After a short Google search I came across the backpacks of Cabin Max, mostly seem perfect for my purposes, since they are beyond even exploit the baggage dimensions of German Wings accurate and yet very light.
With this backpack I flew last week for the first time - how appropriate - to Barcelona. It is unbelievable what all fits in here. The backpack was almost completely filled (only almost, because I wanted to have in Barcelona perhaps a bit of shopping), yet I had long since reached the weight limit of 8 kg.
At the processing I could - in contrast to some other reviewers here - fault anything. So far nothing is cracked or worn. Very handy are the 4 straps with buckles (outside each two right and left) with which you can re-tighten the boot with good filling and bring order back to the correct dimensions.
The Comfort also will not miss out; Despite the size, the case thanks to the good back padding is still comfortable to wear.
All in all I am very satisfied and would recommend this backpack every city travelers. Especially for the price, as just worth nothing expensive.