motorbike carrying on towbar hitch

You've got to be kidding right? why all the calculations?
You do not need a WDH for a bike carrier therefore I would assume that if you have a max towing capacity of 1800kg you can have a down force of 180kg?

Why calculate the force applied of a bike being dropped from 200mm, surely the same would apply to the downforce weight being applied from the drawbar of a van, trailer etc?

I have been using one of these carriers for years on the back of different vehicles for years and never had a problem, except with overhang which was the OP's question.

Chris

Chris

Of course you can't use a WDH with a bike carrier but I am trying to explain what happens when weights are hung off the end of cars. The light weight utes like Tritons, Hiluxs etc are noted for suffering chassis damage, Cruisers and Patrols seem to be able to get away with it. The forces generated by all moving weights do exceed their static weight. It makes no difference whether it is on a tow ball, roof rack or anywhere else. When you mount a bike that far behind the axle, you are right up into the danger zone. The risk may be minimal on sealed roads but not off road.

My car can have 180 kg placed on the tow ball but not without a WDH, unless of course Toyota engineers do not know what they are talking about. The weight of that bike and its carrier will exceed the factory limits if this car in question is the same model as mine or earlier.

The WDH should only apply to long trailers like caravans though. They are a nuisance in many of road situations but then box and camper trailers don't need huge ball weights due to their short length with all of their weight close to the axles so it should be easy to design them with no more than 80kg. I could then tow one without any problems without a WDH even if it weighed well over a ton.

Chris - the carriers are not illegal. Legality would be dependant on the vehicle it was fitted to. I've seen them fitted to a Coaster motorhome and measurement satisfied the 60% rule. Vehicles like the Landrover Defender 110 , Ford F250 and Jeep Patriot have long wheelbase and very short rear overhang and could most likely also satisfy the 60% rule - but a Hilux with a tray that already extends far beyond the towball wouldn't.

There is a multitude of equipment sold that is quite legal - depending on the application. Eg - air horns, wheel spacers, aux and replacement lighting. All are OK for offroad use - but not on road where limitations are set. HID lights used on road MUST have a levelling device fitted. Thats the law - next time you are blinded by a vehicle with HID's - it most likely doesn't have a levelling device.

We've all seen the changes in bullbar design to improve pedestrian safety - then also see fishing rod holders permanently attached to the bullbar! Can you imagine the consequence of hitting a pedestrian or cyclist with a fishing rod holder - they would have 4 large holes punched through them!

Toyota are having issues with post 2005 hilux models fitted with steel bullbars and winches - it overloads the front suspension, and there have been many suspension failures. There is a thread on this forum about it.
Are bullbars and winches illegal? No - but if the fitting then makes the vehicle over spec on the front axle there IS an issue.

So it isn't only the legality of the item - but the application that it is used in.

Polaris

Your link (which incidentally doesn't work) does take you to information which confirms the 60% rule that I previously posted - in Qld anyway. I'm sure that investigation of other states will be the same as it is based on an ADR - which imported vehicles must comply with.

eg - Victoria.

Victoria overhang limit

For those who also had problems with the link, I have copied the relevant information from the Qld Transport website - .
"Rear overhang 'R' - No more than 3.7 m or no more than 60% of W,
whichever is less"

Polaris