Amey,
Boy, you surely are having some major problems. Was your colectomy done for Colonic Inertia? Also, how long ago was your surgery (forgive me if you've posted it and I didn't see it).
I can't even imagine not urinating AT ALL!! That cannot be healthy!! Especially since you bike 20 miles a day, you must be, or at least should be, losing a lot of fluids. So, there isn't anything other than the Sorbital that can help you in obtaining a bowel movement?
I'm guessing that when my surgeon mentioned removing what very little colon I had left as a last resort - that may mean resorting to a bag - he didn't come right out and say that - this is my assumtion.
Boy, there is so much I do not know, but I'm assuming that they would somehow close up your rectum and disconnect the small intestine from it and change the colectomy to a colostomy.
At this point in the game I'm not ready for that and I will continue to find ways until there are no more before I would even consider the bag. But then again, if I were in your shoes and living the quality of life you're living - my opinion might be different.
Whatever you decide to do and the direction you wish to take, may it give you a better quality of life than what you're living now. I would like to keep updated on what you find out in your search for answeres. My e-mail is availiable in my profile if you would like to keep in touch.