Most snow bibs have a traditional front zipper for number one.
These days, most snow bibs are designed to be able to use the bathroom for number two without needing to take off the entire bib. This is achieved through a drop seat, which is a specialized zipper that allows the fabric on your backside to drop away from your body while the shoulder straps remain in place. It might take a few tries to master, but don’t let nature’s call scare you away from snow bibs.
Ski bibs are a great alternative to ski pants; (photo/Eric Phillips)