In this video we'll cover how to install a chain on a two-sprocket drivetrain.
We'll cover sizing, installation, and tension.
Hi I'm Ben with Park Tool.
People like the simplicity of two-sprocket drive trains like BMX, fixed-gear single speeds, or old-style cruisers.
You may also also find them on internally geared hubs.
Typical Tools and supplies include a wrench to remove and install the axle nut - typically 15mm,
a torque wrench to properly secure the axle nut,
a needlenose pliers for the master link,
and a chain tool.
The Park Tool CT-3.2 has a floating shelf, which is useful as many single speed chains are thick,
and some other chain tools may not fit.
Before we get started, we'll remove the old chain from the bike.
Loosen the axle nuts to relieve tension on the chain.
Use a needle nose pliers to remove the c-clip and masterlink.
Then remove the chain.
Some two-sprocket chains may use a different type of masterlink similar to those found on derailleur chains.
Disengage this masterlink using a masterlink pliers.
If you don't see a master link, your chain uses a connecting rivet.
If you have this type of chain, skip to the time shown for instructions.
If your old chain was properly sized,
simply lay it next to the new chain on a workbench and match the rivets side-by-side to get your length.
We'll cut the chain at this rivet.
Now we'll show you how to size a change from scratch.
For horizontal dropouts, place the axle all the way forward in the dropout slot.
With forward facing dropouts, secure the axle nuts so they are fully engaged in the dropouts but as far forward as possible.
Wrap the chain around the front and rear sprockets.
Place the chain end on the front ring at about the two or three o'clock position.
Engage any master link to account for all the links when determining chain length.
Pull the chain as tight as you can, noting that the outer plate must attach to the inner plate.
There may be some slack.
Ideally, the chain ends will meet at an inner and outer plate as shown here.
We'll call this rivet the reference rivet.
It's possible that two outer plates will meet as shown in this example.
Here, we'll add one pin so the appropriate chain ends meet.
This is the reference rivet.
From the reference rivet, we'll add two more pins, or one inch, to the chain length.
We do this because the extra inch will provide enough slack
to allow the chain to be lifted from the ring for wheel removal.
It also adds more flexibility for larger tires.
Make note of the appropriate rivet to remove, to shorten the chain.
Use a chain tool such as the CT-3.2 to remove the rivet.
With the chain correctly routed through the frame, join the ends of the chain.
Pull the wheel back in the dropouts and align the wheel centered between the chainstays.
Snug the axle nuts, but don't fully tighten as we need to check the chain tension first.
As a safety precaution, only touch the outer perimeter of the chain.
Many mechanics have at least one story where someone caught a finger on the inside.
To check the tension on the chain, push the chain downward and upward in the middle.
There should be approximately one half inch or 12mm of movement in the chain up and down
at a point halfway between front and rear sprockets.
This example is too loose. You can see the sag in the chain as the bike is pedaled.
This example is too tight. Listen to the sound of the chain as it binds against the rear cog.
To change the tension, loosen one of the axle nuts and move the wheel forward or backward slightly.
Snug it up again.
Then loosen the other nut, adjust and tighten, making sure the wheel is centered in the frame.
Re-check the tension.
A chain tensioner can make the process easier.
Tightening this screw puts tension on the chain.
We make sure the wheel is centered in the frame and set our tension.
Then we tighten the axle nut here...
and finally on the other side.
If the tension looks adequate, we'll now turn the crank and check the tension again.
If you see loose and tight spots as the sprocket turns, it means your sprockets are out of round.
This is not uncommon, just set the chain to have 1/4 inch of movement at the tightest spot.
A final test is applying sideload on the chain at a point in between the front and rear sprockets.
The chain will make a rattling sound, but should not derail.
If the chain comes off either the front or rear sprocket, increase tension and test again.
If the chain stays on, fully secure the axle nuts to manufacturer recommended torque,
typically around 25 Newton meters
With a hand wrench, use percieved effort.
For 25 Newton meters, apply about 40 pounds of effort holding the wrench 5" from the axle.
Finally, if the bike uses a coaster brake or a band brake, secure the brake arm to the bike frame.
And that's it for two sprocket chain installation.
Remember, a clean bike is a happy bike so don't miss our video on chain cleaing and lubrication.
See The Park Tool Guide to Chains to get a quick snapshot of our other chain related videos.
Thanks for watching.
This next segment is for those with connecting rivet chains.
A connecting rivet chain has no master link. Instead it is connected using a special connecting rivet.
It'll look slightly different than the rest of the rivets.
First we're going to walk you through a couple procedural differences if you have this type of chain,
then we'll send you back to where we left off, and you'll follow along with the master link chain people.
But really, the only difference is in connecting and disconnecting the chain.
To disconnect the chain, choose a rivet that is not a connecting rivet and drive it fully out of the chain.
Remove the chain tool from the chain and then remove the chain from your bike.
To connect your correctly sized and cut chain, Lubricate the connecting rivet.
Install the rivet into the chain, from the inside of the bike toward the mechanic.
Install the chain tool.
Drive the connecting rivet into the chain.
So as the the pilot goes through and as you initially start to bring the pin through the chain,
you'll feel a little resistance, and the resistance will kind of let off.
You can then just push the pin all the way in
and then you'll feel the resistance start to ramp up as the pin starts to go through the outside plates.
You can feel it, there's a dead stop, and that's where you want to kind of back off
and then you can look to see where the protrusion is,
and if it's equal on both sides of the chain, that means it's good.
You're then ready to break off the pilot and your chain's installed.
Break off the pilot tip of the connecting rivet using the chain tool, or pliers.
the chain tool or pliers pedal the bike
Pedal the bike and inspect for tight links.
If you find one, flex the chain back and forth with your hands to loosen it.
Now just scrub back to the time shown, and follow along.
The sizing and tension procedures are the same regardless of your chain type.
Thanks again for watching, and remember: keep the rubber side down.
Thanks for watching this repair help video from Park Tool.
We're constantly adding to our repair help library,
so like and subscribe to get all the latest content from Park Tool