The bike was stolen from outside a premises in Marlborough Road at Lancing Business Park between 4pm and 4.30pm last Tuesday (October 26).
According to Sussex Police, moped riders were seen in the grounds of the premises at the time of the crime.
A spokesperson added: "The owner says the bicycle has a golden handlebar frame, black bodywork, and thick dirt road tyres.
"Anyone who witnessed the incident or who has any information about the theft is asked to report it to Sussex Police online or call 101, quoting serial 1228 of 26/10."
Have you read?: Police officer from Worthing suspended after assault charge