Our personal favorite and by far the fastest and most affordable way to get around the city. Bikepath facilities are excellent and summer weather makes biking very pleasant. The closest place to rent a bike from is Rijwielservice Weesperplein, you can rent a bike for only 12,50 a day but you do need to reserve the bike in advance because they run out quickly: http://rijwielserviceweesperplein.nl/index.php/bikerental/.
The University of Amsterdam has ample space to stall your bike. It can be a good idea to first check out the local road rules. The ECPG and local organizers cannot be held responsible for any injuries.