After reading all of your input on my last thread, I decided that I was justified in thinking it's ridiculous for a shop to damage a fork while attempting to install a crown race, and I went back to see what they would say. To my surprise, they were extremely apologetic. In exchange for their error, they gave me a bottom bracket (which I needed) and installed it for me. I also needed some singlespeed chainring bolts, so I paid for those and the mechanic installed them as well. With that settled, I went home and worked on finishing the build.
I finally got everything together and set up tonight, and (of course) I was very excited for the inaugural cruise. The good news: The bike is a lot of fun. It's a fixed gear 29er with a disc brake up front and low gearing, and it's just awesome to fly around town on it. I rode around some back streets, rode over some little curbs, and did some trackstands (easy as can be with the upright geometry and short gearing). The roads in my town are pretty clean, so I was surprised to hear the occasional "ping!" of a rock off the downtube, and some occasional little cracks suggested that my eccentric bottom bracket wasn't tight enough, so I headed for home. Trackstanding at a light behind a car, I lost my balance and went to put a foot down. As I did, I heard a "pop!" and the sound of something small and metallic rolling away. I walked to the sidewalk and scoured the street, and found, to my amazement, one half of a chainring bolt. I looked down to find that this was the third to fall off, and the other two were extremely loose. The threads were dry - no Loctite, not even any grease. I was literally riding for fifteen minutes max. I'd heard some similar noises up the hill to the light, and the first two probably fell off then.
I really can't believe this happened. I was pleasantly surprised with how agreeable the shop was about comping the bottom bracket and the half hour of labor, but I am shocked they were so sloppy. Again (in hindsight, I should have seen this coming). And this time, it was a very dangerous mistake. I've never had a chainring fall off of a fixed gear at speed, but I can't imagine it's pretty. I know I should be more aware of these things while I'm riding (and probably shouldn't do shakedown rides in the dark), but this makes the first mistake look trivial.
That's it. From now on, it's either do it myself or do it at the one shop I have real ties to (and I know and trust every mechanic there. They're much better wrenches than I am, and I know because they're the people I learned from). Ugh.