It's not how fast you can go, it's how fast you can stop.
If you can come to a full stop in 10-15' your good.
NO MOTORIZED BIKE IS SAFE OVER 20mph WITH JUST A COASTER BRAKE!
This build flirts with 50mph but it has the stopping power...
That sucker stops in a heartbeat with those dual disc brakes and 3" wide tires.
Just remember this...
It's not a matter of
if something will get in front of you forcing a panic stop, it's simply
when, and
how often.
For you young guys...
Take it from a guy that 'played hard' his whole life and got banged up but healed quick...
Well, my theory is your body remembers each and every trauma, then switches all the pain receptors on when you get old.
Just ride safe and protect you're body, it will be worth it when you get older ;-}