There are plenty of questions you could explore to create a story inspired by the sight.
Who might the culprit be, and why did they leave it there? Could this be a statement about fossil fuels and our fragile grasp on life, or might a bunch of squirrels, badgers or buzzards have gotten up to no good in the gloaming? Is the Learner plate significant to the tale?
Why not make a play on the word ‘moped’, meaning small-engined two-wheeled vehicle, and ‘moped’, meaning behaviour revealing a melancholic mood?
Given the setting and the season, you also have the option to take a spookier route and write of ghouls taking nostalgic joyrides. I saw it at 7.15am and when I returned a few hours later, the bike had disappeared…
If you write or create something prompted by this, please send an email to judydarley (at) iCloud.com to let me know. With your permission, I may publish it on SkyLightRain.com.