Donkey Republic is a modern alternative to bike rentals or city bike systems. It is very easy to find and book a bike with the mobile App and unlocking bikes' smart-lock with the phone is super fast and cool. Also, bikes are gorgeous!
Bikes can be rented 24/7 and, differently from city bikes, don't have to be brought back to a hub every half an hour. Are sleek, very fast, and customer support is lovely! Also, I love to find Donkey Bikes when I travel in the major cities around Europe: Copenhagen, Barcelona, Madrid, London, Paris....
Renting a bike for two days will give the best quality/price ratio in my opinion