50cm is a tad excessive I think.
I do have a 50mm stem on the GTB. And a 50mm hi-rise Technomic on the Bridgestone XO-3. I didn't notice any change in handling.
This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.