so i havn't got to much help at a couple other forums on here and i just found out about this one, i am 300 lbs i'm getting back into biking to lose weight after almost 10 years without doing any serious riding.

i need help finding a good bike to buy, i live in eastern canada what are some bikes i should consider, i've been looking at a trek marlin single speed, and norco katmandu. i need a strong bike i want to take it on old fire roads and stuff so it'll be taking a good beating, i have a limited budget of about 600 max, and that is where the marlin is at but i do not know much about it, the katmandu looks real strong but i want a single speed i think