from Rookie’s keyboard
Hello, friends
It’s a hot sunny Saturday afternoon where I live – an ideal time to write a post on a popular issue, namely – “ghost pedaling”.
Don’t worry. This is a metaphor. We won’t be calling ghosts to steal your bike.
Joking aside, ghost pedaling is essentially rotations of the cranks and respectively the pedals when walking the bike.
This is normal for fixed-gear (track) bikes, but the vast majority of bicycles have a cassette freehub or a freewheel that allows the rear wheel to spin independently of the pedals.
The most likely sources of the problem are:
- Damaged freehub
- Dirt freehub
- Super tight locknuts of the rear hub
- Ultra-tight chain
Understanding Rear Hubs
You have to know how a freehub works to understand the problem.
The graph above shows the basic anatomy of a rear hub.
The enclosure of the hub is known as a hub shell.
The hub shell rotates around the axle and contains the bearings of the hub and the ratchet ring.
The next photo presents the freehub body – the part allowing the bicycle to coast when the rider is not pedaling.
When the freehub body is spinning clockwise(pedaling), the pawls open and grab the ratchet ring.
The “hug” between the pawls and the ratcheting ring connects the freehub body and the cassette, to the hub shell and makes it possible to transfer power to the rear wheel.
When coasting(or backpedaling), the connection between the freehub body and the shell is broken.
The hub shell continues spinning, but the freehub body remains stationary and so do the chain and the pedals.
The illustration above shows what happens during pedaling – the freehub body is spinning anti-clockwise (backward pedaling) whereas the hub shell and consequently the wheel remain stationary.
When coasting, the freehub body, the cassette, and the chain remain motionless while the ratchet ring keeps spinning and“brushing” the pawls of the freehub body.
The sliding of the ratchet against the pawls is the source of the clicking sound that you hear when coasting.
When you are pushing the bike, the hub goes into“coast mode” since there is no external force spinning the pedals.
Sources of Ghost Pedaling
- Seized or Damaged Pawls
One of the ways to know with greater certainty whether the pawls are malfunctioning is to lift the bicycle upside down or clamp it on a bike stand and then spin the pedals backward.
If the rear wheel is spinning along with the pedals, then there’s a very high chance that the pawls are either too dirty or broken.
- Dirty Pawls
The grease lubricating the pawls will eventually mix with dirt and harden.
The contamination makes the pawls less responsive, and they may seize against the ratchet ring.
One solution is to spray a degreaser into the opening of the hub while spinning the freehub body to spread the substance over every pawl.
Then you can re-lubricate the hub with oil to keep the mechanism running smoothly. Stay away from thick oils as they may prevent the pawls from moving freely.
If you don’t want to bother with two different chemicals, you could consider using a product that does both.
One option is Boeshield T-9 Bicycle Lubricant which cleans and lubricates bike components.
А Cassette Hub
If you have a freewheel, you can use the same method.
The only difference is that you will have to clean the freewheel itself rather than the hub.
If you have a freewheel, you will have to spray this area.
In severe cases, you may have to disassemble the hub to fully service it.
But the freehub bodies of cheaper hubs are not meant to be serviced, and there’s no way to open them without “excessive force”.
In that case, you will have to buy a new freehub body.
If you have a higher-end freehub, there’s a greater chance that its freehub body is serviceable.
- Broken Pawls
If a pawl is broken, a small piece may get stuck in the hub and cause unwanted binding against the ratcheting ring.
The result will be occasional ghost pedaling when pushing the bike.
To fix this issue, you will have to replace the broken pawls, the freehub body, or the entire hub.
- Tight Cones/Locknuts
Super tight locknuts of the rear hub could be another source of ghost-pedaling.
The cone nuts on a hub are a bit tricky to set.
If they’re too loose, there will be play in the hub; if they’re too tight, the wheel won’t spin freely. Both situations are not ideal.
A tight cone nut could be preventing the freehub from operating independently by pulling the driver body into the hub shell.
In consequence, the freehub fails to disengage and keeps rotating. The chain and the pedals have no choice but to spin too.
If this is the source of the problem, readjustment of the cone nuts will be necessary.
If you have a Shimano freehub, only the cone on the non-drive side of the hub is designed for adjustment.
Shimano is among the few manufacturers sticking to a cup and cone system due to its simplicity and the ability to service it more easily.
Other producers use cartridge bearings for their hubs. If you have a similar hub, you won’t have to deal with a cone but with an end cap. If the end cap is too tight, it will create a similar effect and prevent your bicycle from coasting.
Hence why manufacturers install a special mechanism meant to keep the end cap where it’s supposed to be.
One example of such implementation would be SRAM S30 AL gold/RACE/SPRINT & S27 AL COMP hubs. Those models have a set screw for the end cap. If the screw is set improperly, or the mechanism underneath is malfunctioning, the coasting of the bike will suffer.
- Tight Chain
During coasting the freehub body and the cassette are resisting the ratchet ring which is spinning and brushing the pawls.
The contact between the ratchet ring and the pawls may cause small movement of the freehub body and consequently the cassette.
If the chain is too tight (not enough slack), the subtle movement of the cassette may be enough to spin the chain a bit and with it the pedals.
- New Hub
If the hub is new, the grease in it may still be too thick. On rare occasions, this may be enough to stop the pawls from disengaging as quickly as possible.
Sometimes this is the case even for expensive hubs. I’ve heard of people experiencing ghost pedaling with Chris King hubs for a bit due to fresh lubrication. Time and riding fixes this problem.
- An External Object
If there’s an external object stuck between the largest cog of the cassette and the spokes, the bicycle will not be able to coast effectively.
A piece from a rag used to clean the cassette is one example. Even a small stray from it could be enough.
- An Improperly Assembled Hub
The rear hub contains many pieces that come in a specific order. If the hub hasn’t been assembled properly after servicing, one or more parts may be causing extra friction preventing the freehub body from operating as planned.
You Have a Flip Flop Hub
If your bicycle has a flip-flop hub (one side is a freewheel, the other a fixed cog), check if you’re actually using the freewheel.
The bike shop or the previous owner may have put the wheel in “fixie” mode.
And there you have it, friends. Ghost pedaling demystified.
Until next time,
– Rookie
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