Brain only comes in standard "oversized" dimensions whereas Genius has more options in terms of tube shapes and sizes (although about 90% of the Genius frames out in market use the same external tube dimensions as Brain). Genius tubing is killer thin thus it will build into a light, but somewhat flexible frame. Brain is significantly thicker and more suitable for rough use, or if you want a stiffer frame than Genius will afford. Both good tubesest, but different.
Last edited by Nessism; 12-16-07 at 10:27 PM.