How to Remove and Replace the Freewheel Cogs

The Freewheel cogs belong to the hub in one of two ways. Newer bikes tend to use a type hub called a “cassette hub.” The cassette hub takes a “freehub” system, which is a type of clutch mounted to the hub body. This cylindrical mechanism ratchets in a counter-clockwise direction for coasting, and locks in the clockwise direction to impulse the bike when pedaling. The freehub body has serial splines on the outer shell. “Cassette” sprockets slide over these splines. Lock ring threads into the freehub and stays the sprockets or cogs, in place. When the cogs are taken off, the freehub stays on the body of the hub. Actually, in this modern time, many bikes take the freehub system. When the cogs and the ratcheting body assembly, it is called a “freewheel,” which threads onto the hub. The ratcheting mechanism removes together with the cogs while freewheel unthreads for removed.



Ready:

It should depend on the style of the hub, the style or brand of cogs, and according to these, find the removal tool required. The removal tool must fit the part correctly; otherwise, these two components may become damaged.
With the modern cassette cog systems, the cogs are tailored with splines. Cogs slide onto the freehub body and are held in place by a lock ring. The lock ring is on the outward side from the smallest cog. Turn the lock ring to loosen it in the counter-clockwise direction, the opposite way of the arrow. It generates a noise when the lock ring becomes loose. There is often knurling under the lock ring, helping keep it in the right operation, and this knurling also come out a noise when the ring is loosened or tightened.
Removing the freewheel cogs

Remove the quick-release skewer.
Check cassette and choose the right type of cogs.
Engage remover into splines and notches.
Install quick-release skewer and install skewer nut on outside the remover.
Tighten skewer nut by remover. Skewer works as a holding device for removing the freewheel.
Keep cogs clockwise with sprocket chain whip tool, meanwhile turn the remover counter-clockwise with a large adjustable wrench, the hex end of another Park Tool sprocket chain whip toolSR-1 or the Park Tool freewheel wrench FRW-1. It needs the force to remove the lock ring. And then you are expected to hear a loud sound of clack as the locking teeth of the lock ring separate.
If using a vise, you should grab removal tool tightly with wheel held flat. Use sprocket chain whip tool to turn sprockets in the counter-clockwise direction. Do not hold the wheel while turning sprockets, you need to allow the wheel to rotate and pull only on sprocket chain whip tool.


Replacing the Cogs

Check the splines on the freehub body. Find out a wide space between splines. Check the internal splines of cogs. Find out a wide spline to match with a wide space in free hub body. Line splines and engage all cogs.
Install spacers in the same direction as removing direction.
Put grease threads of the lock ring and thread lock ring into the freehub.
Place the cassette lock ring tool and install quick-release skewer, and then thread skewer nut on outside of lock ring tool.
Tighten skewer nut by remover. Skewer works as a holding device for removing the freewheel.
Turn remover clockwise until lock ring is tight, at least 360 inch-pounds (approximately 40 Nm). There is no need to use the sprocket chain whip tool for replacing the lock ring.
You will need to determine the style of hub you have and the style or brand of cog system. When remove and install the old model freewheels where the tool is no longer available, it still is possible to reuse the wheel. However, it will need to destroy freewheel. There are not many adequate designs for removing the current models of freewheels.



Installing the older freehub cogs

To install the older freehubs may lack notches or splines next to the axle. These older freehub cogs did not need the tools for freewheel or cassette lock ring removal. There will be a dust cap for the hub on the right side, but no recessed notches or lock ring splines at all. The first cog acts as a lock ring for the other cogs.

Tool: Two Sprocket Chain Whip.

Step 1: put the sprocket on the second or third cog, turning it clockwise.

Step 2: place the second sprocket tool on the first cog and then make the counter-clockwise rotation.

Step 3: Form a “V” shape by sprocket tools. This helps you get a better mechanical advantage.

Step 4: Rotate the first cog in the counter-clockwise direction at the same time holding the second sprocket chain whip tool. It is to loosen the first cog. Afterward, remove a cog and pull off other cogs.