Two days sufficient for one way, four day needed for return trip.
Bus "Time-ekspressen linje 1" from Oslo to "Kongsberg Knutepunkt", dep 5 am (Mo-Fr only!) am, 90 min
Bus 420 (displaying "Geilo") departure 7 am (Mo-Fr only!) from "Kongsberg Knutepunkt" to Geilo, 3 hours 30 min.
Bus 991 (displaying "Eidfjord") departure 11.45 am (Mo-Fr only) from Geilo to Øvre Eidfjord, two hours.
Bus 991 (displaying "Bu" or "Kinsarvik") departure 7.15 am (Mo-Fr only!) from Øvre Eidfjord to Bu terminal and here a immediate bus connection to a bus displaying "Odda" (just tell the driver that you'll continue towards Odda and he'll handle the bus connection). Stay off at "Tyssedal, veikryss (=road intersection) Skjeggedal", about 9 a m.
Find the road towards "Skjeggedal" and and start walking. 7 kms/4.5 miles from the road intersection you'll find a parking area and the trail start. From here a return trip is MINIMUM 10 hours of hard walking (the word "hard walking" used in Norway, means HARD!), signposts shows distance walked and distance left. Map/compass (and ability of using it!) compulsory! Free tenting in the Trolltunga area (max two nighs), just get 500 meters (550 yards from the trail, take 100 % care of nature and CLEAN UP!
Bus return from road intersection is at 8.30-8.35 pm (Mo-Fr only), bus displays "Granvin". Stay of at "Bu Terminal" about 10 pm. Bus displaying "Øvre Eidfjord" departure 10.50 pm, arrival in Øvre Eidfjord 30 minutes later. From Øvre Eidfjord bus displaying "Geilo" dep 9 am and arr Geilo 11 am, bus displaying "Kongsberg" dep 2.15 pm and arr "Kongsberg Knutepunkt" 2.15 pm. Fom Kongsberg Knutepunkt bus at 6 pm and 8 pm to Oslo. All routes Mo-Fr only!
Øvre Eidfjord has a small hotel (phone +47-5366-5346, sing/dbl NOK 690/980, three huts with two sgl beds, NOK 480/hut, +75 NOK/person extra if not showing your own bedding, sleeping bags not allowed). In addition there is a campsite (phone (Jun-Aug only) + 47-5366-5927), tentground for your tent NOK 160 NOK/unit + NOK 25/pers, huts four sgl beds NOK 670-1100. 100 NOK = abt 14 USD. Pre-booking accomodation needed, no bus booking needed/possible. over 3 years agoAnswered by Norway via WorldNomads.com