carbon fiber sheet. This shit looks really nice and it's stronger then the alu plate. I've cut this sheet in 2 pieces and mounted 1 on top and 1 on the bottom.
Before I had 1 alu plate 2mm thick. But an alu plate tends to bend on hard landings. No I have got 2 x 1.5mm (25cm long, 5cm wide) carbon and that is a lot more stiffer and will not bend on a hard landing. And this gives me only 10 grams more weight. That's almost nothing!
Download the frame in Google Sketchup 3D