I sort of recognise those dropouts, if that doesn't sound strange... The word Sandvik is there in my head as well. I've a feeling the frame is about 10+ years old, the rear brakes have a stop for center pull cantilevers. I'll keep thinking . Btw, $100??? - BARGAIN! Also, the stickers looks like it may be a Kona sticker, maybe given away on the front of a mountain bike mag.