Originally Posted by
Mike Mills
Well, actually, all other things being equal, the sloping top tube would be less stiff than its shorter cousin (the level top tube). This is due to the extra length which, as you may know, is a major driver in stiffness.
This is dependent on ST angle, if I'm not mistaken. If we're making a frame with a 90 degree ST, then the sloping tube would be longer, for sure. On my Mongoose, a hypothetical horiz. TT would be approx a 1/4" longer than the sloping one it was born with.