Hi, Have just come back from a trail riding holiday in Romania and can't recommend it enough !, the most trail riding I have ever done in a week on the most varied terrain, this was a guided tour from Adventuromania, you can use your own bike, or like I did hire a bike off them, if you want endless trails all day long with not a fence or gate in sight check it out, the riding is tailored to your level upto expert enduro riders and based in the Carpathian Mountains there's no shortage of spectacular scenery. Check out their website
http://www.adventuromania.co.uk/ cheers
Dave