My son who is 15 years old rides a 250 pro in competion, has just won a season & has no problem in doing so. He is 5ft 7 & weighs about 8 stone.It' all about set up. every body is different. I ride a 280 & he has no problem with mine either.I think you should go to Gas Gas UK & get in touch with the GURU. You know it makes sense.