Working Out Ball Weights

[baz1]

Hi Guys,

We have just bought a SWAG SCT16 Hybrid (we are waiting for it to be delivered). We are looking at bike rack solutions, we could probably fit two bikes on a rack attached to the rear van wall, and two on the drawbar, but I would like to try and predict how the weights will impact ball weight, so I can keep the ball weight at 10%.

I have taken the following measurements:

Hitch to rear bumper
Axle to hitch
Axle to place where bikes would be located on front A-Frame
Place on front drawbar where bikes would be situated to front hitch

Can anyone point me to a program, or app, which would work out how the theoretical weights of the bikes, on the front A-Frame, and rear wall, would impact the ball weight?

Thanks!

[#jonesy]

2 bikes either end will just cancel each other out.

[GeoffA]

2 bikes either end will just cancel each other out.

...only if they are equi-distant from the axle.

[KeithB]

It might be best to start with a weighbridge ticket when you pick up the camper. All buyers should insist on that. Then maybe buy a cheap tow ball scale from Repco or Supercheap and have a fiddle with the loaded and unloaded weights. That way you will know for sure.
Keith

[Foo]

For about $20, you can go to a public weigh bridge and find out your ball weight and combined tare weight in 5mins. 

Foo

[GeoffA]

baz1,

To work out the difference in ball weight due to the bikes:

Reaction R = [(A x C) - (B x D)] / Z

Where:
R = Reaction at the ball (kg)
A = Weight of bikes + front rack (kg)
B = Weight of bikes + rear rack (kg)
C = Distance of A from van axle (m)
D = Distance of B from van axle (m)
Z = Distance of R from van axle (m)

 

[baz1]

Hi Mate,

Many thanks for your info, unfortunately, being of limited mathematical abilities, calculating that equation is well beyond my abilities! I have been scouring the net high and low for a calculator when I can just input the figures, and it gives you an awnser, but I can’t find one.

You are obviously a bit of a ‘jet’ on this front, would you be able to provide the answers for the adjusted ball weights for points 1-6? Any help would be appreciated!

Weights based on average weight Mountain Bike being 12kg
Plus weight of Gripsport = 30Kg for van rack and bolt on mount
So total of 12kg per bike, plus 30kg for the bike rack
Based on laden ball weight being 225kg PRIOR to any bikes being added
So new ball weight would include existing ball weight of 225kg

1.   Adding two bikes to A-Frame (+54kg) no bikes to rear bumper, ball weight changes from 225kg to approx :
2.   Adding two bikes to A-Frame (+54kg), two bikes to rear bumper (+54kg), ball weight changes from 225kg to approx :
3.   Adding two bikes to A-Frame (+54kg), one bike to rear bumper (+34kg), ball weight changes from 225kg to approx :
4.   Adding two bikes to rear bumper (+54kg), nil to A-Frame, ball weight changes from 225kg to approx :
5.   Adding two bikes to rear bumper (+54kg, one to A-Frame (+34kg), ball weight changes from 225kg to approx :
6.   Adding two bikes to rear (+54kg, nil bikes to A-Frame, ball weight changes from 225kg to approx :

baz1,

To work out the difference in ball weight due to the bikes:

Reaction R = [(A x C) - (B x D)] / Z

Where:
R = Reaction at the ball (kg)
A = Weight of bikes + front rack (kg)
B = Weight of bikes + rear rack (kg)
C = Distance of A from van axle (m)
D = Distance of B from van axle (m)
Z = Distance of R from van axle (m)

 

[GeoffA]

Hi baz1,

Happy to help, but need the measurements you mentioned in your original post.

 

[baz1]

Thanks mate, sorry forgot the measurements!

- [ ] Total length of van 670cm
- [ ] Distance hitch to axle - 450cm
- [ ] Distance axle to rear bumper - 250cm
- [ ] Distance point on drawbar where bikes will be located to front hitch - 110cm
- [ ] Distance point on drawbar where bikes will be located to axle - 340cm
- [ ] Distance point from point on rear bumper where bikes would be situated, to axle - 250cm

[GeoffA]

Here ya go baz1....

Weights based on average weight Mountain Bike being 12kg
Plus weight of Gripsport = 30Kg for van rack and bolt on mount
So total of 12kg per bike, plus 30kg for the bike rack
Based on laden ball weight being 225kg PRIOR to any bikes being added
So new ball weight would include existing ball weight of 225kg

1.   Adding two bikes to A-Frame (+54kg) no bikes to rear bumper, ball weight changes from 225kg to approx : 225kg + 41kg = 266kg
2.   Adding two bikes to A-Frame (+54kg), two bikes to rear bumper (+54kg), ball weight changes from 225kg to approx : 225kg + 11kg = 236kg
3.   Adding two bikes to A-Frame (+54kg), one bike to rear bumper (+42kg), ball weight changes from 225kg to approx : 225kg + 18kg = 243kg
4.   Adding two bikes to rear bumper (+54kg), nil to A-Frame, ball weight changes from 225kg to approx : 225kg - 30kg = 195kg
5.   Adding two bikes to rear bumper (+54kg, one to A-Frame (+42kg), ball weight changes from 225kg to approx : 225kg + 2kg = 227kg
6.   Adding two bikes to rear (+54kg, nil bikes to A-Frame, ball weight changes from 225kg to approx : Same as scenario 4

 

[baz1]

Thanks so much mate, that’s much appreciated!

Here ya go baz1....

 

[GeoffA]

Thanks so much mate, that’s much appreciated!

No problem baz1.

All numbers are based on the assumed ball weight of 225kg.

