from Rookie’s keyboard,
Hello, friends
What’s up? A new day, a new post.
It’s still early where I am, but I love getting some writing done before 10 a.m.
Today, I decided to cover a topic inspired by what I call the Cyclist’s OCD.
I was in the midst of of indexing the gears of an old-school MTB at the shop that we use for commuting to the local food station when a colleague noticed that the freewheel was moving up and down a.k.a. wobbling.
Honestly, that’s normal.
The 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.
- Imperfect 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 issue.
The only solution would be to upgrade to a higher-end hub or switch to a cassette freehub.
Who Cares?
That up-and-down movement isn’t a big deal and does not cause a perceivable degradation of performance.
In most cases, the bike remains stable and shifts just fine. Truth be told, one would be hard-pressed to find a freewheel that doesn’t display at least a minimal amount of imperfection.
After all, freewheels are reserved for cheaper bicycles and thus the manufacturers have no incentive to produce hub shells with no deviations.
Having said that, it’s necessary to rule out major failure points before concluding that the freewheel is “healthy”.
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.
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.
- 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. 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
Untightened freewheel?
If the freewheel isn’t fully tightened to the hub, it may move around.
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.
Until next time,
Rookie
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