Words by: Max Morgan
For this MTB How To, we are going to be focusing on setting the correct chain length when installing a new mountain bike chain on a 1X drivetrain. Making sure your chain is set to the correct length is crucial in the performance of the drivetrain system. If the chain is too long, the derailleur may not be maintaining the proper tension of the chain in harder gears (smaller gears). If you are riding a full suspension bike and the chain is too short, as you go through the suspension travel, the chain may exceed the movement of the derailleur arm itself. This may limit using your bike's full travel and may break the chain and derailleur in the process.
Here we will be installing a SRAM PC XX1 11-speed chain on SRAM's XO1 DH 7-speed drivetrain. SRAM's 7-speed and 11-speed offerings use the same chain. To get the job done correctly, you will need the new chain, a chain breaker, and chain link pliers. A pair of needle nose pliers may also work in removing the chain quick link if careful. I will be using a Park Tool CT-5 Compact Chain Tool and a pair of Bike Hand Master Link Pliers.
Use the Master Link Pliers to remove the old chain. If your chain uses a Shimano pin system and doesn't have a quick link, use the chain breaker tool to remove any one of pins to disconnect the chain.
If you replacing a worn out chain, it might be time for a new cassette and chainring as well. This is also a great time to make sure your existing drivetrain is clean and free of gunk. If you are building a new bike, install the cassette, chainring, chain guide and rear wheel in the bike before sizing the chain.
Start by shifting the derailleur into its smallest gear (meaning bottom gear farthest from the hub). Next, take one end of the chain and run it through the top of the front chainring. Then take the other end of the chain and feed it through the cassette's smallest gear and derailleur. This will leave you with both open ends of the chain below the chainstay as shown here.
Keep in mind some chains are directional. SRAM chains are not directional but with Shimano, the engraving on the chain must be facing outwards from the bike.
Everyone seems to have a different trick for sizing your chain correctly. Once you have your chain through the front chainring and in the lowest gear through the derailleur, you can decide how many links need to be removed from the stock length. All chains come longer than they need to be to accommodate all different styles and sizes of bikes.
Grab both free ends of the chain and pull them towards each other. With the chain in your left hand, pull a small amount of tension on the derailleur arm. Your best bet for sizing the chain correct is to find the first available link while the derailleur is slightly tensioned in its lowest gear.
Remember that the SRAM quick link is the wider portion of the chain link. This means that you are trying to find the first available narrow portion of the chain for the quick link to slot through. In the first photo below you can see what pulling the chain taught looks like. In the second photo, you will see the red arrow points towards the first available pin to remove while incorporating the quick link.
Make note of which pin needs to be removed, grab your chain breaker, and push the pin all the way out of the chain removing the excess chain length.
Most recent SRAM derailleurs feature what they call Cage Lock. Using the small lock button, push the derailleur forward and lock it into place. This will make installing the chain and also removing the wheel from your bike much easier.
While SRAM's chains are not directional, THE SRAM QUICKLINK IS DIRECTIONAL. If you look closely you will see an arrow engraved into the face of the quick link. This arrow should put in the direction the chain is moving. Make sure to get this arrow pointing the right way to avoid any chain skipping.
Here is one trick to snap the quick link into place. First push the quick link together with your fingers. Then pedal the chain and quick link through the derailleur and leave the quick ling in between the chainring and cassette above the chainstay. Hold the rear brake lever closed and pedal the cranks forward while leaving the bike in the stand. You should hear the quick link snap into place!
When installing a Shimano chain, use the chain breaker to push the new pin through the connecting links. Once the pin is flush on the outside face of the chain, use your needle nose pliers to break off the smaller portion of the pin.
Make sure the chain is shifting smoothly between gears. Work your way up into the highest gear to make sure the chain isn't going to be too short. The bike used here is a Santa Cruz V10 which does experience a good amount of chain growth.
One way to ensure the chain is not too short is to cycle the bike through its suspension travel without limiting the derailleur. Either remove the air from your air shock or remove the spring off of your coil shock and then re-install the shock on the bike. Cycle the bike through its suspension travel in its highest gear, and if the chain does not limit the suspension travel, you are all good to go!
This article was written / authored by Max Morgan. Max has been a professional downhill mountain bike racer for the last 10 years, competing in the UCI World Cup downhill series and U.S. Pro GRT series. Having ridden all different kinds of bikes on trails all over the world, Max's experiences being out on the circuit give him a unique perspective on what makes for a quality cycling component. Max also has degrees in Mechanical Engineering and Physics, and so if you don't see out on the trail, chances are he is probably in the garage tinkering on the next project.