Folks, here's some routes that I travelled when I was in South America. I laid them out for some friends going south, so I may as well share them here too. These are 3 mainly dirt routes in Colombia, Ecuador, & Peru, and they're all fantastic. These could be well known already, but sure I'll stick them up anyway. Hope they'll be of use to some of ye.
Colombia
Popayan - San Agustìn - Tierradentro - Popayan
This is a gorgeous little route, mostly over dirt roads. 5 days with 2 days spent between San Agustìn & Tierradentro to view tombs, statues & countryside, but of course it can be done in less. The Road between SA & Tierra is paved for maybe 70km's, then back to dirt. In some parts it gets pretty muddy if it's rained. Also, watch out for FARC on the way to SA from Popayan.

On the route to Tierradentro from San Agustìn, when you are getting close to Tierra you come to a river (I can't remember the name, need to see a map), and you have two options to proceed....one is an hour detour to the left up the river, the other is over a bamboo bridge. Here's a clip from another lad that did it. I've gotta say he did a better job than me, I had that ****er swinging....
YouTube - 10. Un-cut Brainrotting footage: Crossing the bamboo bridge in Colombia
Anyway, the choice there is your own, but the bridge is an experience. Might I suggest unload the bikes first, then walk them over...!
Anyway, gorgeous route.
Ecuador
Quilatoa Loop
Gorgeous dirt road loop around a volcanic crater (Lago Quilatoa) and the surrounding countryside, in the highlands south of Quito (just to the west of Cotopaxi Volcano). This could be done in a day if short on time, but 2 is nice. Plenty of places to stop and sleep. Watch out for the dogs, craziest in all of South America.
Peru
Cordilleras Blancas
Take the highway south from Trujillo. At about the 81km mark you will find a dirt road leading to the left, east, with a sign saying: Proyecto Mankowitch Bocatoma. Take this dirt road for 22km's until you reach Tanguche, keep going east. After this you will find a bridge with a gate on it. Look around for the security guard to unlock the gate on the bridge and cross the river. Carry on east to Chuquicara. Here you will find a gas station, maybe not a bad idea to top up. Just after town are some cops at a barrier who will leave you through. Ask them for the road to Cañon del Pato or Huallanca. It is a dirt road, do not take the alternative paved road. The dirt road passes through a series of tunnels (40-something I think) with gorgeous views of the canyons and hills. A side trip on the way to Huaraz is up to the spectacular Laguna Llaganuco, in the Parque Nacional Huasacaran. Another extension of this trip is to Chavìn de Huantar (possibly my favorite little town in the Andes. It is very real.), on the other side of the Cordilleras from Huaraz, reached by going south, east, then north on the roads (there are alternatives, this is just the way I went...). Don't miss Lago Quanchenca on this route. All this is probably my top route in my trip so far, absolutely gorgeous. I had no problem camping out, felt safe. Never ran out of fuel, though I was sold some mixed with water in Chavìn de Huantar. You hit up some high passes and it gets cold at night. I took about 4 days I think to do it, but could be done at a quicker or slower pace. Really shouldn't be missed if you have the time.