Designing a bike trailer with electric assistance (crowfunding "virtual")

[Grelinette]

This is the project currently on my work table!

I resume the construction of a new bicycle trailer chassis with materials within the reach of all, easy to find and economical, and I suggest you imagine how we could finance it by crowfunding.

Here are the main steps that I plan:

1 °) Imagine (draw) a bicycle trailer chassis, light and modular (*) for the transport of objects, goods, or the transport of children.
For ease of use, this trailer will be equipped with 2 standard bicycle wheels (2 front wheels) which will eventually be equipped with VAE motor kit (s)

2 °) Design and fix a simple suspension system on the axle / on the wheels / the platform:

3 °) Determine the electric assistance system: manual / auto, its power, the power of the batteries => choice of an VAE kit model on the market

4 °) Choose or Design the assistance trigger system (Manual / Automatic)

5 °) Choose or Design a security system to cut assistance in an emergency (automatic braking, button or joystick on the handlebars, both)

I will make a synthetic table which takes up each of the 5 stages defined with:

- Planning of the stage (rank, constraints, importance, ...)
- Technical knowledge required
- Possible solutions (sizing, choice of materials, advantages / disadvantages)
- Estimated duration of the stage
- Materials required
- Estimated cost (material purchases / labor / costs / other)
- Plans
- etc

If you have ideas or questions / preliminary thoughts to raise to properly organize and frame this project, especially in the context of crowfunding…

[chatelot16]

you do not specify what is the exact purpose of this trailer:
2 extreme:
1) light and efficient but expensive ... light enough to be usable empty battery ... motor bike wheel, 2 controller + specific microcontroller to control them ... common lithium battery

2) rustic and economical ... heavy and unusable without electricity ... automatic almost neutral for the cyclist as long as there is electricity ... wheel more solid than bicycle wheels ... lead acid battery. .. strong enough to be coupled also behind a car ... if necessary be charged while driving behind the car ... good for motorhome: allows to use the bike and the electric trailer to go where you can not go by bike ... can also be used on foot as a motorized wheelbarrow

[Obamot]

Some embryo ideas for "project management"

"Desk research": you have seen part of it since the project ends with a hypomobile coupling (there is already"know-how")
"Field research": it is necessary to find out whether something already exists in this area (and, if so, to ensure an innovation which will be the"more product"if not, it can be a very promising project! There it would be worth filing a / patents: to do with"inventive effort") Obviously, you have to go see what is being done in China.

And why not a trailer that can become "autonomous"(depending on needs, detachable tandem type). The interest is autonomy, a trailer can carry more batteries than a bicycle. + what Chatelot said.

Find alliances / industrial partners? Sponsors?

[Grelinette]

Hello Obamot,

Okay ! a more precise specification must be defined.

A trailer will never be neutral for a cyclist, even empty!

My thinking is purely empirical and practical: I bought a VAE (first price, therefore quite rudimentary) but as soon as I can use it for my daily transport, I use it. Little by little (the VAE being an addictive transport), I wish to be able to use it to go to work by transporting materials and tools, to make purchases in town, or to fetch my 2 young children at school.
Average distance: around 15 to 20 km AR per exit; therefore a mainly urban use which does not prevent being able to use it over a greater distance for a long walk or a hike.

The luggage rack is not enough where the choice of a trailer, but given the weight that the trailer will have to carry, I told myself that a motorized assistance, in addition to that of the VAE, should make this means even more useful and functional.

- It should therefore be able to be used with or without electrical assistance, therefore light
- quickly adaptable according to its use: transport of goods / materials / tools / children
- Strong enough to transport relatively heavy loads, say 50 Kg max, on road and dirt road (hence the choice of suspensions, especially since the bitumen of the roads is in very bad condition).

A priori, it is a basic Bicycle Trailer that will not have other uses without a bicycle (not behind a car), except perhaps for transport on foot, the trailer being pulled by hand (eg ride or picnic with the children).

For the moment, the objective remains quite modest for reasons of cost, difficulties in finding non-standard materials, and to avoid having recourse to specialized skills that are difficult to find or expensive.

