Weight for carrying a scooter

[haganap]

I want to carry a Honda swing125 on my 3.0l Mercedes.

There's no issue with the weight in terms of payload but what about down force on the toe bar? Is 165kg

 

[peterc10]

And also what about the additional load it imposes on the rear axle - if it is on the tow bar I would guess it would add over 200kg because of the cantilever effect.

 

[haganap]

As said that's covered just want to know the downame force weigh the on the tow bar

 

[Mikeco]

What weight has the tow bar been designed for, mine is maximum 100kg, should be a sticker on it.

 

[Badknee]

Paul @haganap @Jim has done a graph somewhere with everything you need to know about it.

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[haganap]

What weight has the tow bar been designed for, mine is maximum 100kg, should be a sticker on it.

Thanks there's no sticker on it. It's on a merc 3.0L its a standard chassis fit from what I can see.

 

[haganap]

Paul @haganap @Jim has done a graph somewhere with everything you need to know about it.

No pal
I'm aware of that. Is not the info I need. I know what my chassis weight is. I know what my axle weights are... iv want to know what my tow bar capacity is

 

[peterc10]

Is your yow bar a factory fit? In that case the converter ought to be able to tell you. Or does it have any name on in the way of fitter or manufacturer? Without any idea of who designed it or who fitted it it might be a bit difficult to get a definitive answer.

 

[pappajohn]

Paul, me old mate....out of all the bikes being carried on a towbar mounted bike rack how many do you think have been checked for download.
Most won't even have been checked for axle loading.
Main consideration for nose weight is for trailers and caravans......tail wagging the dog.
bike racks don't wag, too short.
make sure all fixings are tight then just do it.

 

[haganap]

Yeah John. .I'm thinking I've got air rides on the back the weight is OK. Might just go for it for the time it's on.

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[pappajohn]

When you think car and caravan, the nose weight is set static...you load the van to keep it within limits.
How much downforce is applied to the ball when the caravan starts nodding its head and even moreso with weight transfer under heavy braking....back of car coming up, nose of caravan going down.
100kg downforce could easily become 2 or 300kg.

Im 117kg and standing on my towbar hasnt broken it yet.

 

[PhilG]

Paul, me old mate....out of all the bikes being carried on a towbar mounted bike rack how many do you think have been checked for download.
Most won't even have been checked for axle loading.
Main consideration for nose weight is for trailers and caravans......tail wagging the dog.
bike racks don't wag, too short.
make sure all fixings are tight then just do it.

This.. if there is no limit written on the bar, you cant be over it can you..

 

[MikeD]

It appears to be a very grey area as easy lifter make a bike rack that fits on a towbar that carries 200kg.
http://www.easylifter.co.uk/Non-Lift-Scooter-Rack.htm

Watling engineers make a 130kg version.
http://www.watling-towbars.co.uk/motorbike_scooter_carrier.html

Both appear to say that it would be mounted on a standard flange towbar.

 

[pappajohn]

This.. if there is no limit written on the bar, you cant be over it can you..

Yep....except, if theres no limit marked its either pre type approval or its not type approved.
The first is legal, the second isnt depending on age.

 

[PhilG]

Yep....except, if theres no limit marked its either pre type approval or its not type approved.
The first is legal, the second isnt depending on age.

I know people who have bikes on the A frames of Caravans, and on the Bar and pull a caravan too.

I seem to remember 11st being nose weight when i pulled a van, but i'm wondering at what trailer weight equates to 100kg load, which is on the plate that i just found on mine.

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[Minxy]

Maybe I'm missing the point but if you:

• know the rear axle weight and are confident that you have enough spare capacity to carry the scooter on it
• have taken into account the additional overhang distance load (which varies dependant on the overhang of the scooter and rack from the rear wheels)
• are confident that the tow ball is sufficiently secured to the existing chassis and that it and the chassis are strong enough for the job you intend

... why do you need to know what the down force is?

Surely it is the combined weight of the tow bar, rack, scooter and overhang loading that is important rather than down force?

