Cycling from Riberalta to Porto Velho – estimated distance 425 km, pace 75 km/day, duration one week.
Then paddle on Rio Madeira until Brazilian village of Borba (south of Manaus) – estimated distance 880 km, pace 30-35 km/day, duration four weeks.
Optional - walking with the guide through the jungle to Manaus - distance 200 km, approximately pace 10-20 km per day, duration two weeks.
Problems arise between the Bolivian Riberalta and Brazilian Porto Velho. On this river stretch there are 18 rapids, too risky for unexperienced paddler as I am. It seems that this 450 km stretch from Riberalta to Porto Velho I'll have to cover on mainland, probably by bicycle. I'll have to sell a boat (or arrange its transport to Porto Velho), buy a bike and ride 450 km to the Brazilian Porto Velho. I don’t think this road is paved, so it depends also if it will be passable (dry season only). I don’t know either whether it’s possible to cross Mamora border river with no motor (between Bolivian Guayaramerin and Brazilian Guajara-Mirim).
In any event, from Porto Velho river is again suitable for rafting. I have few options over there:
Option 1 – sell the bike, collect my boat (or buy a new one) and continue paddling to the north-east. The initial plan is assuming reaching Borba village, where maybe I can find a guide who will lead me through the jungle to the Amazon River, just near Manaus. But I don’t know whether this is real or not, even if the ground is suitable for walking? However, if I don’t find out I'll have to continue rafting further on and connect to the Amazon River near the town of Itacoatiara, where I would have to return to Manaus, 270 km on land. Unless paddling a bit on Amazon River, but against the current.
Option 2 - all the time I will ride bicycle, from Riberalta, via Porto Velho, to Manaus.
We'll see. Useful information would be report relating safety on this section, in sense of danger from river or road pirates for solo travelling gringo. Please advice if you know any good or bad stories.