Some more videos for you:
Best of Oslo (made by some wacky swedes):
http://vimeo.com/111921324 Lots of it takes place around Grefsenkollen (
http://mtbmap.no/#15/59.9576/10.8114 )
And the view from the top is like this:
http://vimeo.com/78283179 is filmed around
http://mtbmap.no/#14/59.9738/10.6933 A video roundup from last years XC race "terrengsykkelrittet" which takes place in late May each year:
http://www.fftv.no/terrengsykkelrittet-2014 ( area:
http://mtbmap.no/#14/59.8693/10.8893 )
One difference from Canada, depending on where you live, is that there are almost no built trails in Oslo (or in Norway as whole). There are a few exceptions, but the norm is natural trails, which can be technical and rough in some parts. They are also shared with hikers and going riding midday on a nice-weather Saturday and Sunday can result in heavy traffic from hikers, especially on the trails closest to residential areas. But go early or late or pick trails further into the forest, and you're good to go.
You can even bikeshuttle by subway in the north forests :-)
And speaking of subway. 10-15 minutes by subway in both northern and south/east directions get you close to quality trails.
And if you crave for bigger mountains, you can travel a handful of hours and get proper mountains.
