Have a look at the "onyerbike" range of folding mountain bikes. http://www.onyerbike.com.au . I looked at the Dahon (Matrix) and Montague (Hummer) but chose a Terminator 2 from Onyerbike as it had dual suspension and better components. I've had it for 2 years and done plenty of off road riding. They might be a little difficult to get if you live outside Australia as they are an Australian company.
Have a look at the "onyerbike" range of folding mountain bikes. http://www.onyerbike.com.au . I looked at the Dahon (Matrix) and Montague (Hummer) but chose a Terminator 2 from Onyerbike as it had dual suspension and better components. I've had it for 2 years and done plenty of off road riding. They might be a little difficult to get if you live outside Australia as they are an Australian company.