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.
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:
||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
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.
||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
||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.
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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