Hi guerney, its not a electric bike its electric moped, look at my profile picture, you try humping that up 2 flight stairs. mind you I guess my brother would help me up stairs. Its just that Ive had moped in my flat for 3 months, fixed it, then back up to flat again waited another month for parts. back on road again. 2 days later dam tyre goes flat. its just disheartning having to go all through that again. But I guess you are right, I will see what happens in the morning when I check tyre again. I just pray it is the valve. But if not will ask brother to give me a hand up stairs again