How long will a 100 mile bike ride take?

Excuse me, I'm curious about the duration of a 100-mile bike ride. Could you please elaborate on what factors might affect the time it takes to complete such a distance? For instance, would the terrain, the cyclist's fitness level, and the weather conditions all play a role in determining the overall time? Additionally, could you provide a rough estimate of how long the average cyclist might expect to take to finish a 100-mile bike ride? I'm trying to plan for an upcoming event and would appreciate any insights you could offer.