nowhere. no one is going to be liable for you going out and hurting yourself. you may be able to find a guided tour and rental but there definitely wont be any extremely difficult trails or jumps in your future. it takes years of day in and day out practice to become an expert rider. you cant just go out and rent a bike and turn pro. you're much better off saving your money and buying a bike, that way you can take it slow and learn at your own pace, wherever and whenever you want. if you have the dedication it takes, you'll be very happy when you finally become a good rider or racer. good luck!
