“Cycles", alternatively referred to as "Cycles Solo", is a song that was made playable in the Weird Autumn update. It's the song that plays while Mae rides Gregg's bike with him, and is made available to play after the third hangout with either Gregg or Bea. Listen here.
It's the only playable song featured in the game without any known lyrics whatsoever, and the second without lyrics shown during the song after "Space Dragon". This is likely due to the fact that it originated as part of the soundtrack before being made playable in the Weird Autumn update.