Is it really safe to carry 4 bikes on a towbar carrier?

[cailean]

Hi all, I have a Forester with a OEM towbar installed. The owner's manual states that the 'maximum permissible static vertical' load is 80kg. So I assume the nose weight (in UK) or tongue weight (in US).

Ok, I have installed a Thule EuroClassic G6 929 4 bike carrier (well 3 bike carrier plus an adapter for a 4th) and tested the 4 bikes on it. 2 adult bikes - a 650b MTB, a 26" hybrid, a 24" kids bike and a 20" kids bike. The total weight of the carrier, the 4th bike adapter and the 4 bikes is about 72kg, if my old scales are accurate...

Now bearing in mind that xxx lbs of weight a foot or more back from the trailer ball position has much more effective downforce than weight on a trailer ball a few inches back from the rear of the hitch.

I have to say I find the 4 bikes on it does seem to be too much and sticks out too far in the back. I do have 2 bike racks on the roof so could put 2 on the roof and 2 on the rear rack but I always found that the bikes on the roof seemed more unstable. We used to put the 2 adult bikes on the roof and the kiddies bikes in the boot but now that the little ones bike are bigger due to children that keep growing they can't go in the boot hence the idea for the rear bike carrier to hold all 4. I was hoping to not use the roof ones and just have all 4 at the rear. The pictures attached shows the 4 on it.

So I would appreciate any thoughts on do I just put the 4 on the rear and stop being silly and paranoid or do I play safer and put one or two on the roof and the others the rear carrier?

I will be driving 300 miles to Wales for half term and then around Snowdonia with the bikes.
Cheers.

Edited by cailean on Saturday 7th February 20:04

[cailean]

[jodypress]

Could you not use some bungee cords and wrap them round the top bars on the last bike and through the roof rack at the back to support the weight?

[Justin S]

I have a 4 bike carrier on my towball and have taken it 1000 miles up north and back on a holiday, but suspect the bikes to be lighter than yours, but carrier is an old steel Thule thing, which pulls my back sticking it on. We all survived, bikes got ridden, towball undamaged and towball weight is a weird thing, as I am sure the exertion from towing a caravan would be far more excessive than anything a bike and carrier can put on the nose weight of the ball.

[IroningMan]

I think nose weight restrictions have more to do with the overall weight distribution and its effect on handling than they do with the engineering limitations of the towing hardware.

My Discovery has a perfectly ordinary towball but a nose weight limit of 150kg.

[cailean]

Yep, I think it is more to do with the stability of the front wheels, steering, braking, cornering etc. Vertical weight concerns are different to the towing capacity of what you are pulling, hence why I am concerned. I did take it for a short test drive with the 4 bikes on it and no one else in the car and it didn't drive/feel strange but I only got up to 30 mph or so. Mind you in the 'real' world I would have the family in the car if I had the bikes loaded up too.

Edited by cailean on Saturday 7th February 22:20

[IroningMan]

Behind the wheel I found it impossible to tell that this was fitted - all-up weight was close to three tons, mind you, and self-levelling makes a difference.

[Some Gump]

OP,

That towball has to be able to handle near 2 tonnes of caravan / trailer / whatever.

I suspect that the only way to make it break with 75kg on a 4 foot lever s to drive into a wall fast enough to generate 40 odd G. If you do that, the bikes are really not the thing you need to be worrying about =)

[Tiddy1]

We have driven 1000s of miles about the country with 4 bikes on the back in all weathers including heavy snow and had no issues, you can also get similar racks to hold motocross bikes and they are not exactly light

Si

[S6OOH]

Used a heavy old 4 bike bike carrier on a variety of cars and huge distances. No problems

[paulrockliffe]

If the nose weight is 80kg and that setup is 75kg you must be over the limit because the leverage of the weight as it moves away from the towball will increase the force that's being applied.

To work it out exactly you need to take account of the horizontal distance from towball to the centre of gravity of the rack and bikes, but with the numbers you've quoted, there's no way you're not over the limit.

Whether it's enough to cause a problem is one thing, but it's worth bearing in mind that there could be issues if you were involved in an accident, or just if the police were out doing spot checks as you drive past.

[cailean]

Oh bother...that's what I was thinking...guess the 24" bike could go on the roof rack and not use the adapter. That would bring the weight down to about 58kgs.

Curious to get a formula to calculate it properly

[numtumfutunch]

cailean said:

Oh bother...that's what I was thinking...guess the 24" bike could go on the roof rack and not use the adapter. That would bring the weight down to about 58kgs.

Curious to get a formula to calculate it properly

I bought a previous version of this rack 6 years ago and went through the same thought process as you

The scientific answer still evades me but over the years its been to the South of France, Alps and around the UK with up to 4 MTB's attached to it without issue

Cheers

[Some Gump]

paulrockliffe said:

If the nose weight is 80kg and that setup is 75kg you must be over the limit because the leverage of the weight as it moves away from the towball will increase the force that's being applied.

