Super Brevet Scandinavia is run under rules and regulations very similar to the ones applied to Paris-Brest-Paris. The main points are listed below and at the bottom of the page you find a link to the full text:

• The bike must only be driven by muscle power
• Special bikes of all sorts are very welcome, as long as they comply with the traffic rules
• Tri-bars / extended bars Handlebars extensions are allowed only if they don’t extend beyond a line created between the front of the brake levers, which must not be pointed forward.These bars may not be used when riding in a group
• The bike must be fitted with adequate lights for driving at night and during the day under poor light conditions
• The participants must wear a reflective west when driving at night and under poor light conditions
• To wear a helmet is compulsory in S-B-S
• To offer or receive support on the route outside the controls is forbidden, but allowed at the controls
• Participants are allowed to help each other on the route
• Traffic laws of Denmark, Norway and Sweden must be respected
• Directions of the organizers must be respected and followed
• It is not allowed to throw litter on the road
• Controls must be passed within the time limits stated on the brevet card
• Finish in Kristiansand must be reached within 90 hours

The organizers can penalize violations to the rules by adding a time penalty to the overall time.

You'll find the full text of the rules by following this link (pdf).