A dirt jump bike is essentially a cross between a BMX and a mountain bike.
They tend to have lower more sloping frames, a much lower seating position and also tend to run single speed and with a single rear hydraulic disk brake setup.
They come with 26″ wheels and front forks as standard.
Quite a few of our BMX riders now have dirt jump bikes and these can be used within the BMX sessions although we do still advise using a BMX at the sessions as it allows a greater amount of learning of important skills.