One day while riding home from work I started experiencing “chain suck” of the worst kind. When I coasted my chain wrapped around the freewheel and I had no choice but to keep pedaling. I knew what was wrong. The freewheel no longer turned.
It was worse than riding in a fixed gear because not only could I not coast, I had to keep turning the pedals or the chain would jam up on the chainwheel as well. I made it home without stopping.
I decided to disassemble the freewheel and see what caused the failure. It had been knocking ever since I installed it, so I figured it would fail eventually.
Disassembling a freewheel is not recommended. It’s not worth the hassle. In my case, I wasn’t trying to make a repair. I was just curious. This was an old 6-speed freewheel that nobody uses anymore. The main benefit of newer freewheels is that the axle has more hub support, so is less likely to fail. That has never been much of a problem for me so I’ll keep using the old-fashioned 6-speed until it’s no longer available. That might be in my lifetime.
The key to disassembly is having the right tools and knowing that the lock ring with the two recessed holes (that might take some kind of tool) is a left-hand thread. The late Sheldon Brown wrote about freewheel disassembly.
Using a punch and hammer, I tapped off the lock ring and looked inside. I saw about 100 1/8-inch bearings, minus cages. Sure enough, a ball bearing on the upper race disintegrated and over time the pieces migrated, causing a jam-up.
So much for my $25 freewheel. Cogs wear out on freewheels, which is the main reason they get tossed. What’s especially frustrating is when you have a new chain and a old freewheel or an old chain and a new freewheel. The chain skips on the freewheel and makes life miserable. You know it’s time for new cogs, a new chain, or both.
Sometimes you can get away with changing only a cog or two. Typically, the smaller cogs wear out first, although if you ride around in the same cog all the time, that’s the one that will wear out.