Why do I locked my bike?
The answer is Believe in Allah azzawajall a.k.a iman
I place my trust in Allah, thus I locked my bike and then left it with the hope the bike would be there when I came back inshaAllah-with Allah's will
I locked my bike because Rasulullah salallahu alayhi wa salam once told someone that "Tie Your camel, and then put your trust in Allah", thus I locked my bike as an effort from my part in making sure that the bike would not get stolen before asking for Allah's protection
p/s: a camel would surely wander around if it's not tied for it has the ability to walk or move. What about a bike? as far as I know, no bike would automatically move independently without an operator. Why it is very hard to trust people nowadays? Why do people steal? Thieves do not have taqwa-fear of Allah =(