first of all it looks great

as for functionally, it has 2 purposes. the first and original one is that at triple digit speed it reduces the drag created by the rear wheel by a few hundredth of a percent.that's caused because the relative speed of the wheel and air on top is the combination of actual bike speed and wheel rotation speed. once you put the hugger the oncoming air only sees th hugger and the wheel itself.

the second and more relavant for us commoners is that it protects the rear shock and electronics from the dirt thrown by the tire.

did I mention it looks great ?

 

Mostly for looks and to keep your undertail clean.

 

Cool; thanks!

 

So got a chance to see about the fit for the rear hugger today. Forgot to take pictures though. The hugger needs to much work to fit, so I don't think it is worth it. I will fit an RR, but the linkage or our swingarm is in the way, plus the chain.

 

a hugger designed for an F4/F4i needs too much work ? it doesn't need any, especially compared to fitting an RR hugger and drilling the swingarm.
you do however needs to temporarily remove the pillion left footpeg to get the hugger in place.

friday I'll have a chance of getting some photos of my bike in day light.
until than I strongly suggest don't bother with the RR one.

Avi

 

Whaaaattt???!!!

 

No, meant the one in the picture that started this tread. And f4 specific one would probably fit.

 

ok, it seems much clearer when you are an aerospace engineer

think of a flat plate laying down on the floor with wind over it. this will obviously produce drag. the stronger the wind the more drag force there is. if the flat plate is moving in standing air, it is still the same. it is only the relative speed that matters.
now imagine the flat plate is the top of the wheel. the wind is the speed of the bike, but remember the wheel is spinning and the top is moving forward relative to the bike, so both these speeds add up.

so why place a fender or hugger?
all aerodynamic forces are proportional to the speed squared.
so if the hugger deflects the air off the wheel, the oncoming air only faces the bikes speed, and the rotating wheel only sees the air trapped between it and the hugger.
in this case, we actually seperated the case of the wind over a standing plate, and the case of the moving plate in still air.

and does it reduce drag ? remember the drag raise by speed square. so the sum of V^2+V^2 is not the same as the case of relative speed of 2V which when raised by the power of 2 becomes 4V^2.

I hope this is more understandable.

and just in case it isn't, the point is that if you are a good track rider, you can gain a few hundredths by installing a hugger

cheers, Avi

 

as promised
the hugger came off an F4i, and mine an F4 2000

 

Hopefully my picture worked, i have a carbon fiber one on my f4, got it for 15 quid off ebay :P totally one off, but the one you showed looks a bit meh :P