The man allegedly grabbed Alfia Barnett's handbag as she stood on the doorstep of her home in Highbury Street,  Peterborough, before making off on a bicycle.
The pensioner was left with minor injuries after the incident, which happened on 13 July at about 11:45 BST.
Cambridgeshire police are continuing to question the man.
A man has been arrested after an 84-year-old woman was robbed of 50p.