Paul, one of my buddies runs a bikeshop at the Chiemsee (1 hour ride away from Munic), which is a great area for mountaibiking. He got bikes for rent and sure can give you some 411 about great trail.
Here is is website [url:1epqsqiu]http://www.chiemgau-biking.de/servus/[/url:1epqsqiu] or write him at [url=https://www.facebook.com/chiemgaubiking?fref=ts:1epqsqiu]Facebook[/url:1epqsqiu]