Not a bad chain (or chain link) -- but it sure acts like it! How to spot a defective freehub.
A classic sign of a worn or stretched chain (and/or bent links) is one that "skips" or clicks loudly, especially during hard pedaling (such as going up an incline).
Because I have a heavy touring/commuting bike -- which also carries up to 50 lbs of additional weight on camping trips -- I am quite familiar with this problem. Due to this "heavy-duty" usage of my bicycle, I clean and lubricate my chain (and other drivetrain components) once a month and usually replace the chain every 1,200 miles.
Only a few weeks after a recent chain replacement, I noticed that the chain started "skipping" again -- or so I presumed because the symptoms felt/sounded identical to that encountered with a worn or damaged chain. I inspected the chain and sprockets for wear or damage -- none could be found. Ditto for the derailleurs. Odder still, I could not duplicate the symptoms while the bike was suspended on a bike stand, cranking the pedals by hand (and simulating road friction by applying light pressure on the rear brakes -- a rubber band on the brake handle can be used to do this).
On the road, the problem seemed to more likely to crop up when beginning to crank after coasting (freewheeling). I also noticed that the distance one to had to crank until the freehub ratchet "caught" was a bit longer than before. I removed the freehub from the hub and played with a little, turning the inner mechanism with my index finger. Bingo! Sometimes the ratchet didn't quite "lock" causing this hub to spin another one-eighth turn. It did this with mechanical roughness indicating worn internal components. Replacing the freehub (body) eliminated the problem.
The lesson here is that things are not always what they appear. If you pay close attention to the symptoms -- in this case: crank "free play" and when a skip most-often occurs -- troubleshooting is much simpler.
