings!

A chain-cleaning tool helps scrub dirt and sand out of the links. Use it with a detergent or degreasing solution. If you ride long distances on muddy or dusty trails, the chain should be cleaned and relubed after every ride.

When cleaning the chain, also clean dirt and debris from the rear derailleur pulleys, rear cogs, and chainrings with a brush. Let the chain dry, then lube. Your choice of lube depends on your riding habits, time of year, and choice of trails:

lubes.jpg (16193 bytes) Chain wax (such as White Lightning, far left, and Pedro's second left, a thicker wax) is a "dry lubricant" that picks up very little dust and sand. But it provides no protection from rust if you're not able to dry the chain after a wet or muddy ride.

Thin oil (center) must be refreshed often, but it picks up less dirt than heavier oils or grease. It provides rust protection, but is more prone to gumming than chain wax.

Grease and heavy oil (such as tenacious oil, second right, and bearing grease, far right) are only appropriate for road riders. These heavy lubricants pick up dirt and sand, forming a "grinding solution" that wears your chain.
At the bottom is a degreaser, used to clean oil from the chain before reapplying lube. "Chain suck" is a dreaded condition where the chain hangs onto the bottom of the small or middle chainring as you pedal. It wraps up around the ring until it hits the incoming chain at the top of the chainring, then it locks everything up, bringing you to an abrupt stop. Keeping the chain clean and well-lubed helps avoid this problem. If it can't be traced to dirt, the problem may be worn teeth on the chainring, or a stiff chain. For an extensive discussion of the causes and treatment, see http://www.fagan.co.za/Bikes/Csuck/.
Depending on the amount of mud and dirt your chain encounters, your chain should be replaced every 500-1000 miles. A chain that has lengthened or has side-to-side looseness must be replaced.

Here's how to check your chain for excess wear:


While it's on the bike, you can put a metal ruler along the chain. Center an inch-mark on a pin, and see if the pins begin to "fall off" the inch mark.
Measure a length of chain containing 12 outer side plates. From the first pin of plate #1 to the first pin of plate #12 should measure exactly 12 inches. (Or, hold a new chain alongside the old chain to check for stretch.)
Put lateral stress on the chain (gently bend it sideways, or hold it so gravity makes it sag sideways). The chain should not have more than 2 inches of lateral sag over 12 inches of chain.

If the chain fails either of these tests, it should be replaced.

ch-brk02.jpg (15502 bytes) To be prepared for on-trail emergencies, you need a chain tool. And you need it WITH you, and you must know how to use it. We've saved several rides over the past year by fixing broken chains (or shortening the chain to bypass the rear derailleur after major disaster). See the section on chain repair.

A chain repair tool is included on many self-contained bike tool sets.

chainlnk.jpg (12632 bytes) I usually pack a "quick link" in my under-seat pack, because it gives a more trouble-free repair. But you need the right size. Quick-links are available for 7- or 8-speed chains (7- and 8-speed rear cogs use the same chain), and for 9-speed chains (9-speed chains are thinner). You still need a chain-breaking tool to get the old twisted outer side plates off the chain.

A "quick link" chain repair link can help avoid a long walk.

A breakaway pin is also nice to have. Again, it's specific to the size of chain you have (8-speed uses one size; 9 speed uses a narrower pin). This pin (along with a chain tool) lets you repair a broken chain, sometimes without loss of length. Refer to the new chain and chain repair sections for additional details.

See the wire? This is a home-made chain-clip, made from a hanger. It holds the ends of the chain together while you work on it.

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