To work it out exactly you need to take account of the horizontal distance from towball to the centre of gravity of the rack and bikes, but with the numbers you've quoted, there's no way you're not over the limit.

Whether it's enough to cause a problem is one thing, but it's worth bearing in mind that there could be issues if you were involved in an accident, or just if the police were out doing spot checks as you drive past.

I disagree.

He nise weight on a towball is not the same as the turning moment on the towball assembly. The mass attached to the towball is still 75kgs.

[cailean]

numtumfutunch said:

I bought a previous version of this rack 6 years ago and went through the same thought process as you

The scientific answer still evades me but over the years its been to the South of France, Alps and around the UK with up to 4 MTB's attached to it without issue

Cheers

Thanks, what kind of vehicle was it used with?
Ta

[scubadude]

Tow ball bike racks are the motoring equivalent of appearing on Jeremy Kyle IMO.

Only once have I every worried for my life, once in the outside lane of the M4 when 3 bikes on a rack fell off the tow ball of a 4X4 and landed in front me, Both car and bikes written off.

I also had a hire car ruined when a herbet with bikes on the back tried to squeeze past and "forgot" about the wheel sticking 8" out each side and dragged the paint off every panel down one side....

Is it safe- No.
Man up and put them on the roof, yes you will feel the weight so drive slower- which you should do anyway if you hung them on the back

IMO the rack on the tow ball is too vulnerable, not secure enough and even if you put repeater boards on they are rarely as good as your primary lights. Frankly I'd buy a trailer before considering a ball rack.

[vwsurfbum]

I use a 3 rack on the back of my Touareg, the tow bar mounted racks has made it so much safer than on the roof. I had my carbon HT on the roof of my old Leon FR550 when it came off over a sharp speed bump causing damage to my roof and devaluing it massively. I have done trips all over the UK with 3 big rigs, all our gear and 3 big blokes inside, best way of transporting bikes FACT.

[cailean]

Any engineers in the house who know a formula to calculate the vertical load when the load is not all vertical?

For the long run to Wales I will put the 20" bike in the boot (after taking off the front wheel and pedals so it is flatter) and for short runs I will put the 24" bike up on the roof. That way I will just have 3 bikes on the rear rack and not use the extension adapter as I do feel that 4 is too much for the Forester. Looks ok for a Disco or a Touareg but that has almost twice the nose weight rating of the Forester (at least the Disco is 150 compared to 80kg for the Forester - not sure of the Touareg rating but it is a full sized SUV). The new model Forester is much higher than the old ones so getting 4 bikes on the roof is not feasible.

I have to say the Thule rear rack is very well built and the bikes feel very secure on it, more so than the roof rack (Thule 591). Curious to know how bikes fall off them on the post above, surely just not mounted properly or a rubbish rack?

Ta
C

Edited by cailean on Monday 9th February 21:31

[samj2014]

scubadude said:

Tow ball bike racks are the motoring equivalent of appearing on Jeremy Kyle IMO.

Only once have I every worried for my life, once in the outside lane of the M4 when 3 bikes on a rack fell off the tow ball of a 4X4 and landed in front me, Both car and bikes written off.

I also had a hire car ruined when a herbet with bikes on the back tried to squeeze past and "forgot" about the wheel sticking 8" out each side and dragged the paint off every panel down one side....

Is it safe- No.
Man up and put them on the roof, yes you will feel the weight so drive slower- which you should do anyway if you hung them on the back

IMO the rack on the tow ball is too vulnerable, not secure enough and even if you put repeater boards on they are rarely as good as your primary lights. Frankly I'd buy a trailer before considering a ball rack.

Both roof racks and tow bar racks have their pros and cons.
Easy enough to forget you've got them on the roof and drive under a height restriction barrier. Also if you're (as in the general 'you', not you personally) the kind of numpty to fit the bikes incorrectly to a tow bar mount rack in such a way that they're likely to fall off, I'd say chances are equally that they're going to be fitted to a roof mount one wrong as well.

If the bikes are under the max. nose weight for the car/tow bar/carrier, then there's no issue. Plenty of people do it, should be fine.

A friend of mine had a tow bar mounted rack, and carried multiple bikes all the time, on his shonky old skoda felicia with a shonky old rack. Would often carry four light-ish XC bikes, but would draw the line at 2/3 downhill bikes. Only once did anything go wrong - his bike ended up being dragged half a mile down the road with the handlebars on the road because he forgot to fasten it properly due to being tired after riding (ended up taking about two inches off his handle bars, ended up ruining a grip, brake lever and bars IIRC). Could've happened with a roof mount too.

If the steering feels light, slow down, same as you would with a trailer, caravan etc. Simples.

[walm]

Some Gump said:

That towball has to be able to handle near 2 tonnes of caravan / trailer / whatever.

Yes - 2 tonnes - close to evenly balanced about its own axle.
It's not 2 tonnes suspended in the air supported by the towball!!!