jim10040

Right after I cleaned and lubed the chain (TONS of gunk!), I Was Just Riding Along and the chain is skipping like crazy. Like 2-3 jumps per crank. The chain measures right at 12" (not an extra 1/8" or whatever the tape measure rule is that says your chain is worn out), but (and this is a big but), the chain is way forward of the teeth on the cogset. That is, when I put a bit of pressure on the crank, I can see a big space between the chain rivets and the teeth behind. Maybe the cogset needs replacing but the chain doesn't? What do I need to check next?

operator

Sounds like the chain is worn like hell. How much have you ridden on this.

jim10040

I've only had the bike 4-5 years, I only ride a couple times a week. I really wonder about the chain-length question cuz I measure nearly exactly 12" from one rivet to a rivet about 12" away...didn't count HOW MANY rivets, but the chain doesn't act worn...doesn't flex sideways too much. But Then...this is the first time I ever tried to clean/lube the chain (or done any drivetrain maintenance) and I have no idea what I'm doing besides what the package on the Pedro's Chain Scrubber says.

matimeo

Your freewheel or cassette is probably worn out. Lots of times if you put a new chain on an old cassette it will skip because the cassette is worn and doesn't line up with the chain. Assuming you didn't just replace the chain but just lubed it, maybe somehow that made it ride funny on a worn cassette. I doubt your chain hasn't stretched any in 4-5 years so something is up.

Sprint75

Sometimes the gunk is all that's holding it together. When the grime and grit is cleaned out the tolerances are shot. You will probably need a new chain and a new freewheel or cassette. I've seen the same thing with an old bike that looked like the chain was fine, measured up just right. But, after it was cleaned it skipped like a pig. A new chain skipped badly too, so the whole drive train had to be changed.

due ruote 

If you removed the chain to clean it, check the link that you broke. Sometimes when you reconnect the chain that link will be "frozen". That's why chain tools have the second slot - this allows you to push the rivet slightly without the back plate being held in place, and loosens the joint just enough to function properly.

cudak888 

^
This wouldn't be it - the OP complains of constant chain skipping.

With a stiff link from re-insertion, there would be, at maximum, one skip during the chain's cycle.

-Kurt