Oslo City Bike have mechanics who will help with adjustments and minor repairs. The Cyclist association share advice and bring prizes. There will be a washing station with everything you need for a sparkling clean bike and a DIY station with tools for pumping, adjusting or lubricating.
There may be some waiting time at the workshop and washing station.
Maybe you don't have a bike, but are looking for one - then you must show up to participate in the draw for 2 refurbished bikes!