So I just finished taking the SRAM PG950 cassette off my bike for the first time. As I went to lay it on the bench, I was surprised that it didn't stay in one piece. Instead, the small bolt that runs through all the big cogs fell out and all 9 gears slid past each other in a small jumble on the bench.

I'm talking here about the little bolt that's about 2mm in diameter, maybe 25mm long, and passes through the purpose-made holes in the gears and spacers. As it turns out, this bolt--whose job, it appears, is to hold the cluster together--was not actually screwed into anything. And as far as I can tell, there is nothing in the assembly that's threaded so that the bolt couldscrew into it. As it is, the bolt just passes through 6 cogs and 6 spacers, and the threaded end is just sitting there. In its current state, it's just a relatively unnecessary, and loose, guidepin.

So, I reassembled it the way it was, figuring that if it hadn't hurt anything after 1700 miles it wasn't going to start now. But what's the story here? What should that little bolt thread into? And should I just remove it and be done with it?