I've done a round trip before using my foldie
I cycled from Medan to Brastagi and to Tuk tuk. Stayed a few nights in Tuk Tuk. Coming back, I took a taxi from Parapat to Medan and flew back to Penang Malaysia, the same day
I'm thinking of doing this bikepacking trip again...
Day 1 - Fly into Medan, cycle or take a taxi to Permatang Siangtar, stay a night
Day 2 - Cycle to Tuk tuk from Siangtar via Parapat. Stay in tuk tuk for few nights
Day 3 - Cycle to Brastagi from Tuk tuk
Day 4 - From Brastagi cycle or take a taxi to Medan
http://bikelah.com/index.php?route=information/news&news_id=3260 
