Use the bus, Harbour bus, metro and train in Copenhagen.
Buy a Copenhagen Card or Copenhagen Citypass
If you are going to see some attractions and museum that's the card for you.
If you don't care about attractions and museum. Much cheaper than the Copenhagen card
With a City Pass in your pocket you can take metro, train or bus to different sites and activities in Copenhagen. Choose between a 1-day or 3-day ticket and set your own pace.
No free admission to 79 attractions
Free transport in Copenhagen zones 1-2-3-4 (Airport included)
Ticket to public transport in Copenhagen delivered on your phone
Price around 27 euro for 72 hours
The city of Copenhagen now got more bikes than cars and 5.2 bikes for every car.
All over the City you will find Bike shop's who rent out bikes for a day or even for several months.
Maybe your hotel got bikes to rent or if you are lucky for free.
City bikes are available around most stations and main streets, but economically speaking, they’re better used for a few hours rather than full days. They’re also useful late at night or early in the morning (they’re available 24/7), or when you want to take advantage of their GPS system as you travel.
But be aware that the bikes are electric power, so if you are not used to bike, do not rent them. The bikes are fast, and a little bit difficult to drive.
And remember you can bring your bike for free in the S-trains day and night