4. How to Calculate Chain Length

Measure the correct length of a new bike chain.

IMPORTANT: Nuts and bolts on your bike should always be tightened to the manufacturer's specifications.
How to Calculate Chain Length
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When you purchase a new chain, it usually comes with extra length so that it is compatible with most drivetrains. How do you know how much length your bike will need? Well, it’s really quite simple…

The first step is to wrap the chain around the largest sprockets on the front and rear, so that the ends meet on the largest front chainring. For this step, it really important to not run the chain through the rear derailleur.

Next, position the chain on the chainring’s teeth at the tightest spot you could connect the chain. Now add one whole inner and outer link, so that you have approximately one extra inch of slack in the chain. That will be the optimal length for most systems.

In future tutorials I plan to discuss the different types of chain connectors and how to use a chain tool to break the chain. The following links provide some more helpful information.

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Hello all,

I have ridden my bike, a 1995 Mongoose Alta, for the past 20 years and replaced just about every component on it except for the frame, FD and front wheel. Gone through 3 RDs, several chains, rear hub, both shifters, etc. I'd estimate it's lasted at least 30k miles. I put road slicks on it and use it as my daily commuter, going 10 miles/day now. Love the bike!

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