motorbike carrying on towbar hitch

Submitted: Friday, May 25, 2012 at 08:38
ThreadID: 95793 Views:10692 Replies:8 FollowUps:4
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Hi, I have a trayback Hilux with a 50mm*50mm towbar hitch socket 500mm forward of the end of the tray. It looks like these carriers will not have the clearance to come back far enoughhttp://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270980002549#ht_5602wt_1163 I'd also like to get more height to improve departure angle when coming out of sharp gully crossings. Is there anything available off-the-shelf to solve these problems, or do I need to get some sort of S-bend hitch extension to go between hitch socket & carrier? Regards.
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Reply By: Polaris - Friday, May 25, 2012 at 09:27

Friday, May 25, 2012 at 09:27
Be very wary before you go and buy such a bike carrier.

These things are used a lot in the US, but don't satisfy basic Australian Design Rules with regard to rear overhang. Similar situations have been discovered by people who have imported motorhomes and buses from the US or Japan.

The basic ADR requirement sets the maximum rear overhang as 60% of the vehicle wheelbase. In other words 60% of the distance from the centre of the front axle to the centre of the rear axle. Wheelbase and Track (front and rear) are usually listed in the vehicle specs. The 60% maximum is then measured from the centre of rear axle to the most extreem point at the rear of the vehicle. In the case of your proposed bike carrier, it would be measured to the rear most handlebar or the lower frame that the tie down is attached to.

Many buses and motorhomes have needed to be cut in half and had the chassis extended in order to be able to satisfy this measurement rule. Extending the chassis on your Hilux would be a way around it.

Another point to watch with extending the tow hitch is that it places a huge amount of leverage on the receiver hitch which often results in the 'broken back syndrome' - rear chassis bending upwards behind the cab. This can happen just by overloading the ball with a front heavy campertrailer. Adding air bags to the rear of leaf sprung vehicles compounds the problem as it moves the load carrying area on the chassis from the spring shackle mounts to the bump stop area...
AnswerID: 486732

Reply By: splits - Friday, May 25, 2012 at 10:29

Friday, May 25, 2012 at 10:29
Cybermike

A bike hanging that far back behind the rear axle is going to cause a lot of problems as Polaris has already stated. I don't know what model Lux you have but my 03 has a maximum towing capacity of 1800 kg. The handbook says to use a WDH if the tow ball weight exceeds 80kg. Any motor bike will most likely weigh more than that but you have to remember it only weighs that much when the car is stationary. The forces it will generate when the suspension is bouncing up and down on rough roads will be far higher than the static weight.

I just did a simple calculation on one of the many sites on calculating the forces in a falling mass and a 130 kg bike falling 200 mm hits the ground with a force of 260 kgf. That is just a rough calculation and there will be a lot more involved when you include vehicle speed and spring compression instead of a straight fall but the forces will be much higher than the weight of the bike and its carrier. When you include the extra length needed to get the bike back past the end of the tray plus whatever weight you have in the tray behind the axle, your chassis will be screaming you have got to be kidding.

It will also swing the back of the car around like a pendulum if you ever have to take sudden evasive action at highway speeds. The effect on the car's handling will be even worse if you have stiffened the rear suspension only and not the front because this will increase its tendency to oversteer.
AnswerID: 486740

Follow Up By: Member - Chris & Debbie (QLD) - Friday, May 25, 2012 at 11:49

Friday, May 25, 2012 at 11:49
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
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Follow Up By: splits - Friday, May 25, 2012 at 12:51

Friday, May 25, 2012 at 12:51
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.
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FollowupID: 762009

Reply By: Member - Chris & Debbie (QLD) - Friday, May 25, 2012 at 12:30

Friday, May 25, 2012 at 12:30
Cybermike, I have been using one to carry a motorcross bike for many years and can see where you are coming from with the overhang.

The only suggestion I have is to ring Hitchmate who manufacture a lot of different type of bike and cargo carriers.
I also do not understand how these carriers can be illegal as stated in another reply, if this was the case how do an Australian company such as Hitchmate get away with selling them especially when their site states
"And, It's LEGAL and COMPLIANT Australia-wide - it WORKS!"

Chris
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AnswerID: 486752

Follow Up By: Polaris - Saturday, May 26, 2012 at 09:32

Saturday, May 26, 2012 at 09:32
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
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FollowupID: 762028

Reply By: Dereki - Friday, May 25, 2012 at 13:28

Friday, May 25, 2012 at 13:28
Each state has a brochure to explain the rear overhang rules.

Queensland version.

http://www.tmr.qld.gov.au/~/media/062dda89-8811-431b-824b-0422672ded5b/pdf_projecting_loads_brochure.pdf

As explained above almost all rear bicycle/motorbike carriers are illegal on many family cars. My compact 1 bike carrier is only just legal on my Prado. But in reality, no one is going to care.

The problem I see is adding an extension to clear the tray is going put the tow hitch way out of spec. Remembering that the allowable down force using the standard length tongue. Double the length, halve the down force.
AnswerID: 486756

Follow Up By: Polaris - Friday, May 25, 2012 at 17:10

Friday, May 25, 2012 at 17:10
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
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FollowupID: 762016

Reply By: The Bantam - Saturday, May 26, 2012 at 18:29

Saturday, May 26, 2012 at 18:29
There is a repeated issue with almost all of the light 4wd utes.

The chasis and the towing capacity applied to them is designed without the tray fitted.

having the towball way under the tray is a constant pain......if you then fit a long hitch bar to the reciever the leverage is massivly increased.

I have a long hitch on my hilux, and it barely gets the ball past the end of the tray.

Y gona need at least 3 or 4 feet of hitch extension to get far enough back to load a bike on the back of a tray back lux

Have a look at the rear section of chasis on ya hilux.....it aint real heavy.

I have seen several photos and one example first hand of these chasis being bent just beyond the rear spring shackle on hiluxes and other light utes.

It would probaly be viable but with a tray that ended about level with the rear of the chasis, but only just.

A light high clearance trailer would be a far better option, if ya cant get the bike on the tray.

cheers
AnswerID: 486833

Reply By: Cybermike - Sunday, May 27, 2012 at 02:52

Sunday, May 27, 2012 at 02:52
I've measured the 08 Hilux, & wheelbase is 3m, so 60% of that being 1.8m beyond the rear axle allows 40cm beyond the tray's end. I'm not going to fit a carrier & motorbike in here, so I better change my focus to a single bike trailer!

Thanks to all for this discussion.
AnswerID: 486866

Reply By: garrycol - Sunday, May 27, 2012 at 13:03

Sunday, May 27, 2012 at 13:03
In that ebay listing for bike carrier it lists a pic of the type of hitch required - it actually shows a Mitch Hitch on a Range Rover Sport - is actually my pic - my car taken in my driveway - guess there is no issue but just go to show that any pic that goes up on the internet can end up anywhere.

Maybe I should ask for a cut of the sales :-)



Garry
AnswerID: 486894

Reply By: Cybermike - Sunday, May 27, 2012 at 16:25

Sunday, May 27, 2012 at 16:25
Go your hardest for a cut of the sales - good luck! I just saw a motorbike carrier on a trayback ute that was higher than hitch level, & the leading edge of the outrigger tie-down bars were ahead of the trailing edge of the tray - so really tight for the bike. Even though there was a canopy, there was a crane mounted that I guess would be used to lift the bike up. I wish I could have caught up to it to get photos! So maybe it is possible to get by without a trailer? Regards.
AnswerID: 486903

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