I can’t speak for what they looked like before the 1.23.0 update as it wasn’t something I had to mess with. On the current update I can confirm that I have a Game Sound slider and a 3d World slider on iPad. With the Game Sound slider set to “off” bike sounds went away. The 3d World volume slider appears to only control the nature sounds. This is with or without another program playing sound in the background.
Based upon the description of the two sliders I would expect 3d World to control bike sounds as well.