Maybe rain gear and goggles would be less affected by cross winds? Anything that promotes cycling I am all for if it's practical and safe.

A solution looking for a problem: A good rain cape is a simpler, cheaper, and more protective solution:
http://cycleking.co.uk/uploaded/thumbs/thumb3_BC750.jpg
Combined with gaiters and good rain shoes, I've ridden whole days in the rain while still perfectly dry underneath.

Could be fun with a good strong tail wind (and good brakes) but really hard work in a head wind. Beinteresting to find out how much visibility the rider has after riding on wet city roads for a while. Car windscreens can get very dirty, but have screen washer/wiper systems, and bikers have sponges for ther visors.

This is hilarious, A sail for a bike, that looks like it attaches to the rider ? Thats going to make for a nice body slam, that will rival something you would see in Pro Wrestling. good news is you can now text without getting your phone wet too. This bike umbrella idea might work better if the seat is removed.

And when the wind catches this umbrella it throws you in front of a car, your dead. No thanks.

So...you will just be soaked from the waist down?

Will this actually keep the rider dry? ...or would rider still need to wear raingear? If latter then why bother?

This hair-brained idea came up many years ago for motorcycles. Didn't work then either....

"...aerodynamic to the point that winds of up to 80 km/h (50 mph) will cause no issues." I don't think so. 20 mph maybe. Besides, having half your body soaked isn't much different than being all wet.

In past decades Piaggio, Peogeut, etc produced accessories like. For bicycles is a different matter: there is the problem delvento front and side; the rain side. This solution then holds up the gusts of wind? And 'much better to have adherent capes. I would have built a smaller windshield It is a sail!