Don't forget to factor the extra weight of the bikes and racks into your total weight.
The previous suggestions from Keith and Foo to visit a weighbridge are very valid.
It's the best way to understand what's really going on....

 

[Bird]

All numbers are based on the assumed ball weight of 225kg.

OUCH!

[baz1]

Thanks mate, again much appreciated 👍

The unladen ball weight is 150kg, users report 220kg when the van is fully loaded, so a starting point of 225kg is probably reasonable. I predict the van, fully loaded will weight about 2550kg, so for the ball weight to come in at 10%, I want it around 260kg. Most of the time, we would be traveling with three bikes, so based on the weights you have provided, we would probably stick two on the A-Frame, and one on the back wall, which brings us to 243kg, which is about right, we can always add a little more if required 👍

No problem baz1.

All numbers are based on the assumed ball weight of 225kg.

Don't forget to factor the extra weight of the bikes and racks into your total weight.
The previous suggestions from Keith and Foo to visit a weighbridge are very valid.
It's the best way to understand what's really going on....

 

[Frawls]

Hi Hope you worked out your ball weight, although I am more interested in your opinion  of your new SWAG SCT16 Hybrid. When you get it, would luv to hear your thoughts. Going to check one out this Saturday.

[baz1]

Hi Mate,

We have ordered the STC16 full roof version, it was a bit of a toss up between the full roof and pop top. I’ve had a good look over them three times now. The quality seems pretty good, I like that there is no pop out bed, and the layout works well. I like that the bunks don’t dominate the van, so when the kids take off, you won’t have a huge waste of space. The weights are also a huge bonus over many of the other Chinese imports, ball weight at 150kg, TARE 2100kg. I’ve seen 15ft hybrids with unladen ball weights of 250kg, and TARE’s of 2400kg 😳 The other thing is, and I never actually thought of this until after we ordered, you can put two bikes on the front, which you can’t do on many of the other Chinese imports, as the ball wet is already through the roof, and you can put two on the rear, which you can’t on many other models because they have two spare tyres there.

In the end we went for the full roof, as most people seem to make that transition sooner or later, so might as well do it now, and save some money in the long run. You also get more storage, and I think the insulation properties will be better. That being said, I like the lower towing profile of the pop top, and it feels a bit more like you are camping when your inside.

Not sure when we will get it delivered, we were quoted 4-6 months, but there are people who ordered at the beginning of the year, who are just getting theirs now! But then I saw on the SWAG FB page, they are guaranteeing delivery of some of their camper trailers by April next year 🤷 So I have no idea what’s going on.

Are you a member of the SWAG FB page? There are two, one run by SWAG, so potentially it could be argued, not administered in an entirely impartial manner (though I have no personal experience of this), and another one which is not, where some people appear to go to complain!

What are you looking at ordering? (Pop top or full roof). If have lots of photos, if you find me on FB Messenger (Robert SOPER, I’m the one in the photo with the wife and two kids), I can send them to you 👍

[McGirr]

Unfortunately until you get the hybrid you can only go on estimates. The hybrid ( empty ) may have a higher ball weight or even a tad lower.  Then its how.much gear you decide to add to the hybrid and where it's placed.

I would suggest once receiving the hybrid, add what you would take with you then get it weighed and work from there. You may have to reposition a few things to get the weight and ball weight how you like it. Then consider the bike racks.

Mark

[Bird]

Police reveal results from caravan-weighing ‘education event

Here’s what police discovered in the various categories tested:

VEHICLE LOADING AS A PERCENTAGE OF GVM:
Overweight: 16
90-99 per cent: 20
80-89 per cent: 8

TRAILER LOADING AS A PERCENTAGE OF ATM:
Overweight: 17
90-99%: 19
80-89%: 7
<79%: 1

TRAILER LOADING AS A PERCENTAGE OF THE GTM:
Overweight: 6
90-99%: 19
80-89%: 15
<79%: 3
* 1 van had no listed GTM

OVERALL COMBINATION STATUS OF GCM:
Overweight: 8 (18% of all weighed combinations), with the highest overweight reading being 699kg).
90-99%: 19 (43% of all weighed combinations. 9 of these 16 were between 96% and 99% of their listed GCM).
80-89%: 9 (20% of all weighed combinations).
<79%: 8 (19% of all weighed combinations).



Those caught exceeding weight limits while towing caravans in Queensland can expect fines of up to $287 and three demerit points, $469 and three demerit points in NSW, $238 to $1580 in Victoria, up to $591 in South Australia and $130 to $735 in Tasmania.

https://bigrigs.com.au/2023/12/12/police-reveal-results-from-caravan-weighing-education-event/

[warrenm]

Those numbers don't surprise me, unfortunately. We got stuck behind a vehicle loaded like the one in your post a October on the Newell Hwy, as soon as they went over 80km/h, it would start wagging it's tail, brake lights would come on, couldn't wait to get past so we didn't have to see the accident that was waiting to happen. 

[Fizzie]

results from caravan-weighing ‘education event

Sure, some of them are bad, but I would have said that loaded at 80-90% was OK

brake lights would come on

Wonder if that may have been ESC operating?

We've got it on the new van & it activated a couple of times coming home last week, usually due to hitting a bump (of which there were lots! ) on a curve in the road. You well & truly know about it when it happens! Driving along normally, then all of a sudden the van brakes lock on, then off again, 3-4 times! "What the ..."!!!

[DandyD]

I always recommend this video on the (rare) occasions people ask me for advice about loading trailers.

7 trailer weight scenarios compared

https://m.youtube.com/watch?v=JeEEC5eVNCk