Bicycle Chain Length?

David has a very good question on how to know the correct length of your chain. We have been asked this before, but it’s a question that will always come up, we have two methods to discover this and here they are:

Question:
How do you know how long the chain should be, Do you go by sprocket size large chain ring?? Do you count the teeth too know how many links there should be. THANKS

Hi David.

If you are fitting a new chain it is very important to get the correct chain length as a long chain will hang down because the rear derailleur will not be able to take up the excess chain. If the chain is too short then you might not be able to use the large chain ring and larger sprockets. These are the methods:

Method 1:
Put the chain round the small chain ring and the small sprocket of the cassette and then feed the chain through the rear derailleur. By holding the ends of the chain, pull the ends of the chain together until the spring of the rear derailleur takes the strain and that’s where you need to cut the chain.

Method 2:
The preferred method of fitting a chain by Shimano is that you put the chain around the large chain ring and the large sprocket with out threading the chain through the rear derailleur, where the chain meets and then add two links and cut the chain at that point.

With both methods, remember to cut the chain so that you have an inner link meeting an outer link. Reconnecting the chain can be tricky, we have found that one of the quick link connectors are one of the best and cheapest methods.