Question: How can a person ride a motorcycle 100 mph but not stand up in a 100 mph wind?

– not to mention a lower “frontal area” when tucked behind the bike’s fairing ( assuming it’s a sports bike ) .
It’s actually hard to hold onto the handle bars of the bike – for a reasonable time – at speeds of over 60mph without a fairing to smoothout the airflow.
When you are stood up, facing the wind, your “cross sectional area” will be huge, and your wieght will be the same as sat down, so you’d have a “critical wind speed” that makes you blow over. – same as caluculating wing area for a ‘plane. enough meters squared = flight ( or fall over )
Once tucked behind the bikes fairing, your body won’t add much to the bikes existing frontal area.
The other factor is the bike engine… it’s pushing you forward, so helping you, just standing in the wind,you have nothing to hold on to, nothing to keep you upright.
The bike helps again, with it’s built in centre of gravity being low down – my CofG is higher when I stand up, somewhere near my tummy button. ( Women’s CofG is lower, as they have larger legs than men do )
and again, the bike has yet more help for you… the gyroscopic effect of the 2 wheels spinning helps keep the thing upright, so that’s a huge help as well.
Vehicle dynamics isn’t my strong point, there’s all sorts of other thing you can calculate, such as minumim turn radius required and associated speed for a skid ( on 4 wheels) , or, take that further, you get the speed/curve req’d to roll the car. can do the same maths for a bike, just having 2 wheels makes it a little harder, as the bike leans more ! so lowers it’s CofG… so can corner faster…until…. it all lets go and the rider ends up in A+E ( or worse ) – you can also work out braking forces, etc etc and power erequiredform the engine to reach the 100mph

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