Cassette and Freewheel Removal and Installation
This article will review the removal and installation of rear cogs on derailleur type bicycles as well as single speed freewheeling BMX/Freestyle bikes.
The rear cogs are attached to the hub in one of two ways. Newer bikes tend to use type hub called a “cassette hub.” The cassette hub uses a “freehub” sytem, which is a type of clutch mounted to the body of the hub. This cylindrical mechanism ratchets counter-clockwise for coasting, and locks clockwise for driving the bike when pedaled. The freehub body has a series of splines on the outer shell. “Cassette” sprockets slide over these splines. A lockring threads into the freehub and holds the sprockets, or cogs, in place. When the cogs are removed, the ratcheting freehub remains on the hub body. Most modern bicycles use the freehub system. See a typical cassette hub below.
Older bikes may have a large external thread machined into the hub. The cogs and ratcheting body assembly, called a “freewheel,” threads onto the hub. The ratcheting mechanism comes off with the cogs when the freewheel unthreads for removed.
To remove rear cogs, begin by determining the style of hub, the style or brand of cogs, and the removal tool required. The removal tool must fit the part correctly, or both may become damaged. After removing the wheel, look at the flat surfaces adjacent to the right rear axle for brand names.
Freewheel Tool Compatibility
You will need to determine the style of hub you have and the style or brand of cog system. The table below shows several different options.
|Shimano® freewheel, Sun Race®, Sachs®||12 splines, approx. 23mm diameter
|Suntour® two-notched||2 notches, 25mm across|
|Suntour® four-notched||4 notches, 24mm across|
|Atom®, Regina®, some Schwinn®-approved||20 splines, 21.6mm across|
|FR-5.2, FR-5.2G, FR-5GT, FR-5H|
|Shimano® cassette, SRAM®, Chris King®, Sun Race®, Hugi®, etc.||12 splines, approx. 23.4mm across|
|Single speed & BMX freewheels||4 notches, 40mm across|
|Falcon® freewheels||12 splines, approx. 23mm across|
|Compact single speed (30mm thread / “flip-flop hubs”)||4 notches, 32mm across|
|Campagnolo® (cassettes only, not freewheels)||12 splines, approx. 22.8mm across|
There are older model freewheels where the tool is no longer available. It may still be possible reuse the wheel but it will require destroying the freewheel. There are also current models of freewheels that do not have an adequate design for removal. In the image below, the freewheel has two very narrow and shallow notches that do not allow enough purchase for a tool. Removal of this type of freewheel would likely result in ruining any both the freewheel and the tool. For either situation, see destructive removal of freewheels.
Cassette Cog Lockring Removal
Shimano®, Campagnolo®, Sun Tour®, Sun Race®, Chris King®, DT-Hugi®, and other brands
If your cogs look like this, you probably have a lockring type cassette.
With the modern cassette cog systems, all cogs are fitted with splines. Cogs slide onto the freehub body and are held in place by a lockring. The lockring sits outward from the smallest cog. Look for the word, “LOCK”, and an arrow on the lockring indicating direction to turn for locking. Turn the lockring counter-clockwise, the opposite way of the arrow, to loosen it. There may be a loud noise when the lockring breaks loose. There is often knurling under the lockring to help keep it in place, and this knurling makes noise when the ring is loosened or tightened.
Mount bike in repair stand and remove rear wheel from bike.
- Remove quick release skewer.
- Inspect cassette and select correct type of remover.
- Engage remover into splines/notches.
- Install quick release skewer and install skewer nut on outside of remover.
- Snug skewer nut against remover. Skewer acts as a holding device for freewheel removal tool.
- Hold cogs in clockwise direction with sprocket chain whip tool. Turn remover counter-clockwise, using a large adjustable wrench, the hex end of another Park Tool sprocket chain whip tool SR-1, or the Park Tool freewheel wrench FRW-1. It will require force to remove the lockring. Expect to hear a loud clicking sound as the locking teeth of the lockring separate.
- If using a vise, grab removal tool tightly in vise with wheel held flat. Use sprocket chain whip tool to turn sprockets counter-clockwise, as seen from above the hub. Do not hold wheel while turning sprockets, allow wheel to rotate, and pull only on sprocket chain whip tool.
The process of removing a typical cassette lockring and cassette stack removal is outlined in the short clip below.
Using FR-5G or FR-5GT with Guide Pin
The FR-5G and FR-5GT include a guide pin for greater stability during the removal and installation process. Remove the skewer or thru axle and install the FR-5G or FR-5GT. Make sure the teeth are fully engaged in the lockring. Hold cogs as described above and turn the tool counter-clockwise.
Cassette Cog Lockring Installation
Cassette freehub bodies and cassettes are often designed so the cogs will fit in only one orientation. This permits manufacturer to align “shifting ramps” to specification.
