I used a whole lot of tricks to build the rings. Basically its a rock population. I couldn't get the shader for the rocks surface right. So I used the one that came in the NWDA planet pack. Here are some pictures of the node network including the clip file, so you don't need to reinvent everything. (1.4 million rocks....)
Render times vary a lot, 1 to 3 minutes per frame. Some take less time, some take a bit more, at 640x360.
Oh, and that bike? It's hard to spot, but its there
The original movie was 20fps, but that didn't work well, 24fps was no real improvement. 30fps, is great! I'll stick to that right now.