If you really insist on trying this theory out, you need to look for a used Salsa Fargo. That is the only mountain capable bike that I know specifically designed for drop bars. Some folks have set them up with flat bars because they wanted super short reach setups. My experience with the bikeis, if you shorten the cockpit that much you will find climbing hills nearly impossible because you won't be able to keep the front end down. Then you will come to your senses and put the drop bars back on it that it was designed for.
