Electric Bikes

[ProfJohnL]

I have a newly purchased 2019 Sterling Eccles 590 fitted with a rear mounted bike rack and tow with a RR Sport.The Thule bike rack has a max load of 60kg which will exceed the combined weight of my two electric bikes at approx 50kg .My question is ,how do you lift them onto the rack ? Has anybody any experience of towing with electric bikes on the rear mounted rack ?

Hello again Peter,

I think you can assume that no one else has towed with electric bikes on the rear of a caravan, otherwise I'm sure they would have commented by now. What you have received is the wisdom of several caravanners who have had differnt experiences, and in particular the concern shown for what in the UK is not a widespread practice of rear mounted bike racks.

Where your question differs is your intention to use electric bikes, and I and I am sure others have assumed such bikes will typically weigh more than normal bikes and will thus make your plan more extreme than if it had been ordinary bikes.

Quite clearly there is a market for rear mounted bike racks. They are quite common on the continent, but not so common here in the UK. There are a number of reasons why the practice is less common here than abroad.

Many UK caravans do not have the necessary body strength to carry a rack and bikes, so obviously its a no-no for them. But some caravan manufacturers do make provision for racks on some of their models - check with the dealer or manufacturer for details about each specific model.

Generally UK specification caravans have more internal fittings and home comforts than continental vans which uses up more payload capacity, which obviously might preclude the additional weight of bike and rack.

There seems to be a preference for continental caravans to have longer drawbar length. This tends to make them tow with slightly better stability characteristics, and that should accommodate the additional end loading of a bike rack with less risk.

If the caravan manufacturer has made provision for a rear mounted rack, they will also have specified the maximum load that can be hung from the rear wall. Don't forget that would be the weight of the bikes including the weight of the rack. - would that still be within the caravan manufactures weight limit?

I haven't checked but I suspect the caravan manufacturer will not have designed the actual rack, and will either offer an off-the-shelf rack as an option, or expect the owner to source their own rack. In either case, do not assume the load capacity of the rack is the same as the maximum load capacity of the caravans rear wall - Always check.

The video's that have been linked to this thread that demonstrate instability due to load distribution should be a wake up call to caravanners, but the videos are an very extreme example to demonstrate the yaw inertia effect. Caravans don't have half their weight at the ends and no weight in the middle, so it is possible to tolerate some end loading, but it is better and safer to avoid it if you can. Incidentally the full report that spawned this demonstration clearly links yaw inertia and speed to trailer instability.

If the figures add up for you fine - try it, but no one here can offer a copper bottomed guarantee that your particular outfit will be fine.

My personal concerns are, with the weight of the rack and the bikes at the rear, you may need to add substantially more load at the front of the caravan to achieve a sensible nose load figure, and that increases the yaw inertia even more.

 

[Jcloughie]

Thanks for your responses, I have yet to hear from anyone who from experience has used the rear bike rack to transport their bikes.

You are correct that your specific question has not been answered. This might be because even those who have the fixing points on their vans do not use them or intend to use them. Perhaps because, even if the fixing points can take the weight OK. It is still an illogical thing to do. I have even read that some make sure that the rear mounted toilet flush is fully drained in case it causes stability issues!

I suspect the responses you have received are people voicing their genuine concerns.

Looking on the roads I have seen these fixing points used on motorhomes, but never on caravans.

John

 

[Tobes]

Actually the fella who i was talking he said he fasten them in and they did not move and he had no problems so far

Same - I have put two regular (none e-) bikes in the van. I use a picnic blanket to separate them from each other and from the furniture, and then use 3 or 4 bungee cords, mostly from the oven and grill door handles and cupbaord handles in the kitchen to secure them. So far, no marks on bikes or furniture, and no coming loose

 

[Beachball]

Same - I have put two regular (none e-) bikes in the van. I use a picknick blanket to separate them from each other and from the furnature, and then use 3 or 4 bungee cords, mostly from the oven and grill door handles and cupbaord handles in the kitchen to secure them. So far, no marks on bikes or furniture, and no coming loose

I am pleased someone else does it like you he had no problem

 

[Pfcmike]

I bought 2 ebikes intending to carry them on the car (Thule) roof bars, however the max recommended weight for each roof bar is 20kg, each bike with the battery removed weighs 23kg so too heavy. I have done a few long trips with them inside of the caravan. I cover them with blankets and wedge them tightly so they can’t move, haven’t had any damage or towing issues so far. I would never consider carrying them on the rear of the van.

 

[Beachball]

I bought 2 ebikes intending to carry them on the car (Thule) roof bars, however the max recommended weight for each roof bar is 20kg, each bike with the battery removed weighs 23kg so too heavy. I have done a few long trips with them inside of the caravan. I cover them with blankets and wedge them tightly so they can’t move, haven’t had any damage or towing issues so far. I would never consider carrying them on the rear of the van.

Looks like a lot of people carry the ebikes inside the caravan and with no problems

 

[Buckman]

I bought 2 ebikes intending to carry them on the car (Thule) roof bars, however the max recommended weight for each roof bar is 20kg, each bike with the battery removed weighs 23kg so too heavy. I have done a few long trips with them inside of the caravan. I cover them with blankets and wedge them tightly so they can’t move, haven’t had any damage or towing issues so far. I would never consider carrying them on the rear of the van.

I don't think it is the actual bar that is the issue however the load on your roof of your car may be low. We have the Thule roof bars whowever on the Jeep Grand Cherokee and maximum load on the roof is 60kg.

 

[Dustydog]

There are two problems with using a rear mounted bike rack. The first identified by Tobes is the stability issue which could be a problem, and the rack is in the worst place possible for this. Many people manage with this, but it is a very definite risk although the video clip is an extreme example and I would not be swayed by that.

The second problem I see is that in standard form the caravan has a load allowance of only 158 kg . It is a large six berth, and if used in this way will need all of that just to stay within the MTPLM. If you take 60 kg from that for the bikes and the weight of the rack you are down below 100 kg for the load and this is practically unworkable for two and impossible for a family. The situation would be even worse if it has a mover fitted as allowing 30 kg for that will get you below 70 kg so you would be stuck with virtually no way of carrying anything of consequence.

Not sure if it can be upgraded to a higher MTPLM, but if so this might help but basically on the weights issue this is probably a none starter. In my mind this is more serious than the position on the caravan although that is not that good. Swift fix the fittings for a rack, but do not give the caravan the weight capacity to use it.

Ray hit the nail on the head above. Two e bikes stored on board the caravan , inside or out will seriously erode your load allowance.
For me carrying bikes inside is a no no. The interior is relatively delicate, the hard and soft furnishings easily damaged . Someone mentioned using bungies attached to oven and grill and cabinet handles. My Thetford Spinflo, fitted in most caravans, does not have lockable doors. They are push click and pull. Two heavy bikes moving around will soon pull them open imo.

 

[Raywood]

Thanks for your responses, I have yet to hear from anyone who from experience has used the rear bike rack to transport their bikes.

I think in your case it is almost impossible to carry them on the back and stay legal unless you have an upgraded MTPLM as without that you have no capacity to carry anything meaningful in the caravan. Even carrying them in the caravan saves only a few kilos so even that may not be the answer unless you can get Swift to upgrade the MTPLM. Unfortunately they no longer make an equivalent model so I have not been able to check what it can be upgraded to, if this is possible. If you have the brochure or handbook you could try them.

 

[Mandarin]

Twenty years ago we had a Hobby as our first van when we knew nothing about caravanning. It had a bike rack on the rear fitted by a previous owner. We used it for small kids bikes with no problem, the adult bikes went on the car roof . I would never have dreamt of hanging 60 kgs on the back of the van.

 

[Raywood]

I think you might find the old Hobby had a higher load allowance which would have helped.

 

[Darren.H]

We have a pair of Cube ebikes, firstly remove the batterys in case of accident.

The weight is in the electric motor, I take the front wheels off, batterys out, pedals off then twist the handle bars, bungee strap them then stick them in the back of the estate car, a duvet separates the pair.

I couldn't imagine with todays small payload being able to carry them anywhere in or on the caravan, I hate to think of the stability issues if put on swifts rear bike rack.

 

[ProfJohnL]

We have a pair of Cube ebikes, firstly remove the batterys in case of accident.

The weight is in the electric motor, I take the front wheels off, batterys out, pedals off then twist the handle bars, bungee strap them then stick them in the back of the estate car, a duvet separates the pair.

I couldn't imagine with todays small payload being able to carry them anywhere in or on the caravan, I hate to think of the stability issues if put on swifts rear bike rack.

I concur that end loading is better avoided, but it isn't always going to automatically cause a catastrophe. It does depend on the particular outfit, and the way the rest of the load has been distributed. Its not a black and white situation, though I suspect in teh OP's case it's dark grey rather than light.

 

[Raywood]

Agreed, it can be done on many caravans if managed correctly but I think the weight problem is the killer here. This is a six berth model which I assume is for a family given the layout. There is no way I can see the bikes being mounted anywhere on the caravan and still have a useable payload, even if the MTPLM can be increased.

 

[Hutch]

I know we have seen the video of the effect of weights on a trailer, but here is one showing the effect of hanging a bike on a rack on the back of a caravan, its worth a look.

View: https://youtu.be/KlD7THCoypk

 

[Dustydog]

Physics doesn’t lie👏

 

[Raywood]

It does show the problem but most of all t shows that higher tow car weights help control any problem. For those who decry the idea of a good towing ratio it shows the dangers of their idea.

 

[Old_Dave]

Not exactly on topic (but close in a sideways kinda way)

There is another method .of transporting e bikes

 

[ProfJohnL]

Thank you hutch for finding that clip. It is a good visual lesson about how loading can affect the characteristics of an outfit, However it is open to some criticism:-

Demonstrations like this can only be considered as a proof of concept, and to make the point the demonstrations often take matters to an extreme. Yes, very visual and thought provoking, and it does make a very serious point. But you need to ask yourself is the demonstration a fair or reasonable representation of real life or even life in the extreme!

I am in no way suggesting that anybody should ignore the issue of end loading, it is undoubtedly wise to avoid it if you can, but in reality caravans already have some end loading becasue of the the body work and fittings, and in some cases a modest additional end load may be a perfectly satisfactory solution. But it should always be approached with caution.

In much the same way as the a the Bailey model, this model is so far away from what could occur in real life, it's almost doing a disservice.

One of the biggest problems with these demonstrations is the representation of the trailer. In the context of caravans, neither model is a realistic representation of a caravan and come to think of it teh cars are no better. Specifically caravans have bodies and internal fittings as well as the chassis which combined makes up the MIRO of the caravan. The way the internal fittings are located will change the effective density of the caravan per unit length and generally a caravan will be more dense near the middle over the axles, becasue of the kitchen and sometimes storage and don't forget chassis and axle(s) as that also contribute to the mass of teh caravan.

In most UK caravans the difference between MTPLM and MIRO is the load margin and is typically only about 10 to 15% of the MTPLM. That includes things like the cooking utensils and food, the battery, the caravan mover, so most caravans when towed have a significantly greater density over the axle meaning the ends of a caravan are somewhat less dense.

These model caravans do not follow the true load distribution nor the proportionality of weight.

The demonstrator started with 5 magnetic weights in front of the axle and 7 weights behind - this is already contrary to normal towing practice when you have a slight bias the other way to create a nose load. This model probably had a negative nose load to start with!

Some of the weights were moved around to give a total of 8 in front of the axle which included a 3 on the A frame, and only 4 behind the axle but close to. It is often forgotten that loading at the front is also adding to the yaw inertia, when teh bike was added more than 2/3 of the total mass load could be considered to be unrealistic

Then there was the ridiculous amount of roof rack load put on the, at one point it had 13 magnets on top that equalled the number of magnets in or on the caravan!

As I have said, it is a very graphic demonstration of how yaw inertia from end loading might in theory affect an outfit, but the demonstration was so far from what could happen in reality its a scare tactic. Despite the over exaggeration shown in the demonstrations we should actively reduce end loading if possible.

 

[JTQ]

The importance of the square law relationship of the distance of masses from yaw centre gets no mention. Even here with the extreme case of two e bikes having a mass typically over thirty percent of the loading, positioned not within but beyond the van.

There is absolutely nothing analogous between hanging the concentrated mass of two e-bikes beyond the caravan, and anything found within the caravan build.

 

[Hutch]

Thank you hutch for finding that clip. It is a good visual lesson about how loading can affect the characteristics of an outfit, However it is open to some criticism:-

Demonstrations like this can only be considered as a proof of concept, and to make the point the demonstrations often take matters to an extreme. Yes, very visual and thought provoking, and it does make a very serious point. But you need to ask yourself is the demonstration a fair or reasonable representation of real life or even life in the extreme!

I am in no way suggesting that anybody should ignore the issue of end loading, it is undoubtedly wise to avoid it if you can, but in reality caravans already have some end loading becasue of the the body work and fittings, and in some cases a modest additional end load may be a perfectly satisfactory solution. But it should always be approached with caution.

In much the same way as the a the Bailey model, this model is so far away from what could occur in real life, it's almost doing a disservice.

One of the biggest problems with these demonstrations is the representation of the trailer. In the context of caravans, neither model is a realistic representation of a caravan and come to think of it teh cars are no better. Specifically caravans have bodies and internal fittings as well as the chassis which combined makes up the MIRO of the caravan. The way the internal fittings are located will change the effective density of the caravan per unit length and generally a caravan will be more dense near the middle over the axles, becasue of the kitchen and sometimes storage and don't forget chassis and axle(s) as that also contribute to the mass of teh caravan.

In most UK caravans the difference between MTPLM and MIRO is the load margin and is typically only about 10 to 15% of the MTPLM. That includes things like the cooking utensils and food, the battery, the caravan mover, so most caravans when towed have a significantly greater density over the axle meaning the ends of a caravan are somewhat less dense.

These model caravans do not follow the true load distribution nor the proportionality of weight.

The demonstrator started with 5 magnetic weights in front of the axle and 7 weights behind - this is already contrary to normal towing practice when you have a slight bias the other way to create a nose load. This model probably had a negative nose load to start with!

Some of the weights were moved around to give a total of 8 in front of the axle which included a 3 on the A frame, and only 4 behind the axle but close to. It is often forgotten that loading at the front is also adding to the yaw inertia, when teh bike was added more than 2/3 of the total mass load could be considered to be unrealistic

Then there was the ridiculous amount of roof rack load put on the, at one point it had 13 magnets on top that equalled the number of magnets in or on the caravan!

As I have said, it is a very graphic demonstration of how yaw inertia from end loading might in theory affect an outfit, but the demonstration was so far from what could happen in reality its a scare tactic. Despite the over exaggeration shown in the demonstrations we should actively reduce end loading if possible.

Sorry Prof, I think the video shows how much a change in balance of the caravan can be effected by positioning the internal items.
What it does, not show is the maximum, allowed weight for the caravan or the towing vehicle. All that weight on the towing car could be too much.
But it shows how a load on the very back of a caravan, is not the best place to carry heavy equipment. It is not far from the truth as I found out after over loading the under bed of my Coachman 545, towed by a SantaFe.,

 

[Raywood]

I think what the video does is show the potential for problems with the various loading options. Basically it proves that the heavier the tow car in comparison to the trailer the better, good loading of a trailer helps and weights at the rear are bad. I think we all knew that though. Trying to go further than that on the basis of the demonstration is a step too far.

