[sendler]

Thinking through the issue of side winds and motorcycle aerodynamics some more:
I question the theory of adding a long tail behind the rear wheel in order to improve stability. I know it is very aerodynamic and reduces wind drag from the front but will it make the bike track better in side winds? Adding a long tail makes the bike want to go straight through the wind like an arrow. So far, so good.
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Bikes don't turn from steering, they turn from leaning.
When a side wind hits the tail, it steers the front of the bike into the side wind. So far, maybe not so good. Bikes need to lean to turn, not steer. Does yawing the bike into the wind with the fin (rather than leaning) load the trail of the front steering geometry to cause a counter steering event that actually leans the bike the wrong way. Probably.
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Is the wrong way lean more than the right way yaw? Don't know.
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Another draw back to the rear fin is the sheer increase in area for the side wind to push on. Does it increase the ability of the wind to skid the whole bike to the side all at once? Definitely. The wet roads that I ride on half the time would be revealing.
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Does any increased fin area that is sticking up higher than the cg of the roll axis, ie a rudder, blow the bike over to lean the wrong way. Definitely.
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For motorcycles, keep your bodywork as small as possible while preserving low drag from the front. And the side. And keep the center of pressure from side winds as low beneath the cg as possible to help the bike lean into the wind the right way. And keep your cg high.