Like it says, you'd need to be careful you dont exceed the nose weight limit of your car. Note that none of the detail pics show a decent sized sports bike on the carrier!
Providing you have the right 4X4 or larher car then they are not to bad a idea. The RSV aprilia shown in one pic must be around the same weight as a 748/916/996/999 etc so they should be up to the job especially if its a Desmo Due race bike that needs to be transported.
Had a Mountain Bike carrier that fitted to the tow bar of my car, and it was limited to 60KG!!
I know that it's not even close to that of a sportsbike, but it still lifted the nose right up. Plus I'm not sure about how save the towball would be able to handle about 180kgs of speedmachine!!
My personal opinion is that it would be too dodgy!!!
Dry weight of a 996 is just under 200kg, the towball limit on a Shogun Sport (much the same as a Warrior) is 110kg so don't think it would work. How about a folding bike trailer, there are some really neat ones on the market which will fold up and fit in the boot of a medium size saloon car (obviously not with the bike on )
Maybe you could turn the whole thing around and push a Morris Minor at 140MPH with your Ducati.
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I like the idea of that even less,the bike will still have some tipping motion I imagine and all those forces acting on the front wheel and tyre .... and i imagine you'd end up "dragging" the bike about ....