How to make a direct drive wheel motor with your own hands

To turn a bicycle into an electric bicycle, a carriage motor or a wheel motor is most often used. With the help of motor-wheels, you can implement front, rear or all-electric drive. Depending on the design features, wheel motors can be geared or directly driven.

The direct drive electric motor does not have a gearbox and provides a wheel speed that matches the rotor speed. Compared to geared models, direct drive motors:

• more reliable, very durable - due to the absence of rubbing parts and gears;
• allow the use of recuperation - the reverse conversion of kinetic energy of movement into electricity and replenishing the battery charge when braking without the use of brake pads;
• produced more powerful and heavier - weighing up to 10 kg or more, power up to several kW;
• more demanding on the thickness of the spokes, the strength of the rim, fork and frame, battery power, reliability of brakes and other components;
• with the same power, they provide reduced torque and less acceleration at the start;
• when using a powerful and heavy motor, they affect the inertia and maneuverability of the bicycle.

Asynchronous motor

Asynchronous ones are quite large and heavy; in this case we use a 750-watt one, which gives high efficiency and very powerful acceleration.

It is best to use bicycles with a high frame; by the way, if you have not yet decided on a frame, you can contact us, a bicycle rental company, and choose the size and shape that suits you.

In terms of speed, it will be inferior to motor wheels of similar power. But it will cost much less.

For assembly you will need:

- drive unit;

— controller;

- batteries.

Operating procedure:

1. We start by dismantling the sprockets on the carriage , remove the pedals and connecting rods - they will not be needed with this arrangement;

2. Then you need to make a drive mounting bracket.

The easiest way is if the base is steel, then you can set and weld a couple of profiles from a steel angle, for example.

Holes for the selected engine are marked and drilled in them.

Instead of welded brackets, you can make removable ones that will be held in place like clamps;

3. In this case, batteries are needed with a capacity of 12Ah and a voltage of 24V.

Several smaller ones can be connected in series;

4. Batteries weigh a lot, so they will also need brackets .

It’s worth choosing batteries so that they fit inside the frame, it’s more compact;

5. The easiest way to install the controller is closer to the batteries so as not to pull wires through the entire structure.

You can buy a small bag and secure it tightly, and put a control device inside;

6. Then the electrician: the wires are soldered, the charging connector is soldered.

We insulate unprotected areas with electrical tape or heat shrink.

If it is not possible to completely hide the wires, it is worth laying them in a cable channel to protect them from moisture and dirt.

The main problems in the manufacture of homemade MK

When manufacturing a motor wheel you will have to face several disadvantages:

1. The engine from a washing machine differs in appearance from a bicycle electric motor. It only has a stator and a rotor. It does not have a bearing or hub. Without a drum shaft, outside the washing unit, it is problematic to install and center it. To use such a motor on an electric bicycle, you will need a wheel bearing and a lathe to turn out the seat.
2. For the stator it is necessary to make a mounting ring. To do this, you will need a sheet of metal and a laser machine, or, in extreme cases, a milling and drilling machine and a grinder.
3. The motor from the washing machine has an inappropriate winding - aluminum, designed for a voltage of 220 V. It is necessary to rewind it to copper and adjust the voltage taking into account the on-board voltage of the future electric bike.
4. Washing machine motors have ferrite magnets. It is advisable to replace them with neodymium magnets, which is associated with additional costs. In addition, the rotor bowl should be reinforced with a steel ring and a closing system for magnetic fields should be created.

5. 
   The rotor bowl of the washing machine does not have protrusions with holes for installing spokes. You will have to take care of their implementation yourself. Therefore, spoketing a homemade motor wheel will require a little more effort than installing its factory counterpart.

Ready electric bike

The easiest and most reliable way to buy a ready-made electric bike is to get acquainted with the 3 most popular ones at the moment:

— Eltreco FS-900 26;

— HOVERBOT CB-4 X-Rider;

— WELT Rockfall 1.0 E-drive.

WELT Rockfall 1.0 E-drive

This is a 2022 model, costing 50-55 thousand - the most affordable option of those being considered. Class: mountain, cross-country.

The battery is 13 Ah, the sizes are varied, you can buy for riders from 150 cm or more.

The stock tires are quite grippy, even when driving on rough terrain. Among the shortcomings are weak brakes.

Eltreco FS-900

Double suspension from the budget price category - only 65 thousand. Class: cross-country, launch year: 2022.

It has a fairly capacious battery that can pull the rider up to 50 km.

Charging time – up to 6 hours. The backlight is integrated, and the front light is powered by a battery, and the rear light is powered by a small solar panel. Some users complain that the rear shock absorber is stiff, but it is not difficult to replace.

What is needed to assemble an electric scooter?

