Hi Patricia, if you are planning on leaving Bergen in early May, you basically have two options.
The coastal route or a mixture of both coastal and inland areas. Manyy of the famous mountain roads don’t open until late May so it’s hard to plan a mountain route that early.

Coastal: http://www.ridewithgps.com/routes/39267512?privacy_code=fYonryshba76jGZX (From Trondheim, you basically follow the Eurovelo 1 to Nordkapp).

Mix route: On this route, once you reach Ålesund, you will need to check to see if Trollstigen and Aursjøvegen roads are open. If not, you’ll need to stick with the coastal route to reach Trondheim: http://www.ridewithgps.com/routes/40031080?privacy_code=eMyAk8MyKtpYKMjM

Use this page to check opening dates: http://www.cyclenorway.com/opening-closure-of-roads/

If you plan to start from Oslo you can take National Cycle Route 7 or 9 in early May without any problems.