Phoenix363

I travelled through South America a couple of years ago (admittedly I was hiking, not mountain biking) and was also a beginner so took only my Canon 650D and Tamron 18-270mm F3.5 to 6.3 lens. The only time I really felt lacking was in the mountains around Colca Canyon in Peru as I just didn't have the reach to get a good shot of the famous condors there. I have included a shot below I took in Brazil that was using the wide end of that lens wide open at F3.5 and I didn't have too much trouble capturing in the low light. My suggestion would be to instead get the 30-110mm to go with your Nikon as it means you will have a large coverage and the 10mm end of the 10-30 will cover you off for the early morning/late afternoon sunsets and the long lens will have the reach to get in nice and close for wildlife etc. that you may meet along the way. (picture is of Ipanema Beach in Rio)