I have ridden a road bike for several years. I was in an accident awhile back and can no longer ride a road bike comfortably. I have no desire to ride off road, but need something that allows me to ride in a more upright position. My problem is I like to go fast. The mountain bike and hybrid I tried are nice bikes, but seem to be heavy and slow. Does anyone know a way to convert my road bike, if possible, or have a suggestion as to an alternative.