That was me in some of those photos in Cranked, Cass (whileoutriding) and I rode a good chunk together last year following the Andes.
I'd say the most accessible mountain bike tours are in the Cordeillera Ausangate (near Cusco) and Cordeillera Blanca. The Cordeillera Huayuash is a little bit more difficult to get to, either 3-4 days ride out of Huaraz with a big climb to get you to the starting village or a long bus journey.
Huaraz is relatively high (> 3000m) so you will need a few days acclimatising if you are coming straight up from Lima, but it a comfortable city with lots of tourists and with it gringo eateries and the like.
Depending on the amount of time you have you could explore around Huaraz, and then ride the Peruvian Great Divide down to Cusco and maybe even on to La Paz. That region contains some of the finest bikepacking in all of South America....I should know because I rode the length of it!
Wherever you decide to head Peru is an absolute mecca for dirt touring so will will undoubtedly find some amazing riding.
A word of caution, the Inca trail out of Cusco is very difficult to access by bike, given the Peruvian governments attempts to milk that cash cow. Unless you are a walker you have to be very covert about it, and possibly ride at night.
It's possible to buy gas in Huaraz but its expensive. Petrol, or Alcohol are better ways to go. Alcohol is available virtually everywhere, given the locals drink it!
More of my trip on:
www.mikehowarth.co.uk.
If you have any specific questions, drop me a message through my site.