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After reading on here that if you hold a 12" ruler up to your chain with one end in the center of a chain pin, and the pin at the other end is 1/8 of 1" or more from that end of the ruler, and this was the case with my chain, I decided I wanted to get a new one. Besides, I was having a really hard time getting it perfectly clean this time (keeps making gritty noises) and i've had some slow / hesitant shifting even though derailluers are in tune. Signs of a worn chain, right?

I didn't have my bike with me for him to look at, but from my symptoms the guy at the local LBS told me I didn't need to buy a new chain yet. He suggested I just clean the old one up as good as I can, and wait until the chain skips around while just pedaling. He also said that I will need to replace my cassette when I do put the new chain on, as a new chain and used cassette just won't work well together (regardless of how it looks- but mine looks great).

I like to keep my bike running well. Chains are pretty cheap, cassettes are pretty expensive. What do you guys think?
 

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bender said:
I like to keep my bike running well. Chains are pretty cheap, cassettes are pretty expensive. What do you guys think?
If the chain is very badly worn, the cassette is gone as well. Replace the chain, if it skips on the old cassette, you must replace the cassette too. If not, you're good to go. If you wait too long, the worn chain will wear the chainrings too, and the cost keeps going up.
 

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poor advice..

Place the ruler at the edge of a pin. When new, the pin at the opposite end will be completely covered. If 1/2 of the pin at the opposite end is showing, you have more than 1/16 inch elongation and the chain needs replaced.

A worn chain will not start skipping. It just continues to wear-in to match the cogs. Wait long enough and the cogs will be unuseable with a new chain.

You may have already waited too long. If you install a new chain and it skips under a heavy load, in just a few of the most heavily used cogs, then the cassette is also worn out.
 

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Sounds like he's at the point of no return

C-40 said:
Place the ruler at the edge of a pin. When new, the pin at the opposite end will be completely covered. If 1/2 of the pin at the opposite end is showing, you have more than 1/16 inch elongation and the chain needs replaced.

A worn chain will not start skipping. It just continues to wear-in to match the cogs. Wait long enough and the cogs will be unuseable with a new chain.

You may have already waited too long. If you install a new chain and it skips under a heavy load, in just a few of the most heavily used cogs, then the cassette is also worn out.
If the wear is in fact close to 1% (1/8"), then you can just ride it out until it begins skipping and replace both chain and cassette together. The prudent person would replace both immediately, but it's a toss-up at this point IMO. If this is the bike's first chain, then there is probably a small amount of wear to the chainrings but likely not enough to cause any problems. I've made this recommendation to customers before, although it's usually a POS mountain bike and the customer is reluctant to pay the money for the replacement parts (possibly because they don't think anything is really wrong, since the chain hasn't begun skipping at that point). Replacing right before or at .5% (1/16") generally gets the most life out of the chain with minimal wear to the cassette.
 

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You read wrong

bender said:
After reading on here that if you hold a 12" ruler up to your chain with one end in the center of a chain pin, and the pin at the other end is 1/8 of 1" or more from that end of the ruler, and this was the case with my chain, I decided I wanted to get a new one.
That was "the rule" back in the 7 speed (and less) days, and typically by that point you would have worn out one or two cogs as well such that a new chain would skip on those worn cogs. Since 8 speed came out, the tolerances were tightened to the 1/16" elongation (0.5%). Even with this more conservative approach, if you ride most of the time in one or two cogs, you might have to replace at least those cogs. With 1/8" elongation on a modern chain, you probably have worn cogs that will result in chain skip. Replace the chain and if you don't get chain skip under load, you're good to go.
 

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Kerry Irons said:
That was "the rule" back in the 7 speed (and less) days, and typically by that point you would have worn out one or two cogs as well such that a new chain would skip on those worn cogs. Since 8 speed came out, the tolerances were tightened to the 1/16" elongation (0.5%). Even with this more conservative approach, if you ride most of the time in one or two cogs, you might have to replace at least those cogs. With 1/8" elongation on a modern chain, you probably have worn cogs that will result in chain skip. Replace the chain and if you don't get chain skip under load, you're good to go.
I think this is the best advice. I would only add that you definately should get a new chain and if you ride and have a skipping problem with the new chain, then definately get a new cassette. It's a good lesson to learn. You do, as others have said, get the longest life out of your drivetrain if you replace the chain before it exceeds 0.5% elongation. On the other hand, if you continually clean the chain, you can continue to ride your bike without skipping problems. Eventually your drivetrain will be so worn that you will end up having to chainge the cassette, chainrings and chain all in one shot. That can seem pretty expensive on a cheaper bike, though. Worth it if you are happy with your bike.If it's over half the cost of a new bike, then you might consider that as well.
 
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