There has been less snow in the mountains this year and I think the road will open earlier. You should contact the ski resort next door (+47 53654800) as they’ll have the latest information. Even if it’s closed, you’ll probably be able to cycle it, but ensure you do it early in the morning or late in the evening when there is no chance of bumping into the road-clearing crew. Worst case you can take a bus through the tunnels or cycle through late in the evening or early morning when traffic is very low.

I have cycled Nottoden to Kongsberg on the E134 once before because the detour on quieter roads was too long. It’s not a pleasant experience. No shoulder and plenty of cars travelling at speed. If you can head North and get on the quieter road to Kongsberg that will be more pleasant but longer.From Kongsberg it’s pretty straight forward on back roads to Drammen and Oslo.

The other option is to cycle down to Skien – Porsgrunn – Larvik and take route 1 up Oslo Fjord. This is considerably longer.