- Inspect splines of freehub body. Look for a wide space between splines. Inspect the internal splines of cogs. Look for a wide spline to mate with wide space in freehub body. Align splines and engage all cogs.
- Install spacers in same orientation as when removed.
- Grease threads of lockring and thread lockring into freehub.
- Install cassette lockring tool and install quick release skewer. Thread skewer nut on outside of lockring tool.
- Snug skewer nut against remover. Skewer acts as a holding device for freewheel tool.
- Turn remover clockwise until lockring is tight, at least 360 inch-pounds (approximately 40 Nm). For installing lockring, use of the sprocket chain whip tool is not required.
FR-5G speeds installation as well. Simply insert the FR-5G into the lockring splines and tighten fully.
Threaded Freewheel Removal
This type of freewheel requires the FR-1.2
These types of cog systems will have either recessed notches or splines that sit inside and lower than the smallest cog. Older Suntour freewheels had two recessed notches. Some Suntour freewheels come with four recessed notches. Shimano freewheels and Sachs freewheels have a series of small square shaped splines. Atom and Regina freewheel use a series of star shaped splines. Park Tool makes freewheel removes for all these types of freewheels. NOTE: Falcon freewheels have a larger spline than Shimano. Use only the FR-7. DO NOT use the FR-1.2 on Falcon freewheels.
- Mount bike in repair stand and remove rear wheel from bike.
- Remove quick release skewer.
- Inspect freewheel center and select correct type of remover.
- Engage remover into splines/notches.
- Reinstall quick release skewer with skewer nut on outside of remover. If solid axle-type, use axle nut to hold frewheel tool.
- Snug skewer nut against remover. Skewer acts as a holding device for remover.
- Turn remover counter-clockwise using a large adjustable wrench. Park Tool removers will also fit the hex end of the Park Tool sprocket chain whip tool SR-1, or the Park Tool freewheel wrench FRW-1. It will typically require some force to turn the freewheel. Another option is to mount remover flats in hard jaws of vise, and turn rim counter-clockwise.
- Turn remover only 1 full revolution counter-clockwise. Loosen and remove skewer before continuing to remove freewheel.
- Continue to turn remover counter-clockwise until freewheel is unthreaded from hub. Lift freewheel from hub.
Threaded Freewheel Installation
- Lubricate heavily with grease or anti-seize inside mounting threads of freewheel.
- Lay wheel on bench, and hold flat. Hold freewheel so cogs are parallel to wheel rim and lower freewheel onto threads.
- Sight right side of hub and freewheel. Axle should appear centered in hole of freewheel. If axle appears off center, freewheel may be cross-threaded on hub threads. Remove and realign.
- Begin threading cogs clockwise by hand until freewheel feels fully threaded. If a great deal of resistance is encountered, remove and attempt better thread alignment.
- Use sprocket chain whip tool to rotate cogs clockwise. This will fully seat freewheel against hub.
- If a new freewheel was installed or in new wheel installed, check all adjustments of the rear derailleur. See Rear Derailleur Adjustments.
There are some brands and models of thread-on freewheels that have use a lockring to hold the cogs to the freewheel body. This lockring can sometimes be removed, however, there is typically no need to do so. Individual cogs of these freewheels are not typically available. The lockring is used to assemble the freewheel unit, and it is not intended for service. When the cogs wear out, the entire freewheel as a unit must be replaced. In the freewheels below, notice the cog lockrings. These are not “cassette” systems, but threaded freewheels and use the FR-2 and FR-1.2 respectively.
Older Cassette Hubs (non-lockring ring type freehubs)
Older freehubs may lack notches or splines adjacent to axle. These older freehub cogs did not use a freewheel or cassette lockring removal tool. There will be a dust cap for the hub on the right side, but no recessed notches or lockring splines at all. The first cog acts as a lockring for the other cogs.
- Use two sprocket chain whip tool.
- Place first sprocket on second or third cog, holding it clockwise.
- Place second sprocket tool on first cog to rotate it counter-clockwise.
- Arrange sprocket tools so they form a “V”. This gives you better mechanical advantage. See image above.
- Rotate first cog counter-clockwise while holding second sprocket chain whip tool. This loosens first cog. Remove cog and pull off other cogs.
Installing Older Non-Lockring Freehub Cogs
- Grease threads of smallest cog.
- Install cogs and spacers on freehub.
- Thread on smallest cog and secure clockwise with sprocket chain whip tool.
2Freewheel Tool Compatibility
3Cassette Cog Lockring Removal
4Using FR-5G or FR-5GT with Guide Pin
5Cassette Cog Lockring Installation
6Threaded Freewheel Removal
7Threaded Freewheel Installation
8Older Cassette Hubs (non-lockring ring type freehubs)
9Installing Older Non-Lockring Freehub Cogs