The aim is to control the bikes over rocks and difficult terrain

The teenagers from Crickhowell, Powys, train practically everyday on their specially designed bikes on nearby rocky hills.

Lois Morgan, 14, has been womens' British champion for three years running and her brother Griff, 12, is second in Britain for his age group.

The pair are now preparing to head to Sweden to compete in a trial in the new year and in Japan later in 2004.

They train on seatless bikes which are similar to BMXs with 20-inch wheels, and have to balance across courses covered with rocks and rough terrain.

Their father, Gary said: "It is all about balance and control and not losing marks by putting their feet on the ground or crashing.

Lois and Griff train almost every day

"t doesn't take them away from their school work but it does mean that we have got to do a lot of travelling in the car.

"Homework gets done in the car, they sleep in the car sometimes we have to get up at five in the morning to go to competitions - it is pretty gruelling."

The sport has taken the children to France, Germany, Spain and the Czech Republic.

Griff said: "I don't really like football, I like bike trials because it's fun and you get to meet people from all over the world.

Lois, who was slightly injured in a competition in Rochdale, last weekend said the sport was exciting.

"It is quite dangerous, once I fell off and I hit my head against a tree and I had to finish the trial with my eye closed," she said.

"It can be scary with big holes and drop-offs but it is a lot of fun."