My relatively new freewheel is skipping intermittently in extreme cold temperatures (-40C). If I pedal backwards slightly then pedal forwards the freewheel will rotate forwards without rotating the wheel. Other times when I do this the wheel will rotate. The chain doesn’t seem to be skipping off the teeth at all either. You can hear what I assume is the internal ratcheting system clicking when this happens. Do you think this is just due to the temperature, the ratcheting mechanism is freezing up, or have I broken something? Any suggestions would be appreciated.
Freewheel skipping in extreme cold (-40C)
byu/deanc474 inbikewrench
by deanc474
5 Comments
Why are you out in -40° weather to begin with? You in Alaska or Canada? Or Russia? I’m going to guess the Grease solidified.
If this is only in extreme cold it is almost certain that the grease/oil in the ratchet/freewheel mechanism is too thick for the springs to rebound the pawls to engage the drive ring. Combination of the viscosity of the grease increasing as it gets colder and possibly the springs loosing some of their force as they get colder and their ‘elastic deformation’ declines.
This is likely a temporary issue but you could ‘flush’ the mechanism with a thinner oil once it has warmed up. This would likely require more frequent re-lubrication however as the oil isn’t going to be as durable as the grease from the factory.
ETA: [explanation](https://www.sheldonbrown.com/freewheels.html) and disassembled freewheels for reference.
Happens with the grease in Dura Ace and XTR at higher temps. I’ve heard of people pissing on the sprockets so they could continue their ride. I suppose at -40 you’d want to be quick so not to get frost bitten.
https://m.youtube.com/watch?v=PLMrHRuhxO4
I’d strip all the grease out and add a lightweight oil to the pawls and springs to see if that’s it.
Be careful, it’s easy to break the ratchet mechanism this way. The advice I was given for my free hub is to flush the existing oil using degreaser, and then use a light oil, like Dumonde’s Freehub Oil. That worked for my road bike through a few Edmonton winters. I destroyed a freehub before I discovered this though.