Hey my names dave and welcombe to the trials forum .....Ok i my self would advise you to get what we call a mod trials bike.Mod bikes have 20 inch wheels and in my opinion are much easier to learn on .They are much flickier that what we call stock bikes.The stock bikes are the bikes witch have 26inch wheels. For 300 pounds im pretty shure that if you gon on tartybikes.co.uk you will find something thear . I my self ride a mod bike and im about 5feet 7 inches tall.... Any more help just ask Dave x