For men they can wear what they wear in their country. They can wear shorts as well but we recommend it to be at least above knee and not too short. For ladies, they should cover their hands and legs as well as their hair. This is especially necessary when you are in the society in towns, villages or rural areas. Please check a couple of our cycling tour videos to have a better understanding of the clothes you can wear for traveling to Iran. For more information, please have a look at the below LINK: