Why's my freewheel wobbling?

swee'pea99

Legendary Member
My daughter's bike is not playing nice - the chain's juddering/jumping. The reason is obvious from this:


View: https://youtu.be/8xz72lVRCSs


Does anyone know why the thing has that wobble to it, and what I might do to try & fix it? (It's an ancient French block, if that's at all helpful.)
 

TheDoctor

Europe Endless
Moderator
Location
Stevenage
Axle is bent would be my guess.
 

Cycleops

Guru
Location
Accra, Ghana
I would say the hub itself is bent as its the freewheel that's oscillating while the axle stays still. In inspection when off the bike should reveal the offending component.
 
OP
OP
swee'pea99

swee'pea99

Legendary Member
I would say the hub itself is bent as its the freewheel that's oscillating while the axle stays still. In inspection when off the bike should reveal the offending component.
That was my first instinct, but thinking about it after TheDoc posted, i guess if there was a kink in the axle, even a 'true' hub would follow that kink and wobble. (Have to say I'm struggling to think how an axle could get bent.)
 

Cycleops

Guru
Location
Accra, Ghana
Although it looks bad, does this cause the chain jumping? I’ve bikes with similar movement but they’re ok.
Yes, I'd be surprised if this caused the chain to jump.
 

nickprior

Veteran
Location
Kelso, Borders
I had this happen once with a 105 freehub. On investigation it appeared the freehub bearings were completely mangled, and the chain was definitely jumping at random. New freehub, problem fixed. Never did diagnose the cause of the problem but I would probably point the finger of blame at the amateur mechanic who put it together in the first place. That would be me ...

I've also suffered with a bent axle which in the end fatigued the chain stay so much it snapped. This was a much abused hard tail mountain bike, and I have no idea how the axle got bent. It could have been during one of many impact rich outings.

How relevant this is to the OP's situation is entirely dubious but if it helps someone, well and good.
 
OP
OP
swee'pea99

swee'pea99

Legendary Member
Yes, I'd be surprised if this caused the chain to jump.
Absolutely! Indeed it doesn't just jump - the chain seems to get stuck between sprockets and, as it were, rides between them. So the chain is effectively sliding over the tops of the teeth and not engaging at all. Which is highly disconcerting, to say the least! I think I'm going to cut my losses and replace the wheel. It's probably 50+ years old, so I think you could say we got our money's worth. Thanks all.
 

Globalti

Legendary Member
It's nothing to do with bent axles or anything else bent; all of those old-school freewheels wobble like that. I've seen so many that I've even wondered if they were manufactured that way to help the chain derail because there aren't any ramps. Replacing it will only produce the same wobble.

The skipping chain may just be due to the fact that it's clogged with filth.
 

iluvmybike

Über Member
Cheap end freewheels always oscillate like that especially as they get older. There seems to be a lot of the gunge between the sprockets so if the rest of the drivetrain is as gungy then stuff is going to wear out & that will cause gear problems
 

tyred

Legendary Member
Location
Ireland
As mentioned, I'd consider that wobble normal for an older freewheel block. If you have a lot of patience you could strip it and play around with shims and improve it but it will make no functional difference so long as the bearing spins freely.

As for the skipping chain, it does not look worn enough in that video to slip. My guess is that you have a stiff link(s) in the chain. Inspect each link to see that they all move freely and flex any that seem stiff from side to side to help free them out. Also check that the rear mech is free moving with good spring action and capable of taking up the slack in the chain.

As for fitting wider gearing, you say French? Is it a French made bike? If so, the threads on the hub are probably the French metric standard thread pitch so good luck getting one of those. Wide range 4 speed blocks of any kind are pretty rare. Your rear mech may not cope with bigger sprockets. The spacing is probably narrower than what you'd require for 5 or 6 speeds.

If you do need lower gears, it's probably easier to fit a smaller chainset. Or my personal choice to shove a Sturmey Archer AW3 in it and have wided gear range and easier maintenance.
 
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