Today's mechanical adventure

On vacation, in a hotel room far from home. The Bike Friday came along in its suitcase. Nothing athletic on tap; it's just for leisurely exploring and local transportation.
The Friday does a "quick fold" in a minute or so, which is good enough for throwing it in the back of a small car or taking it on a bus or light rail.  But fitting it into its suitcase for airline transportation takes some disassembly. Front wheel comes off, drop handlebars are removed from the tall gooseneck stem and split in half, that stem is removed, as are pedals, etc. Packing it in the suitcase is tricky, a sort of three dimensional Tetris game with oddly shaped pieces. The packing takes me over half an hour, but unpacking and assembly is usually much faster.
Not today.
As I was all done assembling (so I thought) I lifted the rear wheel and pulled on the left shifter as I turned the cranks, to get the chain on the chainrings. But instead of the usual result, there was a big SNAP, I heard some little mechanical bit hit the wall, and there was a loud grinding, ratcheting sound from the gear train.
That sound was from the bottom of the Shimano 9 speed front derailleur cage dragging on the large chainring's teeth. The derailleur was in a weird position, I couldn't shift it, and I was afraid of mangling it if I turned the cranks.
The hotel is fitted with carpet specially designed to make tiny escaped mechanical parts* invisible. (*The technical name for such a part is a "pingfuckit.") I didn't know what I was looking for, but I spent at least ten minutes searching. The only thing I eventually found was a tiny flat washer, too small to fit a 5mm screw. I couldn't even be sure that was mine. Who knows how many devices had exploded in this room?
Working with a clumsy folding bike multitool, I unclamped the derailleur cable and took the derailleur off its braze-on mount. I could then see that the short inner link of the parallelogram linkage had lost its pivot, which seemed to have been a shoulder screw. More searching yielded only frustration. How could such a screw have totally disappeared? I tried substituting an ordinary metric screw, but it really needed a thicker bearing surface for proper pivoting. If I were home I'd have cobbled up some sort of sleeve for the screw, but here I have only what I brought with me.
It then occurred to me that it may have come loose during the flight. Digging around in the case, I eventually found the pivot screw. I was able to reassemble the tiny bits, remount the derailleur and see it shift all three chainrings.
AFAICT this failure had nothing at all to do with this being a folding bike or traveling by air. The pivot screw just decided to abandon ship at a weird time. I'm glad it happened at a place where I could (eventually) recover it, and not somewhere on the road.
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- Frank Krygowski