A guy told me about this bridge in Orange TX, it's like a steep mountain since it was designed to allow tall ships to pass under.
People used to bring their bikes to the top and try to see how fast they could go down it. The tires and bearings of a bike aren't designed for that high of speed, so tires we're blowing out, hubs were exploding, etc. They ended banning bikes from the bridge for this reason.
Keep in mind, bike companies design bikes to be as light weight as possible. They choose the best balance between strength and weight. It's not like an SUV where things are designed to withstand the beating of a cocaine soccer mom. Motors and high speed were never part the plan when making the bike.
If you want to go that fast, get a 125CC motorcycle.