Tow bar vs bike rack (1 Viewer)

[Mags52]

Can anyone help me with some maths please? We have a towbar on our van and use a Thule towball bike rack that weighs about 15kg. Our bikes weigh about 10 kg each.
We are currently overweight on the rear axle by about 80 kg (but not overweight in the van in total) so we're considering having the towbar removed and putting on a Fiamma rack. I'm thinking that the additional cantilever effect with the rack extending from the towbar will make the overall weight on our rear axle even greater than the actual weight of the towbar and rack and doing this might get us better balanced.
I have no idea how to calculate the additional weight on the axle and don't want to spend a small fortune changing the set up for a relatively small benefit. We only use the towbar for the bike rack as we've tried towing a trailer and didn't like it.
Mags

 

[buttons]

Can anyone help me with some maths please? We have a towbar on our van and use a Thule towball bike rack that weighs about 15kg. Our bikes weigh about 10 kg each.
We are currently overweight on the rear axle by about 80 kg (but not overweight in the van in total) so we're considering having the towbar removed and putting on a Fiamma rack. I'm thinking that the additional cantilever effect with the rack extending from the towbar will make the overall weight on our rear axle even greater than the actual weight of the towbar and rack and doing this might get us better balanced.
I have no idea how to calculate the additional weight on the axle and don't want to spend a small fortune changing the set up for a relatively small benefit. We only use the towbar for the bike rack as we've tried towing a trailer and didn't like it.
Mags

Removing the tow ball you will still be overweight at the rear. Can you not move a few bits forward.

 

[Clickem]

When you hang something on the back it adds weight to the rear wheels and ALSO removes it from the front wheels. The effect is basically the weight multiplied by the distance, that it hangs back from the rear wheels

This is counterbalanced by the distance from the rear wheels to the front wheels

If your van was 4 metres between front and rear wheels, then 100kgs added 2 metres to rear of axle would lighten the front by 50kgs

100 X 2 = 50 X 4

The total weight added to the rear wheels would be 150kgs

Hope that makes sense

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[busby]

Can anyone help me with some maths please? We have a towbar on our van and use a Thule towball bike rack that weighs about 15kg. Our bikes weigh about 10 kg each.
We are currently overweight on the rear axle by about 80 kg (but not overweight in the van in total) so we're considering having the towbar removed and putting on a Fiamma rack. I'm thinking that the additional cantilever effect with the rack extending from the towbar will make the overall weight on our rear axle even greater than the actual weight of the towbar and rack and doing this might get us better balanced.
I have no idea how to calculate the additional weight on the axle and don't want to spend a small fortune changing the set up for a relatively small benefit. We only use the towbar for the bike rack as we've tried towing a trailer and didn't like it.
Mags

Don't get caught,,,big fine,,,BUSBY

 

[funflair]

Basically what they said above but I wasted time drawing you a picture, You need to know the dimensions of you van but the example is as follows:
50kg including the rack at 1.5m from where it theoretically turns about the back wheel =75 this automatically takes weight off the front axle 75/3 =25kg so in the example you add the original 50kg to the 25kg pinched from the front axle =75kg on the back axle.
Substitute your own figures and then also subtract the weight of the tow bat when it is removed, then add the weight of the rack and bikes back on but of course they will be slightly closer to the back axle so will transfer a litttle less weight from the front axle.
In conclusion your biggest weight saving would be in removing tow bar completely so it depends how chunky it is but doubt if you are going to see the full 80kg you require.

Sorry I dont think the drawing has made it any clearer.

Martin

 

[tonyidle]

This should clarify it:

New front axle load (new F) = F – [L x (O ÷ W)]

New rear axle load (new R) = R + L + (F – new F)

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[ludo]

Bearing in mind you have capacity in the overall payload weight, have you looked into uprating the back axle?

 

[Mags52]

We've had the whole van uprated to its maximum 3900kg but were still overweight on the back axle. We have air suspension on the back and have now pumped it up a bit but still have plenty of room to go higher. Before we upped the air in the suspension the steering was light, now it's settled down. Haven't had it weighed since we upped the air in the back but it's certainly more stable. We've also started carrying a couple of heavy things (wine e.g. ) under the front seats. We're in the Algarve at the moment so have no idea how to go about getting it weighed again.