Things You'll Need:
- Bike work stand or assistant
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Step 1
Place your bike up on a work stand to check the chain length, or have an assistant hold the rear up for you.
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Step 2
Know the hazards of an improperly sized chain. A bike chain that is too short is difficult to pedal and increases the wear on the cogs of your gears. A chain that is too long gives you sloppy power delivery and may slap your frame, damaging it; it could even jump off your drivetrain, causing an instant loss of power and possible damage to the bike.
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Step 3
Shift your bike to the physically smallest gears in both the front and the back. In the front, this is downshifting; in the rear, it is upshifting.
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Step 4
Examine the chain for play. The derailleur's chain tensioner should be able to take up all of the loose chain and retain tension on the section of bike chain between the bottom of the chainring and itself. If the derailleur is all the way back and the chain is touching itself or sagging, then it's too long.
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Step 5
Check the bike chain for shortness. Shift your bike to the largest chainring in the front and the second-largest cog in the rear.
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Step 6
Look at the chain where it passes into the pulley of the derailleur. There should be a very distinct "S" pattern to it. If there isn't, then your bike chain is too short.
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Step 7
Move your shifter slowly to the largest cog in the rear. If you're unable to see a distinct "S" bend in the chain or the chain begins to jam in the derailleur, then your chain is too short.
