I started with 7/64 which I think is plenty strong (1,600 lbs), but decided to go with 1/8 (2,500 lbs) to give me a margin of error, and there's no appreciable weight/bulk difference between the two. 1/4 (8,600) would seem to be overkill, that's what I"m using for my bridge and it's noticeably bulkier than the 1/8.