Descr1: 1. A person gets off the bicycle
  2. The person shoots the bicycle with a gravity gun causing the bike to fall down the stairs
  3. The person is teleported onto the bicycle
  4. The person and the bicycle slide downward on the stair railing
Descr2: 1. The player shoots an explosive behind a bike at the top of stairs
  2. The  bicycle slides down a hand-rail towards the player
  3. The player instantly mounts the bicycle that is sliding 
  4. The player slides down the hand-rail on the bicycle