Question for any bike mechanics

Triathlon Forum
1

I have a question that I’m hoping someone can explain. For my daily commute to school I have a single gear bike that I ride. Recently it’s been insanely cold here (Detroit) and I’ve noticed something odd. Whenever the temperature is below 0F, the gear on my bike occasionally fails and leaves me pedaling without driving the wheel. This has only happened on days that it is extremely cold. One day last week I ended up having to walk the bike the last 1/4 of my trip because the gear just wouldn’t drive the wheel, but on the way home the temp had risen to about 10F and I had no trouble pedaling.

Does anyone have any clue why this might be happening? It’s driving me nuts.

2

Metal contracts when it is cold, my guess is that you have a gear that is a little close for comfort, meaning chain is just a little lose for the gearing. Do you have horizontal drops? If so, pull back the wheel to tighten the adjustment. I’d guess you have vertical, & you are rolling what you got for your gearing.

A chain tensioner would fix it.

I have a MTB with vertical that I can do without a chain tensioner, 42x18 I think. I drop a chain every now & then.

3

If your bike is not fixed gear, and you can coast, then you have pawls and teeth in a freewheel mechanism (depending on how your bike is set up, in your cassette hub or in your freewheeling single gear). In very cold temps, the grease hardens and prevents the pawls from engaging the hub. Result: you can pedal, but the bike goes nowhere.

Edit:
Solution for the extreme cold: use a solvent and remove all the grease. Replace grease with oil (and oil frequently during the winter; oil creeps out eventually, but the extreme cold slows this process, depending on the temps and on the viscosity of the oil). When the temps consistently climb back up, replace the grease, ride and maintain normally.

Greg @ dsw

4

Sounds like I have my answer. Anything I can do about this or should I just deal with it on the few days it gets that cold?

5

see my edit …

6

Thanks! This question has been on my mind every time I’ve ridden recently. Now I can stop worrying about this and pay more attention to dodging cars.

7

Glad to help.

You’re a stud in you ride in 0 deg.F temps, my limit seems to be about 20F !

8

I know canadian degrees are warmer than american degrees. eg. 32 here is 0 up there. Maybe there’s another nationality of degrees he’s referring to.

I have absolutely no idea if my bike works below 40.

9

If your bike is not fixed gear, and you can coast, then you have pawls and teeth in a freewheel mechanism (depending on how your bike is set up, in your cassette hub or in your freewheeling single gear). In very cold temps, the grease hardens and prevents the pawls from engaging the hub. Result: you can pedal, but the bike goes nowhere.

Edit:
Solution for the extreme cold: use a solvent and remove all the grease. Replace grease with oil (and oil frequently during the winter; oil creeps out eventually, but the extreme cold slows this process, depending on the temps and on the viscosity of the oil). When the temps consistently climb back up, replace the grease, ride and maintain normally.

Greg @ dsw

^^^^This.

Also, if your rear wheel has a “flip-flop” hub, consider using the fixed gear during really cold days.

10

Or water got in the freewheel /cassette and freezes up. With temps you suggest it would probably happen warmer than your temps, so I side with the grease logic. I had that happen to me a couple times with the cross bike in cold weather, darn power washers.