I know I saw it on this Forum.
Most likely in this Folder, although it could have been in the Classic and Vintage Folder.
I think it even won some kind of award for short film.
The woman starts off on the bike indoors, like some kind of photo shoot, because the bike is stationary, like it`s a prop.
But once she gets on and starts pedaling , it takes off and she starts getting younger, and begins to fly on the bike.