Cool Saturday with gray clouds, light rain. Coffee, oatmeal and iTunes.  Out to the garage for some preventative maintenance on Thorpe.  The last two rides were very wet and he managed to pick up a lot of road grime.  Clean the rim walls, remove grit from the brake pads, general cleaning.  Check bolts and nuts.  Adjust brakes.  Check shifting.

It was during this last task that I discovered a nasty problem that could have led to catastrophe.  On the small cog I was getting some serious skipping.  Closer inspection revealed that the lock ring on the cassette had come loose.  The only thing holding the two small cogs and lock ring on the hub was the fact that it was in the dropouts.  Yikes.  How did that happen?

Then it dawned on me.  A few months ago during an errand trip I stopped at a grocery store to buy coffee and various sundries.  When packing the pannier I neglected to check all the straps.  On the ride back home one strap got caught between dropouts and the cassette.  It almost jammed my chain.  I’m wondering if that provided enough torque to loosen the lock ring.

That problem solved I finished up by cleaning and lubing the chain.  I’m experimenting with a wax based chain lube.  So far I’m happy.  I also checked the chain for wear using my Park chain gauge.  As Kent points out in this excellent post, measuring wear is the only optimum way to determine when to replace a chain.  Basing that decision on time (calendar) or distance ridden either wastes a perfectly good chain or allows the chain to wear to the point of damaging cogs and chainrings.

Now I’m ready for tomorrow morning.  Heading out at zero dark thirty (military phrase for really freaking early) to cheer for the crazies running the 3M Half Marathon.