The incident happened yesterday (7/8) at about 10.30am on a path near Mill Lane.
The victim, a woman aged in her eighties, was walking when she saw a man on a bicycle who then exposed himself to her.
The offender is a white man aged in his mid to late thirties. He has fair hair and was wearing a dark jacket, combat trousers and dark trainers with white soles. He was carrying a large backpack.
Investigating officer, Sergeant Ryan Powell, based at Maidenhead police station, said: “I would like to speak to anyone who witnessed this, or who recognises the description of this man.
“It is possible that this incident is linked to other similar incidents which have been reported in the past 12 months.
“I would advise members of the public who are out walking in this area to ensure they have a phone on them in order that they can report it quickly if anything similar were to happen to them.
“I would also like to reassure people that we are doing all that we can to identify this man.
“If you have any details which relate to this particular incident, please call Thames Valley Police on 101, quoting reference number 43210352672. Alternatively, you can call Crimestoppers anonymously on 0800 555 111, or make a report online.”