How do You Know you have the right chain length?
10-01-07, 08:23 PM
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How do You Know you have the right chain length?
I just replaced my chain w a Dura-Ace chain and nee Ultegra casssette. I have a compact with a 12-27 Ultegra. New chain has 116 links...old had like 106...I took 5 off the new.
Now shifting on the rear cassette is violent, not smooth..wondering how I can know chain length is OK and start focusing on other sources...BTW all original cables with around 4K miles.
Now shifting on the rear cassette is violent, not smooth..wondering how I can know chain length is OK and start focusing on other sources...BTW all original cables with around 4K miles.
10-01-07, 08:27 PM
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10-01-07, 08:31 PM
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The best way to determine chain length is the "large/large" method, where you take the chain and run it over the largest cog, without running it through the rear derailleur, and also over the largest chainring, with the end of the chain on the large chainring. Find the point on the other end of the chain where you would have enough length to connect the two, and then add one full length to that (one inch)-
Last edited by well biked; 10-01-07 at 08:40 PM.
10-01-07, 08:38 PM
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From the Park Tool Website:
Chain Sizing by Equation
Bicycle chains consist of inner and outer plates. It is only possible to join inner plates to outer plates. Because of this, chains can only be connected at whole (integral) inch increments. For example, some derailleur bike chain could only be 51, 52, 53 inches, etc. Chains cannot be cut to 52-1/4”, 53-1/8”, or even 52-1/2”. It is possible to determine chain length from industrial drive train equations, and then cut the chain before installing it on the bike.
Begin by counting the number of teeth on the largest front sprocket and largest rear. These numbers are often printed right on the sprockets and cogs. Next, measure the distance between the middle of the crank bolt to the rear axle. This is also the chain stay length. Measure to the closest 1/8”, and convert this to decimal form. A simple chart below will assist this conversion.
SIMPLE EQUATION: L = 2 (C) + F/4 + R/4 + 1
L = Chain length in inches. Round the final result to closest whole inch figure.
C = Chain stay length in inches, measure to closest 1/8”. Use chart below to find decimal measurement.
F= Number of teeth on largest front chainring.
R= Number of teeth on largest rear cog.
Example: A bike has a 42-32-22 front chainring set up. Use only the 42 for the equation. The rear cog set has 32 tooth largest cog. The bike measures 16-3/8” from the center of the rear axle to the center of the crank bolt. The decimal equivalent for 16-3/8” is 16.375 inches.
L = 2 (16.375) + 42/4 + 32/4 + 1In the example above, this becomes 32.75 + 10.5 + 8 + 1 = 52.25 inches. Chains cannot be joined at 52.25 inches, so this length is rounded to 52 inches.
For this system, round up from 0.5. For example, a chain length figured to be 55.5 would be rounded to 56 inches.
To measure the new chain, lay it on a flat surface with the rollers and plates aligned vertically. Pull on each end to straighten out the chain. Measure from either end. Remember, you can only shorten the chain at whole inch increments. If the chain uses a master link, install it on one of the chain for purposes of measuring, and measure including the master link.
Chain Sizing by Equation
Bicycle chains consist of inner and outer plates. It is only possible to join inner plates to outer plates. Because of this, chains can only be connected at whole (integral) inch increments. For example, some derailleur bike chain could only be 51, 52, 53 inches, etc. Chains cannot be cut to 52-1/4”, 53-1/8”, or even 52-1/2”. It is possible to determine chain length from industrial drive train equations, and then cut the chain before installing it on the bike.
Begin by counting the number of teeth on the largest front sprocket and largest rear. These numbers are often printed right on the sprockets and cogs. Next, measure the distance between the middle of the crank bolt to the rear axle. This is also the chain stay length. Measure to the closest 1/8”, and convert this to decimal form. A simple chart below will assist this conversion.
Fractional conversion to decimal for 1/8” measurements:
1/8” = 0.125”
1/4" = 0.25”
3/8” = 0.375”
1/2” = 0.5”
5/8” = 0.625”
3/4" = 0.75”
7/8” = 0.875”
For most bicycles, a relatively simple chain length equations may be used. For bicycles with extreme differences in chainring sizes and short chain stays, the more rigorous and complete equation may be used. This is discussed later in this article. 1/8” = 0.125”
1/4" = 0.25”
3/8” = 0.375”
1/2” = 0.5”
5/8” = 0.625”
3/4" = 0.75”
7/8” = 0.875”
SIMPLE EQUATION: L = 2 (C) + F/4 + R/4 + 1
L = Chain length in inches. Round the final result to closest whole inch figure.
C = Chain stay length in inches, measure to closest 1/8”. Use chart below to find decimal measurement.
F= Number of teeth on largest front chainring.
R= Number of teeth on largest rear cog.
Example: A bike has a 42-32-22 front chainring set up. Use only the 42 for the equation. The rear cog set has 32 tooth largest cog. The bike measures 16-3/8” from the center of the rear axle to the center of the crank bolt. The decimal equivalent for 16-3/8” is 16.375 inches.
L = 2 (16.375) + 42/4 + 32/4 + 1In the example above, this becomes 32.75 + 10.5 + 8 + 1 = 52.25 inches. Chains cannot be joined at 52.25 inches, so this length is rounded to 52 inches.