I found on the internet various bicycle trailer design projects, either complicated to carry out, or expensive, or requiring specific know-how or tools that everyone has: this design project must be accessible to the average DIY cyclist.

So no extraordinary innovation, but why not imagine clever details (eg recharging batteries).

[Grelinette]

Remember that this project must remain modest for:

- be accessible and reproducible by the greatest number (so no high-tech which dissuades)
- stay within a "reasonable" budget to be within everyone's reach AND test possible funding by crowfunding

Possibly if this project leads to an interesting functional result, why not consider alliances, sponsors, marketing, or patent ... but this is another step and another pair of issues: "do not put the trailer before the cyclist" !

[chatelot16]

if your project must be achievable by anyone without great means, the result will be limited to what can be done with commercial electric bike kit ... it is not even sure that we find easy controller to order by 2

I think that designing a specific electronic controller is something that can be done in collaborative work more easily than a mechanical project, just a little less easy than a software-only project

an electronic controller specially designed to control 2 motors by managing a battery and with automatic effort control

it is possible with good effort control to have a trailer with practically neutral effect both for acceleration and braking

it is much more difficult to do with a motor controller which has a badly defined behavior: the additional circuit which one realizes to use the sensor of effort never succeeded in firing a reliable result because the controller does what is his head

when I say almost neutral effect, it's almost because you have to leave a small neutral zone so that the trailer does not waste its time pushing and braking at the slightest variation, but it is only a neutral zone not damping ... damping improperly placed in a servo produces oscillation ... this is the problem of a motor controller which has a somewhat long response time: it can be used in manual control and cannot be used in a servo

making a controller could be a completely independent project useful for the carriage as well as a light trailer or a heavy trailer

if I had to make this kind of trailer I would take a small trailer for car ... with a lead-acid battery

[phil53]

It seems important to me to have a command on the trailer (or a remote control) to be able to use it without the bike for short distances, in the garden etc.
The battery may also need to be easily removable for unattended trailer use.
Another way could be a trailer without motorization, only the additional battery, the engines would be on the bike and only additional braking on the trailer.
An additional module could also be considered, it would include foldable solar panels and a charger. Ideal for campers. It's luxury but if you think about it at the start, it will be easier to add it.
Make way for other ideas, even the craziest, you will then have to choose
In any case I am ready to help.

[Christophe]

Greli, I had already asked a question about the trailer-bike coupling but I did not have an answer I think ...

The coupling of most current bicycle trailers (mounting on flexible spring and only on one side of the frame) does not allow a secure coupling in the event of propulsion power in the trailer, there is also the problem of possible skating ... (if trailer too light compared to bike) ....

Before thinking about electronic management, power and batteries, you have to resolve mating concerns.

Basically we find ourselves in the same case as when we reverse in a car with a trailer! It is not necessarily obvious not to put the trailer in scissors !!

The coupling must be fairly rigid, applied as close as possible to the center of gravity of the bicycle and allow, of course, the rotation of the trailer at least on 2 axes (pitch and yaw) and 3 is better (for the damping in roll) .... in short, a ball joint!

So a small ball joint that would push on the saddle AND on the 2 points of the rear axle (to distribute the force close to the center of gravity of the bike and not have to make an assembly too heavy), seems to me not bad as first mechanical approach ...

Otherwise I support 200% the approach and the grelinette concept! Just reassure me on these 2 points ...

[chatelot16]

I have already put a trailer behind a motorbike: my simplest solution: tow ball like the car just behind the wheel as low as possible and as far forward as possible: under the tire

as rigid as possible ... no flexibility, no shock absorber

I happened to put heavy loads on a motorcycle, the slightest elasticity makes driving difficult

the ideal point to put the ball joint is the point of contact of the wheel with the ground: which is of course impossible: the ball just behind this point of contact is an approximate solution

it is possible to realize the ideal solution with a multiple lever mounting equivalent to a ball joint at the ideal point

[Christophe]

Under the tire? Do you mean staying in the tire plane (= longitudinal plane of the bike) when its curvature returns towards the bike?

For me the ideal assembly is to apply the driving force of the trailer to the center of gravity of the bike (passenger included of course) ... the case is different from a towed trailer ...