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I put a new chain on the older bike, measured it up with the old chain, but did not change the cassette.

Unfortunately I am able to crank the pedals with the bike standing still on the ground with the chain making a noise.

Is that a sign for a cassette change or should I try to shorten the chain?

  • im not sure what you mean by "crank the pedals with the bike standing still on the ground " – Batman Apr 26 '15 at 0:52
  • As suggested below, the new chain should have the same number of links as the old one, not be the same length. After all, you are replacing it because it "stretched". But if you run with a "stretched" chain for too long the cogs wear prematurely. A good bike shop will be able to tell you (with a measuring tool) if the cogs are worn too far, or you can use the "lift test": Lift the chain off the cog. If you can lift it more than halfway off the teeth then the cog is too worn. – Daniel R Hicks May 26 '15 at 11:27
  • You should be able to tell if your cassette is too worn from a visual inspection. If you teeth are pointy then they worn too much. Take a look at this image. The teeth on the cog below the chain are worn from excessive riding in one gear, while the rest of the cogs seem to be in pretty good condition. As @DanielRHicks mentioned, you can take it to a bike shop to measure if you aren't sure, but if it's at the point shown in the picture, it's definitely time for a new one. – Kibbee May 26 '15 at 12:50
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As an old chain wears, the rollers get smaller and the chain settles deeper into the teeth of the gears. This results in more wear on the gears and, over time, the teeth will get pointier. Because the chain rollers are thicker on a new chain, it will sit higher on the teeth of the gears and when the teeth are worn enough the chain will slip.

Changing the length of the chain won't help. Contrary to popular belief, chains do not stretch significantly; the distance measured between the rollers is longer because the rollers become smaller as they wear. Past the .75 wear mark on a chain tool the gears will wear faster, at 1.0 the chain is at a higher risk of breaking.

The best solution for you at this time is to purchase and install a new cassette. Be certain to clean the chain and gears frequently to remove grit and metal shavings. Along with proper lubrication this should help keep the rear cassette in good condition longer.

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First of all, it's not right to measure new chain by old chain, as old chain stretched, and is longer than needed. Here (sheldon brown) you can find about chain length.
Does your chain skipping on some cogs, or at all the cogs? If it skips at some cogs, you should probably replace cassette. If it skips at all cogs, your chain probably bad or too long.

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For overall chain length (to decide on the number of links required when fitting a new chain) use published methods (eg wrap it over the two biggest cogs - not going through the rear derailleur, add two links to get the correct length - the count includes the joining link; this is the Shimano method for a double chainset but works fine for me with a triple).

Measure chain stretch due to wear with a chain wear indicator (cheap). If wear reaches 0.75 replace the chain. You should get through at least 3 chains before needing to change the cassette. Skipping on a few gears is a sign of a worn cassette - but can be a symptom of maladjusted rear derailleur (or maybe you put the cable the wrong side of the clamp bolt on the rear derailleur!)

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How do the cogs’ teeth look? Are some cogs’ really pointy?

Is it the first new chain?

Usually a cassette should last for several chains if you replace the chains in time and wear down the cogs evenly (i.e. don’t drive on the same cog all the time, especially the smaller ones which wear faster).

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Is it skipping across all gears or just a few?

If it's across all gears - and especially in the smallest (hardest to push) cogs - chances are the derailleur needs adjustment which is handled by the barrel adjuster (the knob on the back of the derailleur where the cable housing enters the derailleur).

Do this in small increments - 1/4 turn counter clockwise at a time. If the skipping gets worse start turning in the other direction (keep a count of how many 1/4 turns you make).

If adjustments at the barrel adjuster make no difference you could have a bent derailleur hanger (the small tab on the frame the rear derailleur bolts to). You'll need a special derailleur alignment gauge to fix this. Generally speaking, the more cogs you have in back the more finicky the drivetrain becomes.

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