We heard that in the swayamvara of Sita. The one who can lift the dhanush(Shiva's bow) will be termed as the worthiest to take the hand of sita. Although some says that Ravana also tried his luck and could only lift the bow a bit but finally gave up. Rama was the only one who lifted it. But I want to know a thing other than being a god himself id Rama have any speciality to lift the bow ....
I think the best Answer of your Question Should be NO
Without any specialty He was able to lift the shiva bow Cause He was incarnation of lord Vishnu and both of god Vishnu and Shiva are same It ain't true that only Rama Can Lift The Bow Of Shiva. In Mythology there is a story Of Sita In her childhood, Sita lifted the bow single handily and having seen that Janaka decided that he would give his daughter only to the man who could lift the bow.
Here is the source of Wikipedia
King Janaka of Mithila had a daughter named Sita. In earlier part of her life, Sita while playing with her sisters had unknowingly lifted the table over which the bow had been placed; which was something no one in the kingdom could do. This incident was however observed by Janaka and he decided to make this incident as the backdrop for Swayamvara.
Why Rama Lifted The Shiva Dhanush: