[Closed] Rear tow ball rack

Not those exact models but the Buzzrack I had was very well made and easy to use, unfortunately I had to send it back as the tilt function didn't allow the boot to open on my Smax

Thread hijack...

Do these clamp round the ball part?

Don't they slip and rotate?

Thread hijack...

Do these clamp round the ball part?

Don't they slip and rotate?

Not in the slightest - much to the puzzlement of some engineers that I know.

Yeh I cant get my head around how the weight of 4 bikes going over bumps waggling on the back of the car doesnt gradually cause it to slip.

Its actually stopped me buying one...

The only time I made my Strada rack move around the ball was when I reversed it into a tree. I had to take it off to put it straight again.

I can stand on my Thule rack and bounce up and down with my 14st of [s]lard[/s] muscle, and it doesn't move at all - just car suspension bounces...

The reason why they don't rotate and slip is because they're clamped on chuffing tight. The clamps are shaped so there is a large area of contact between the clamp and the ball. Bikes are actually very light. 4 bikes plus the rack is 80kg's or so? that is not very heavy in the grand scheme of things.

Buzzracks are good - well made but heavy so be wary of your nose weight.

While I do get the logic, it's still mental. It looks like a complete liability and that it should fall at any moment

I have an Atera Strada Evo, when it's tilted it looks even more mental!

My job has me driving thousands of miles each year with up to four bikes on a towball-mounted bike rack. It still doesn't quite sit comfortably with me 🙂

I've just bought a Bosal Tourer rack for my own use. Only two bikes but it folds up very neatly for storage and I reckoned it would spend more time in the garage than in use.

Have been very happy with my buzzrack.

From the Scorpion rack website the comment "[b]Made in the Surrey Hills, the heart of UK mountain biking[/b]" would put me off a bit 😯

Natrix wobbliscot. What model Buzzrack you got?

I got the Quattro 4 bike rack. Though the quality isn't as good as Thule/Atera, though depends how you define quality, it's very well. Holy and more robust and has some design feature that I think is a far superior design than the more expensive 'go to' racks. The downside is its chuffing heavy-20 kg, so load up with some heavy MTB's and you've got to be wary of your cars weight limit.

I think he amazement of how these things work is we can't really put into context the clamping forces and the resulting friction. Metal on metal surfaces actually provide quite a lot of friction. Don't forget you can friction weld, and wherever we have a machine with sliding metal contact we need to lubricate. Also look at a train, thousands of tons of train on a metal to metal contact patch probably no bigger than the contact patch of your car tyres. But the force pushing down on that contact patch area is very concentrated and therefore creates a lot of friction. The result is they've train wheels grip the rails pretty well - enough to transfer hundreds of horsepower and haul the train up hills. Same thing is going on with the tow bar rack.

I've just bought a Thule 9503 & it looks well made - trying it on Sunday.

I have the buzzrack, cant fault it for the price, oh except for the fact the tilt is next to useless. But I don't need to get into the boot so no problem.

4 bikes is really pushing it on a towball. In fact the germans have rules against that many (TUV). The problem is the ball fatiguing off. If you need to carry that many please take care to add a safety cable into the safety hole of the towbar and through your frames. One death already in the UK from bike falling off. YOU are responsible for a safe load.
Alternatively you could get a flange towbar fixed bike rack.
[url= https://auxtail.com/products/flange-fitting/ ]Flange Towbar Fix[/url]
Also if you clamp on the towball, the paint soon falls off and then it is cr@p for towing, as it gets rusty.

Has anyone used a Maxxraxx rack?

Thinking about one as we have a flange (oo-er) tow bar on our new car.

We've got a Witter ZX503 which is easy to put on, and seems very stable.
and I managed to get a foam rubber red striped warning board in Decathlon last Friday which is less damaging than the metal one I've been using up till now.

I've got an older Quattro 4 bike rack, doesn't tilt but is a bit lighter. Folds flat for storage. 2 Adult bikes & 2 childrens bikes, keeps the weight down.

Shameless opportunist advert. Ahem....

http://singletrackmag.com/forum/topic/aiston-bike-rack-3-bike-reduced-2

4 bikes is really pushing it on a towball. In fact the germans have rules against that many (TUV). The problem is the ball fatiguing off. If you need to carry that many please take care to add a safety cable into the safety hole of the towbar and through your frames. One death already in the UK from bike falling off. YOU are responsible for a safe load.
Alternatively you could get a flange towbar fixed bike rack.
[url= https://auxtail.com/products/flange-fitting/ ]Flange Towbar Fix[/url]
Also if you clamp on the towball, the paint soon falls off and then it gets rusty, and becomes poor for towing.

Don't they slip and rotate?

I thought the TUV test for 4 bikes only reccomended that an additional stabiliser should be used to prevent the rack from rotating.

Why if I can tow a trailer with 2 horses in ( prob 2500kg) on my tow bar do 4 bikes cause a problem?

Obv the trailer has axles and is braked but I can't see how 40kg of bikes creates more of a moment than a small per cent of 2500kg?

4 bikes doesn't cause a problem, unless the entire assembly exceeds the noseweight. Though I did notice that skoda include a chart for bike carrier weights in our kodiaq's manual: the bottom line of which suggests I should never, ever, tilt the carrier.
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4 bikes is more like 60kg (15kg each), plus maybe 20kg for a 4 bike rack. That's a good point about tilting - max noseweight is based on vertically down at the ball. I have a 2 bike Buzzrack, bought from a member here, very good, but wouldn't want to have a 4 bike version.

