Description of the Problem. During coasting, the freewheel is moving around/wobbling. The motion is perceivable only from the side.
Source of The Problem
In the vast majority of cases, the freewheel wobblе is caused by imperfections within the freehub body/shell.
Since the freewheel threads onto the rear hub, it’s affected by the deviations.
The most common hub shell deviations are:
- Off-center Sides
In the ideal scenario, the hub shell will be straight. However, this rarely happens in practice, especially when the hub is cheap.
It’s not uncommon for one side of the hub to be higher than the other. The unevenness causes the freewheel to move up and down.
- Sideways Threading
If the thread on the hub is at an angle, the freewheel will be tilted and not perfectly parallel to the flanges (ends) of the hub. The result is a wobbling freewheel.
When the source of the problem is a hub shell misalignment, the user can’t do anything to fix the problem. The only solution would be to upgrade to a higher-end hub or switch to a cassette freehub.
FAQ: Is a wobbling freewheel a source of concern?
Not really. Truth be told, one would be hard-pressed to find a freewheel that doesn’t display at least a minimal amount of wobble.
The main reason for that is that freewheels are reserved for cheaper bicycles and thus the manufacturers have no incentive to produce hub shells with no deviations.
The second reason is that a wobbling wheel does not cause a perceivable degradation of performance. In most cases, the bike remains stable and shifts just fine.
Having said that, it’s necessary to rule out major failure points before concluding that the freewheel wobble is standard and harmless.
Those problems would be:
- A Cross-threaded Freewheel
If the freewheel has been cross-threaded during installation, it will be offset and thus wobble.
The only solution, in this case, is to replace the hub and the freewheel (if its threads are damaged too).
It’s not possible to repair the threads on the hub because one cannot add material. And if you don’t add material, the diameter of the thread will be too small for the freewheel.
Unfortunately, it’s not easy to replace the hub. The process requires re-lacing of the wheel and spokes of a different length due to the new hub’s dimensions.
Note: There’s also a possibility that a part of the hub’s thread is completely missing. This may happen if the freewheel has been cross-threaded and later installed correctly. In that case, the hub should be replaced.
- A Bent or а Broken Axle or Hub
If the axle is bent or broken, the entire wheel could be wobbling because it’s rotating around an uneven surface. Technically, a bent axle would not cause the standard freewheel wobbling discussed here, but it could create the perception of such.
- Worn or Broken Bearings
If the bicycle is old, and the hub’s bearings haven’t been serviced, examining the hub for missing ball bearings or damaged cone or cup surfaces would be helpful.
In most cases, a rear hub with cup and cone bearings has nine 1/4 inch bearings on both sides.
- Loose Axles
If the hub has a lot of play in it, the wheel will be unstable and wobbling. If the hub uses cup and cone bearings, chances are that the cone adjustment is too loоse. In that case, the hub will have to be disassembled and serviced.
There are three degrees of cup and cone bearing service:
Degree 1. Degreasing and re-greasing of the bearings (routine maintenance)
Degree 2. Ball-bearing replacement, re-greasing
Degree 3: Ball-bearing and cone replacement, re-greasing
FAQ: Can an insufficiently tightened freewheel be the cause of the wobbling?
Technically, yes. If the freewheel isn’t fully tightened to the hub, it may wobble.
In practice, however, this is rarely the case because riding the bike tightens the freewheel onto the hub to an unbelievable degree.
Sometimes it’s necessary to use a cheater bar (a pipe slid onto the wrench) for extra leverage to remove the freewheel. Hence why it’s close to impossible to have a non-tightened freewheel on a bike that’s been ridden for a while.
If the freewheel is not tight on the hub shell, the cause is probably stripped threading rather than insufficient tightening.
Summary: What You Need To Know
- More often than not, a wobbling freewheel is the result of a misaligned hub shell or uneven hub shell treading.
- A freewheel wobble is present even on relatively expensive bicycles. One would be hard-pressed to find a freewheel with zero wobble.
3. In most cases, the wobble has no negative effect on the bike’s performance.
4. Unless the wobble is the result of major damage (e.g., broken axle, destroyed hub bearings…etc.), it’s not a source of concern.
5. If you’re unsure about the integrity of the hub, it’s recommended to examine and service it. If the bike is new, however, more than likely, the wobble is the result of a hub shell deviation.