Kev, that was awesome.
On the original topic... there is some consensus that the magic gearing is 69". I agree with this. 46 or 47 x 18 have been my favorites. I just picked up a better wheel (suzue promax, had been using a suzue basic) and it came with a 17 t. I feel like I'm mashing now, compared to the 18 t.
YMMV!