I would still like to see a failed Al stem or at least a link to one.
The way I see it, first you need to figure out the tensile of the Al alloy used and the the weight of the small tube sticking out.
Then with that info you could figure out how fast the wheel would have to spin in order to cause deflection of the tube.
I would guess the RPM needed to cause the tube to bend would be higher than this bike is capable of producing.
I also find it a bit odd that the aftermarket wheel manufactures don't know about the dangers of 90* stems..... I mean why would Marchesini put 90* stems in their ad photos?
http://www.marchesiniwheels.com/en/whee ... enesi.aspx
They also sell them directly:
http://www.marchesiniwheels.com/en/whee ... ORIES.aspx
BST, the same thing....90* stems
I could go on but I just leave it at that, Until I actually see a 90* valve that has failed due to it flexing itself apart, I just can't believe it.
Plus the fact I have run them for years on my bike ( and yes it has reached its terminal velocity or around 160MPH during that time) with no issues what so ever.
Then I would say around 80% or more of the club racers in the Bay Area also run them and I have never seen one fail.
Loud pipes don't save lives, knowing how to ride your bike will save your life.