I've been in the Peruvian and Bolivian Andes, and have toured in the (lower altitude) Guatemalan Highlands so I know the grades (and the altitude!). Depending on your the load, I think you may want the low gear-inches in the very high teens, very low twenties range. The common unsurfaced roads add friction and zap momentum on uphils so you want to be prepared for spinning seated rather than mashing or relying on standing up.
See my three options below.
Originally Posted by
gagepo
Hi Abu. Thanks for your reply I'm currently running the stock 11-28. Yeah I'm being intentionally vague about exact GI ranges mostly because, honestly, I'm new to this and dont understand it all. I'm more concerned about making sure that I can fit these parts on the bike and peoples opinions on said parts and compatibility with the Tern D8.
The Shimano XT 11-36 also comes in 11-34, 11-32, and 11-28. I just know I need a bigger top gear for spinning up the Andes! Not exactly sure which one would be perfect.