Is it necessary to buy IC card in Handzhou? What are the advantages?

Without the card, you cannot rent a local public bike for riding, but it will affect taking buses and subways. Cash can be used on the buses and you can use cash to buy the subway single tickets.

If you do not plan to use the public bike, it is not necessary to buy an IC card. Or you can purchase a Z card for renting bikes only and use cash at other places.