So your out on a ride, then all of a sudden your chain is skipping on the gears. Upon closer inspection you discover you have lost your top deraileur pulley . . . Now What? We went back a bit to look around, but the pulley and bolt . . . Bolted. So we found the next closest thing, a rusty nail. A few more miles down the road I wore through that nail and I once against force to scan the road for some piece of steal. I found a flat thin piece of steel and threaded through where the oulley bolt would have been, and Viola! I made it another 3 miles.
Lucky for me I have a collection of crashed out deraileurs so I had some pulleys hanging around. Who loses a deraileur pulley? Sure I admit I had it apart . . . 4 years ago! I have to admit it's not the first time this happened, last time I was able to find the pulley and found a nail to replace the bolt. Also I've been out twice with people and this happened, and funny enough we found nails to remedy the problem . . . sure are a lot of nails around where I need them.