My butt likes the Flite shape, but this model is at least 100 grams, if not more, lighter than my current 4-year old Flite Gel seat. But, is it intended for road only? I'm worried about cracking the rails if I'm sitting down through a bumpy part of a trail or something. Any of you guys use one? I tried the SLR, that flat shape does not agree with my butt-parts...