Q&A: Freewheel/cassette not working/frozen

Q: Hi Jim,
This happened over the weekend (it was cold): When I tried to ride my bike on Monday the freewheel would not engage with the wheel (it just spun). I moved the bike inside (it was stored in the garage) and adjusted the quick release, laid it flat on the floor and it worked again. I am not sure whether I fixed the problem or not. I have no confidence to ride it until I really understand the problem or issue(s) (it’s a 12-mile commute). Could you give me some tips?
Thanks,
Thomas

Q: Hi Thomas,
The freewheel (also called a cassette sometimes, though the two are different things) has little pawls and springs inside that work together to drive your bike. There's usually lubricant inside, too. My best guess is that the cold weather made the pawls stick and stop catching and driving your bike. When you brought your bike inside the heat warmed up the lubricant and the springs were then able to push the pawls back in place and drive your bike again. So, I think it'll work fine for your ride.

It won't hurt to add a little lubricant. To do this, lay your bike on its side with the freewheel facing up. Then turn the crank backwards and watch the freewheel move. You'll see that the part with the sprockets moves and the part it's turning on stays still because it's attached to the wheel. There is a small crack between these two parts of the freewheel and that's where you put the lube. A light spray lube like Triflow works fine. Or you can drip car motor oil on while turning the crank slowly to draw the lube into the crack and into the freewheel mechanism. You won't get all the oil in there but you just need to get some in there to refresh any lube that's in there and keep the freewheel working.

Note that if what you have is a cassette, it's harder to get lube inside it because there are pieces that block access to places to add lube. Click here to see a nice picture on Sheldon Brown's awesome bicycle website that shows the difference between freewheels and cassettes. Luckily, cassettes usually don't freeze or fail as often as freewheels and don't need relubing very often. If you want to relube your cassette you can remove the cogs (you'll need a cassette lockring tool and a chainwhip tool) to gain access to the body and drip some lube in. Or, if you want to do a professional job, consider purchasing Morningstar Tools' Freehub Buddy tools and lube that let you flush and fully relube it!
Jim