53-21 or so. Not sure on the 21, it was the third largest of an 8-speed Campy cassette. I'm sure I mashed some to get going, but I probably did when it was geared, too -- though I can't really say to what extent.

The more I think about it, though, the more I wonder if the wheel didn't slip to cause the derailer self-destruction (even though I was in low gear, I was mashing to get started up a hill from a dead stop). If it matters, the drop-outs are forged Campy, with Campy skewers.

I think tonight I'll go home and do the following test: Stand on my bike with the brakes locked and mash the bejeezus out of the pedals to see if I can get the wheel to slip. I'll report back. Or not.