In legends of Sant Changdeva and Sant Gyandev they are said to have travelled on bricks and tigers. Can anyone elaborate more than what is on wikipedia? Were they riddhis, siddhis? What was specific significance of brick. It can't be mere co-incidence since that doesn't happen in life of such spiritually advanced yogis.
Traveling on tigers basically refers to the fact that a wild animal like tiger has been tamed by the saint. Then, this is not uncommon for highly adept Yogis. Loknath Brahmachari also displayed this Siddhi.
Ahimsha is one of the eight limbs of Yoga as known from various scriptures. And, a Yogi who has really established in himself, Ahimsha, is not harmed by even those animals, which are by nature ferocious and likely to cause harm.
This is mentioned in Patanjali Yoga Sutras' 2nd Chapter (Sadhana Pada):
ahimsapratishthayam tatsannidhau vairatyagah ||
Non-killing being established, in his presence all emnities cease (in others). 35
Swami Vivekananda's commentary on this sutra is as follows:
If a man gets the idea of non-injuring others, before him even animals which are by their nature ferocious will become peaceful. The tiger and the lamb will play together before that Yogi and will not hurt each other. When you have come to that state, then alone you will understand that you have become firmly established in non-injuring.
So, this particular Siddhi of Yoga is achieved by truly mastering the Ahmisha limb of Yoga.
For the time being, it's a partial answer. If "traveling on bricks" means traveling in air then that's a Yogic Siddhi and I will update my answer later.
I think that while they surely had siddhis one should bear in mind that tiger is usually used as symbol of power of Vedic knowledge (hence simhasan of kings, and also narasimha avatar). Brick wall could be related to use of brick for yagyas and/or the concept of keeping Hari on brick which is why he's known as Vitthal. Feedback, brainstorming welcome.