For this system, round up from 0.5. For example, a chain length figured to be 55.5 would be rounded to 56 inches.
To measure the new chain, lay it on a flat surface with the rollers and plates aligned vertically. Pull on each end to straighten out the chain. Measure from either end. Remember, you can only shorten the chain at whole inch increments. If the chain uses a master link, install it on one of the chain for purposes of measuring, and measure including the master link.
10-01-07, 09:09 PM
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From the Park Tool Website:
Chain Sizing by Equation
Bicycle chains consist of inner and outer plates. It is only possible to join inner plates to outer plates. Because of this, chains can only be connected at whole (integral) inch increments. For example, some derailleur bike chain could only be 51, 52, 53 inches, etc. Chains cannot be cut to 52-1/4”, 53-1/8”, or even 52-1/2”. It is possible to determine chain length from industrial drive train equations, and then cut the chain before installing it on the bike.
Begin by counting the number of teeth on the largest front sprocket and largest rear. These numbers are often printed right on the sprockets and cogs. Next, measure the distance between the middle of the crank bolt to the rear axle. This is also the chain stay length. Measure to the closest 1/8”, and convert this to decimal form. A simple chart below will assist this conversion.
SIMPLE EQUATION: L = 2 (C) + F/4 + R/4 + 1
L = Chain length in inches. Round the final result to closest whole inch figure.
C = Chain stay length in inches, measure to closest 1/8”. Use chart below to find decimal measurement.
F= Number of teeth on largest front chainring.
R= Number of teeth on largest rear cog.
Example: A bike has a 42-32-22 front chainring set up. Use only the 42 for the equation. The rear cog set has 32 tooth largest cog. The bike measures 16-3/8” from the center of the rear axle to the center of the crank bolt. The decimal equivalent for 16-3/8” is 16.375 inches.
L = 2 (16.375) + 42/4 + 32/4 + 1In the example above, this becomes 32.75 + 10.5 + 8 + 1 = 52.25 inches. Chains cannot be joined at 52.25 inches, so this length is rounded to 52 inches.
For this system, round up from 0.5. For example, a chain length figured to be 55.5 would be rounded to 56 inches.
To measure the new chain, lay it on a flat surface with the rollers and plates aligned vertically. Pull on each end to straighten out the chain. Measure from either end. Remember, you can only shorten the chain at whole inch increments. If the chain uses a master link, install it on one of the chain for purposes of measuring, and measure including the master link.
Chain Sizing by Equation
Bicycle chains consist of inner and outer plates. It is only possible to join inner plates to outer plates. Because of this, chains can only be connected at whole (integral) inch increments. For example, some derailleur bike chain could only be 51, 52, 53 inches, etc. Chains cannot be cut to 52-1/4”, 53-1/8”, or even 52-1/2”. It is possible to determine chain length from industrial drive train equations, and then cut the chain before installing it on the bike.
Begin by counting the number of teeth on the largest front sprocket and largest rear. These numbers are often printed right on the sprockets and cogs. Next, measure the distance between the middle of the crank bolt to the rear axle. This is also the chain stay length. Measure to the closest 1/8”, and convert this to decimal form. A simple chart below will assist this conversion.
Fractional conversion to decimal for 1/8” measurements:
1/8” = 0.125”
1/4" = 0.25”
3/8” = 0.375”
1/2” = 0.5”
5/8” = 0.625”
3/4" = 0.75”
7/8” = 0.875”
For most bicycles, a relatively simple chain length equations may be used. For bicycles with extreme differences in chainring sizes and short chain stays, the more rigorous and complete equation may be used. This is discussed later in this article. 1/8” = 0.125”
1/4" = 0.25”
3/8” = 0.375”
1/2” = 0.5”
5/8” = 0.625”
3/4" = 0.75”
7/8” = 0.875”
SIMPLE EQUATION: L = 2 (C) + F/4 + R/4 + 1
L = Chain length in inches. Round the final result to closest whole inch figure.
C = Chain stay length in inches, measure to closest 1/8”. Use chart below to find decimal measurement.
F= Number of teeth on largest front chainring.
R= Number of teeth on largest rear cog.
Example: A bike has a 42-32-22 front chainring set up. Use only the 42 for the equation. The rear cog set has 32 tooth largest cog. The bike measures 16-3/8” from the center of the rear axle to the center of the crank bolt. The decimal equivalent for 16-3/8” is 16.375 inches.
L = 2 (16.375) + 42/4 + 32/4 + 1In the example above, this becomes 32.75 + 10.5 + 8 + 1 = 52.25 inches. Chains cannot be joined at 52.25 inches, so this length is rounded to 52 inches.
For this system, round up from 0.5. For example, a chain length figured to be 55.5 would be rounded to 56 inches.
To measure the new chain, lay it on a flat surface with the rollers and plates aligned vertically. Pull on each end to straighten out the chain. Measure from either end. Remember, you can only shorten the chain at whole inch increments. If the chain uses a master link, install it on one of the chain for purposes of measuring, and measure including the master link.
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10-01-07, 09:22 PM
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10-01-07, 10:38 PM
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I recently replaced the chain on my triple with 9-speed rear cluster. Shifting had no problems before, but a few bugs afterward. Tweaking the barrel adjusters took care of it. I just shortened the new chain to the same length as the old chain and everything was fine. Maybe I do not understand your problem.
