Originally Posted by
bikeaddiction1
Most mountain bike shorts, whether the have their own padded liner, or if you wear them over a liner or road shorts, are abrasion resistant, where road spandex will easily snag on racks and branches.
I'll second that. You can definitely wear bib type shorts but if they are expensive you may want to protect the thin spandex they are usually made of.
Sort of depends on how long you are riding too. If it's short duration you don't really need padding but it's nice if you put in a lot of time, just like a road bike.
Another thing to consider is choosing a well fitted pair of shorts/bibs. You tend to come off the seat and position behind the saddle more often during a ride and a loose crotch can snag annoyingly on the saddle.