Is pipe in front of "townhome" private property? (state of Colorado)?

I live in a building that’s called an apartment but is actually what seems to me to be three “townhomes” attached to each other. I live in the first one, apartment “A”. About three feet to the side of each front door is a u shaped pipe that goes into the ground – not sure what it’s for. Running along the front doors/pipes is a driveway that goes to the back of the building, where the dumpsters, other apartments and a bike rack are located. I need a place to park my bike. I can’t do it to the pipe in front of my apartment’s door because my roommate already uses it (for 2 bikes). I’m not strong enough to bring my bike inside up three flights of stairs inside. I have been locking my bike to apartment “B”’s pipe because I just moved in and never saw a bike there. “B”’s residents want me to park my bike at the bike rack at the back because they want to use the pipe for their bikes. Due to a myriad of reasons, I’m not willing to park my bike at the bike rack unless the pipe is private property and actually belongs to them. Otherwise, in my opinion, it should be first come first serve. My question is, who is right? Is the pipe private property belonging to “Apartment B” or is it public property for all the residents of the building?