Spotting what is unmistakably a stolen bike, chained up in the street or listed for sale online, produces a strong urge to simply take it back. That instinct carries real legal risk for the original owner, and the reasons are not at all obvious until they are spelled out.
Don't take it back yourself, even if you're completely certain it's yours — call the police non-emergency line (0900-8844) with your original aangifte, the police report you filed when it was stolen, and the frame number, which should be on your purchase receipt or registration. Let them handle retrieving it, especially if it means confronting whoever's selling it. Buying it back directly from a Marktplaats listing or a stranger on the street is legally murkier than it feels: you'd be paying money for goods you already know are stolen, which can expose you to a heling (receiving stolen goods) question even though you're the original owner, and you have no real recourse if the seller just refuses to hand it over once they sense trouble. Confronting someone and physically taking it yourself can also flip the situation legally — you are the one who has to prove ownership after the fact, to police who cannot adjudicate that on the pavement, and a scuffle over it can land you with an assault complaint regardless of how solid your claim actually is.