I was reading up on the Forth Bridge and found some items to be interesting...
63 men died building that bridge
190-200 trains cross that bridge every day. If my math is right, that's approximately one train every 7 1/2 minutes.
75 people previously died in the Tay bridge disaster over the (Firth of Tay) which resulted in the over engineering of the Forth Bridge.
It's not the limits of the bike... it's the limits of the rider on the bike.