Thanks for the thoughts. The belt is a double sided object with thickness, but I found that it had split vertices around one edge; I've welded those, and subdivided it a couple of times to smooth the sharp edges. I did try the additional collision options, but maybe in conjunction with the smoother belt and increasing the steps it might work better. I'll give this a try later on. Another thought that occurred was to do it in stages - export the partially cinched tabard, and run another simulation on that starting with a smaller belt.