Gotta have a seat with a groove, a hole, or both. Every mountain bike seat I have seen has a groove in it, at a minimum, where road bike seats seem to be more like thin hard plastic with no groove. In addition, road bikers lean forward so much, there is more pressure on that region.
Mountain bikers move around on the seat a lot more, and stand up while doing any descending. You have to get off the seat and get your rear end farther back than the seat s0 you don't go over the handle bars on larger drop offs.
I'm taking every precaution in case I become LC's full time photographer.http://www.bicycleseats.org/extra-deep-relief-zone.htm