 

[Dustydog]

The Triorep model , like Bailey , Al-ko and the boffins at University of Bath have all over many years produced models to demonstrate the instability of a caravan / towing vehicle where the various loads are not correctly distributed or weight ratios go outside the usual recommendations.
I argue the model on here has demonstrated to destruction the problems of incorrect loading. Isn’t that what scientific investigation, research, experiments and CAD s is all about?
The denigrating comments from some on here I find most disingenuous and possibly misleading to those who may be interested in learning more about the dynamics of towing. A lot of new tuggers will be on the roads soon once the revised licence law comes into force.
If this particular model is so flawed could someone with knowledge suggest a better alternative please??

 

[ProfJohnL]

The importance of the square law relationship of the distance of masses from yaw centre gets no mention. .... There is absolutely nothing analogous between hanging the concentrated mass of two e-bikes beyond the caravan, and anything found within the caravan build.

JTQ, I did mention Yaw inertia and the distances from the axles. And the effects of the caravan construction which adds the mass of the walls, windows and other structures in the caravan affect the yaw inertia in exactly the same way as adding a bike rack. It's a question of the scale of the effect, and how the true relative scale of the effects was not being demonstrated. That was the point I was making.

Sorry Prof, I think the video shows how much a change in balance of the caravan can be effected by positioning the internal items.

Yes I agree it most certainly does.

What it does, not show is the maximum, allowed weight for the caravan or the towing vehicle. All that weight on the towing car could be too much.

And yes again, the models was not a fair representation of a real situation, the exaggerated loadings produces exaggerated results.

I think what the video does is show the potential for problems with the various loading options. Basically it proves that the heavier the tow car in comparison to the trailer the better, good loading of a trailer helps and weights at the rear are bad. I think we all knew that though. Trying to go further than that on the basis of the demonstration is a step too far.

In principle I do agree heavier tow vehicles are generally a better bet, but the problem is we don't know if the weights of the models used in the demonstrations were scaled accurately. judging by the ridiculous amount of roof load on the car I suspect they were not. So in that respect it's not a good demonstration of weight ratios, but then that was not its purpose, but its how viewers might conceive it.

The Triorep model , like Bailey , Al-ko and the boffins at University of Bath have all over many years produced models to demonstrate the instability of a caravan / towing vehicle where the various loads are not correctly distributed or weight ratios go outside the usual recommendations.
I argue the model on here has demonstrated to destruction the problems of incorrect loading. Isn’t that what scientific investigation, research, experiments and CAD s is all about?
The denigrating comments from some on here I find most disingenuous and possibly misleading to those who may be interested in learning more about the dynamics of towing. A lot of new tuggers will be on the roads soon once the revised licence law comes into force.
If this particular model is so flawed could someone with knowledge suggest a better alternative please??

Dusty, I have been at pains to reinforce the view that end loading should be avoided. I also fully acknowledge the demonstration models do indeed show the principles of the effects of end loading, and it is a forceful message its sends. However when it is reviewed from a more scientific approach, the actual models do not accurately represent the weights and loads that are really involved.

However this demonstartation is not about a particular product, it's about the principle of trailer loading. and it's a marketing model not a scientifically accurate model as such . Great for demonstrating the principle but not a means to make meaningful simulations of real life cars and caravans. As such anyone wanting to understand the dynamics of towing may benefit from seeing the model to understand the principle, but is not close the scale of real thing. I have only been trying to put the demonstrations into perspective in the context of real caravans.

No one should underestimate to potential effects of yaw inertia.

 

[JTQ]

JTQ, I did mention Yaw inertia and the distances from the axles. And the effects of the caravan construction which adds the mass of the walls, windows and other structures in the caravan affect the yaw inertia in exactly the same way as adding a bike rack. It's a question of the scale of the effect, and how the true relative scale of the effects was not being demonstrated. That was the point I was making.

It can't be "in exactly the same way" as all those masses are within the van and the bikes and rack masses are beyond the van.
So salient in this, is that it is distance squared that drives the yaw inertia.
Thus, something of heavy mass outside beyond the van, has to be further from the axle, where the squaring of that offset distance becomes so powerful a driver.

It is not "the distances from the axles." but the square of the distances.