This is totally strange. I use a pair of bibs that is the same manufacturer and model of regular cycling shorts. They are pretty nice--maybe not top of the line but definitely on the upper end scale.

When I wear the bibs I have some severe pain in or near the sit bone on one side. I thought it was a saddle issue so I replace the saddle. The pain persisted. I started wearing my regular bib shorts and the pain stopped.

The cut of the shorts is the same. The padding and design is the same in both shorts except the pair of shorts I'm having problems with are bibs......

The only thing I can think of is the tire around my waist has gotten so large the bibs are pushed to their max and are pulling up towards my shoulders more than normal. I was enjoying wearing the bibs as they seemed to hold the tire in and not make is so visible.....Seems like I'm always considering lipsuction this time of year.