Apologies for the pedantry interlude but...
Road bike 1 6.5kg
Road bike 2 8kg
FS 12.5kg
Hardtail 11kg

38kg and I only needed to sell a kidney for road bike 1

I can see that 4 enduro bikes will be 50-60kg but I'm still not sure why it creates a problem for something that can tow up to 3.5 metric tonnes?

Also if you clamp on the towball, the paint soon falls off and then it gets rusty, and becomes poor for towing.

Whut? In my many years of towing, I've never seen a painted towball, a dab of grease for low rotation, high force and that's it.

Jakester
I've used a maxxraxx 4 bike rack for years on a flange tow bar, in fact just changed the fitting tonight as now it's on a defender with a rear spare tyre. Rack is really secure, but you need to pad/cover the bike holders to prevent scratches. I also use Bungy cables on the handlebars and back to front the bikes. Never used the steady straps before, will on the new one as it's more "out back". Great system, hence I replaced the upright to fit new care rather than getting a different one!

[quote=joat ]

Also if you clamp on the towball, the paint soon falls off and then it gets rusty, and becomes poor for towing.

dickyhepburn - Member
Jakester
I've used a maxxraxx 4 bike rack for years on a flange tow bar, in fact just changed the fitting tonight as now it's on a defender with a rear spare tyre. Rack is really secure, but you need to pad/cover the bike holders to prevent scratches. I also use Bungy cables on the handlebars and back to front the bikes. Never used the steady straps before, will on the new one as it's more "out back". Great system, hence I replaced the upright to fit new care rather than getting a different one!

Great, thanks.

I can see that 4 enduro bikes will be 50-60kg but I'm still not sure why it creates a problem for something that can tow up to 3.5 metric tonnes?

Because it's not the gross weight you should be concerned with (a bike rack would come under the cars MGW not the car+trailer MGW). It's the nose weight. A 3.5t trailer can still only have a nose weight of 75kg (or whatever your car will allow).

A bike rack weighing 75kg and sitting directly above the towball would be fine, but impossible. If the load is (in that Skoda example) 60cm back form the towball then it's acting on a long lever and the maximum load is reduced to 35kg.

IF you exceed that maximum load you're effectively unweighing the car's front wheels and overloading the rear axle. Leading to reduced braking, the car understeering, or a fine if the police are feeling overzealous (they do occasionally have crackdowns in popular areas like the Peak).

The problem is magnified the smaller the car. In a big estate the towball is already a long way back from the rear axle so a longer lever makes less difference and it will have bigger nose load limits to start with (75kg is high for a car). Something Fabia/Fiesta/Polo sized on the other hand will have the axle further to the back of the car so adding distance has proportionally more effect, and the nose weight is likely to be lower (35-50kg or so).

4 bikes on the back of a 4x4 is fine.
4 bikes on the back of a Fiesta is probably dangerous even if it comes under the nose limit for the tow ball.

Also if you clamp on the towball, the paint soon falls off and then it gets rusty, and becomes poor for towing.

Whut? In my many years of towing, I've never seen a painted towball, a dab of grease for low rotation, high force and that's it.

My caravan has an Alko hitch with friction plates in to stabilize the van and requires the ball to be spotlessly clean of grease and paint for it to work correctly.

4 bikes on the back of a Fiesta is probably dangerous even if it comes under the nose limit for the tow ball.

Just put some paving slabs in the front passenger foot well to balance it all out 😀

Just put some paving slabs in the front passenger foot well to balance it all out

You may be jesting but, I drive a flat bed mounted cherrypicker at work, to take weight off the front it has four paving slabs mounted behind the back axle.

Thank you thisisnotaspoon

I've just looked up the towball limit for the Disco Sport and its 100kg so I can see why I haven't noticed the front feeling light with 14-20kg of bikes on

4 bikes on the back of a Fiesta is probably dangerous even if it comes under the nose limit for the tow ball.

It interests me as surely the forces applied by a caravan being towed will be greater than the forces applied by the static bike rack

Any physicists able to say either way ?

It interests me as surely the forces applied by a caravan being towed will be greater than the forces applied by the static bike rack

The bike rack will actually affect the car more. Say you put 50kg 2m behind the rear axle on a bike rack and bounce it up and down to produce an acceleration of 10m/s2 (extra to gravity) you would get a peak moment of (50x9.81 + 50x10) x 2 = 2000Nm

A caravan with a nose weight of 50kg 1m behind the axle would be 1000Nm in the same scenario. If it was a 750kg caravan then the other 700kg is on the axle. It will push forwards and back under braking or acceleration but wont affect it up and down. The same applies to side loads, throw a caravan round a corner and 700kg is on the axle, only 50kg aplies a side load to the towball. Wheread a bike rack is swinging around on a big lever.

Or to put it in practical terms, my car feels much diffrrent with a bike rack than it does towing my boat.

A friend of mine once laced 4 bikes on a three bike tow bar with only a 50kg weight limit [ peugeot 206] and found that it drove perfectly fine on the hills and mountains of the Lakes

Id believe you, except its a 206, so would be understeering everywhere normaly without the rack (untill you lifted off and went into the ditch backwards). So maybe there wouldnt be a difference to notice :p

Any physicists able to say either way ?

cheers all

the friend was surprised by how little it affected the handling...perhas for the reasons you note.

Tinas: you forgot the moment around the rear axle from the drawbar thrust which will have a lifting effect on the front wheels under acceleration

except its a 206, so would be understeering everywhere normaly without the rack

Yeh, 'cos we all know how bad French cars are 😕 yawn...............