If your MH is the one in your avatar, which appears to be an Autosleeper, then I doubt if you'd have sufficient capacity on the rear axle for the above!

 

[Geo]

He wants to know how much down force can be applied safely ie before the bolts or the ball snaps off
Its the vehicle that has maximum downforce figures, not the tow bar per say, so all will be rated differently depnding on rear chasiss construction
As stated above some experts have settled on an average of 200kg for their hydraulic rack that rely entirely on the ball mounting bolts and have been fitted to every type of MoHo i can think of

 

[haganap]

Maybe I'm missing the point but if you:

• know the rear axle weight and are confident that you have enough spare capacity to carry the scooter on it
• have taken into account the additional overhang distance load (which varies dependant on the overhang of the scooter and rack from the rear wheels)
• are confident that the tow ball is sufficiently secured to the existing chassis and that it and the chassis are strong enough for the job you intend

... why do you need to know what the down force is?

Surely it is the combined weight of the tow bar, rack, scooter and overhang loading that is important rather than down force?

If your MH is the one in your avatar, which appears to be an Autosleeper, then I doubt if you'd have sufficient capacity on the rear axle for the above!

No that motorhome in the avatar is brand new at the time. The children are mine and their cousins...One of mine is a serving soldier and the others are all at uni so taken a while ago.

As said earlier the vechile is a 3.0l Mercedes..

He wants to know how much down force can be applied safely ie before the bolts or the ball snaps off
Its the vehicle that has maximum downforce figures, not the tow bar per say, so all will be rated differently depnding on rear chasiss construction
As stated above some experts have settled on an average of 200kg for their hydraulic rack that rely entirely on the ball mounting bolts and have been fitted to every type of MoHo i can think of

Absolutely...
200kg seems to be banded about but im not so sure..some experts is the bit that concerns me...some experts said the titanic wouldn't sink...
The toe bar is factory fitted so I thought someone wound have the difinitive Merecedes expert opinion.

 

[Geo]

Your opinion on "Experts" is noted
hadn't realised you wanted flavour of the month figures

 

[haganap]

Your opinion on "Experts" is noted
hadn't realised you wanted flavour of the month figures

Eeither of those would do. . or has anyone seen a scooter attached to a to ball in the middle lane of the M6 would do

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[Landy lover]

One of the most important things to take into account would be the cantilever effect on the rear axle causing light steering and possible aquaplaning on a wet road. A nose weight exerted by a trailer which as PJ says could be 200kg + when going over bumps would not be a constant force. The bike on the back would be a constant force so the cantilever effect would be constant. Air rides would only stop the rear springs compressing too much not reduce the cantilever effect.

 

[Wagoneer]

Any competent structural engineer or tow bar fabricator should be able to check your setup and give advice about your proposed vertical loading and twisting forces caused by the offset load on the tow bar. They will then add a factor of safety of 2 or 3 to account for the indeterminate dynamic loading whilst the vehicle is in motion.

It's all about weld sizes/lengths, metal thicknesses/metal type and bolt sizes/high tensile etc.

I met a guy in Spain who carried a 100kg scooter on a tow bar and the tow ball bolts gave way. Mind you, the vehicle overhang was at least 3 metres so probably failed from repetative dynamic loading.

 

[Minxy]

No that motorhome in the avatar is brand new at the time. The children are mine and their cousins...One of mine is a serving soldier and the others are all at uni so taken a while ago.

As said earlier the vechile is a 3.0l Mercedes.

Having never owned an Autosleeper MH I wouldn't know what they are based on so could have been a Merc and it could easily have been your current MH as you don't mention what you have, so are we talking about a standard van with a long wheel base etc, or a coachbuilt, or something else? What it is will effect forumites' answers but to be honest the only people who will be able to tell you are either Mercedes themselves (assuming it's a van) or an engineer who can check it out in the flesh, with not knowing what vehicle we are talking about it is pure speculation on our part.

