To all you 29er's out there!

She's looking good. 140mm rotor on the rear?

Yep, I'm a weight weenie XC type (the bike is around 8.5kg I think). So I've gone 140mm on the rear. Should still lock up the rear wheel fine. If dont like it, I can just replace it with a 160mm. I will be going 160mm on the front.

Umm... did I mention I know nothing about disk brakes? It wasn't until I put the front on that I started thinking maybe I could do with going down a size! At least a rotor won't break the bank. What's your thoughts on a good size for a little downhill and general XC?

160mm is standard xc fodder. But there's nought wrong with 180mm (yours look like 180s to me)