Trials bike will be purely for trials, but for 1800, i know alot of bikes that are light enough to do trials. Giant STP 0 (Full Bike), that's like 1200, and it's less than 25lbs. Banshee Amp or Morphine (Frame), Da Bomb Molotov III (Frame), Trasition Trail/Park(Full bike or frame, less than 25lbs full bike), Blk Mrkt Riot/Mob (Full bike or frame, is also less tahn 25lbs), all are light and excellent for freeride, dj, street, and trials riding.

Good luck