 

[TheDogMan]

I am no expert on any of this I put my bike in a trailer, BUT, would it not be easier if the age, make & model of MoHo had been supplied in the first place ??

 

[FJmike]

Our first motorhome had a towbar and rack fitted by the dealer. We had a Yamaha 125 two stroke probably 110k at most. When we took the van down the road it was the most frightening thing I have ever experienced, absolutely no steering control and very little in the way of brakes. Afterwards I found out that for every 12 inches past the back axle you double the weight of the bike to get the loading (axle I assume)

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[PhilG]

Any competent structural engineer or tow bar fabricator should be able to check your setup and give advice about your proposed vertical loading and twisting forces caused by the offset load on the tow bar. They will then add a factor of safety of 2 or 3 to account for the indeterminate dynamic loading whilst the vehicle is in motion.

It's all about weld sizes/lengths, metal thicknesses/metal type and bolt sizes/high tensile etc.

I met a guy in Spain who carried a 100kg scooter on a tow bar and the tow ball bolts gave way. Mind you, the vehicle overhang was at least 3 metres so probably failed from repetative dynamic loading.

You wont ever break 10.9 or 12.9 bolts, with a scooter .

 

[haganap]

Our first motorhome had a towbar and rack fitted by the dealer. We had a Yamaha 125 two stroke probably 110k at most. When we took the van down the road it was the most frightening thing I have ever experienced, absolutely no steering control and very little in the way of brakes. Afterwards I found out that for every 12 inches past the back axle you double the weight of the bike to get the loading (axle I assume)

I already have a scooter on a rack and roll trailer..
It's light weight Honda vision 110cc on a rack and roll scooter rack. I don't have the problems you mention it sits on there and I have no idea its there.
I was interested in upgrading to the bike mentioned without having to refabricate a new scooter rack by someone like Mick Parkinson.


The mention of what vechile I owned would make no difference..it's a Mercedes 3.0l as stated. I'm more interested as @Geo worked out and @Wagoneer commented on...
It's about the downforce on the tow ball and any potential twisting of the chasis or breaking of towball bolts..taking any over hang out of the equation which would increase any potential for breakage the make and model of van again would be pointless unless I srated the actual dimensions of the fabrication coupled with the quality age and stress report of the actual welds carried out. .

I think I've concluded that should I bother to upgrade I will go for a transverse trailer although it would appear 2 experts have differing views on both legality and practicality of said item..

 

[Minxy]

... in which case if you're not willing to give full info of what the base vehicle is other than the engine size and manufacture how do you expect to get appropriate/specific answers? ... I did mention the chassis build etc in my earlier post #16 ....

 

[Chris51]

I carry a Honda Innova 125 on the towbar (witter 100 kg load ) and rack of my PVC,Bike is 100kg-rack 20kg and allowing for o/hang means about 175 kg on rear and - 50kg off front.(using mentioned graph).The towbar rack is upgraded by a 50x6mm arm each side bolted to rack and to chassis of van.I have tested on road and cant hardly tell it is on back at 60mph (which is my max cruising speed .)The rack is bolted on towbar by 4x19mm bolts.Still plenty of r/axle-van load left.Wouldnt like to carry any heavier bike on back which is why I got Innova .

 

[haganap]

I carry a Honda Innova 125 on the towbar (witter 100 kg load ) and rack of my PVC,Bike is 100kg-rack 20kg and allowing for o/hang means about 175 kg on rear and - 50kg off front.(using mentioned graph).The towbar rack is upgraded by a 50x6mm arm each side bolted to rack and to chassis of van.I have tested on road and cant hardly tell it is on back at 60mph (which is my max cruising speed .)The rack is bolted on towbar by 4x19mm bolts.Still plenty of r/axle-van load left.Wouldnt like to carry any heavier bike on back which is why I got Innova .

Sounds like a very similar set up to my own..
Having had a further look through I think the option of getting the silverwing would be best explored with a transverse trailer or sticking with what I have.

It's just if I need to get something for a trailer I might as well get a real bike which negates the need for a scooter.

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