If you decide to assemble an electric scooter with your own hands, the most important thing is the selection of the engine and battery, since this vehicle runs on electric power.

The choice of one or another engine with a battery directly affects the maximum speed and mileage:

• If you take lead batteries, you can save a lot, but they are heavy and this must be taken into account.
• A more expensive alternative is lithium phosphate batteries, which are lighter.
• It is best to place the battery under the frame, where in addition to it the controller and alarm will be located. You need to leave at least some space under the seat for luggage.
• It is necessary to understand that assembling an electric scooter with your own hands necessarily involves welding work. If the necessary equipment, tools and skills are not available, then such an undertaking can be much more expensive than a finished electric model.
• But in any case, in the long run it will pay off due to the electric motor, which is much cheaper to refuel.

Set of ready-made components

It is very important to install the electric motor correctly. This is one of the most important points during scooter assembly. It is very important to minimize the sound it will make (it's not the roar of a Ford Mustang). This can be done due to the absence of a commutator and brushes. Often it is placed on the rear wheel, the rotation of which occurs thanks to an electrical circuit that supplies a push to the front one.

It is necessary to look for the necessary components for your electric scooter as responsibly as possible. You can buy an electric motor and battery along with the necessary connectors separately, or you can take the path of least resistance and buy a ready-made kit. Despite the fact that this one will cost more, you can immediately buy a set with a controller and a motor wheel, a charger and a set of hydraulic brakes.

Advantages and disadvantages

For many years now, some European countries have been actively fighting for the environment, so they have banned gasoline scooters. Electric analogues certainly have some advantages in this case:

• Much more modern design.
• The efficiency is much higher.
• There is no need for frequent repairs of the power unit.
• Easy to find spare parts.
• There is virtually no noise when driving.
• Easier to charge.

But they are not without drawbacks in terms of driving range on a single charge. However, for trips around the city this is the best option.

Will such a homemade product be safe?

From the point of view of risks to life - absolutely safe, from the point of view of the wallet - not everything is so simple, because if you don’t understand basic electrics at the level of plus to plus, and minus to minus, then you can burn not only the controller boards, but also the electric motor

The best thing that can happen if assembled incorrectly is that the homemade electric scooter simply won’t move. If you can’t wait to make such a vehicle yourself, it’s better to enlist the help of smart friends who can digest the frame and connect the system correctly.

Friction transmission

This type of electric drive, although found on sale, is not particularly popular. Its principle is simple. The engine is installed directly at the drive wheel, torque is transmitted directly from the stator shaft to the tire. It would seem that everything is simple and obvious. But what may be applicable for children's electric cars and bicycles is of little use in the actual use of transport.

Judge for yourself:

• There are no transmission links, that is, the possibility of increasing the angular speed of the wheel through the use of gearboxes is excluded;
• Extremely low efficiency;
• Even a slight drop in pressure in the wheel chamber will dramatically reduce the efficiency of such a drive.
• Constant friction between the engine clutch and the tire tread dramatically reduces its durability.
• In conditions of wet weather, dirty roads, frost, the friction coefficient will decrease significantly, the clutch will slip, which will reduce the already low energy output of the drive.

The only advantage of this system is its ease of installation, which does not require any major modifications to the bicycle.

No, if you are planning a modification with real improvements in the performance of the bicycle, it is better to immediately abandon such a scheme.

Tools for work

To make a good electric bike, turning work is required. You will need a machine or the ability to order the production of parts. In addition, the master should have the following tools at his disposal:

• welding inverter;
• plumbing kit (hammer, pliers, hacksaw, needle files, files, etc.);
• large caliper;
• electric drill and drills;
• head 15 for ratchet;
• Bulgarian;
• thread cutting tool.

You may need a milling or surface grinding machine, which depends on the components: whether they need to be remade or modified.

Thinking about the future

It is also important to imagine whether the model you have chosen can be installed on your bike. It will be a shame if you can’t remake your bike and need to buy a new one.

Can you do this work on your own, or do you need to look for a qualified bicycle mechanic with knowledge of electrical engineering, which is a very big shortage?

Determine exactly where the battery will be placed, estimate its dimensions so that the homemade electric bicycle is comfortable.

Installation of electrical equipment

Having installed all the parts, you need to assemble the electrical circuit. The complexity of this operation depends on the selected assembly elements. It is worth choosing reliable contacts to prevent heating and sparks.

Check it out here too!

• 
  What is an acoustic switch: device, operation, types and features of the device (100 photos)

• Low and high pass filter: making frequency filters and how to create high-end circuitry (95 photos + video)

• How to choose a gas boiler - the best models and manufacturers. Review of modern boilers and options for their application (145 photos and videos)

Useful tips and possible mistakes

When the engine and battery for the electric bicycle have been installed in accordance with the recommendations of experts, you need to test the finished bike. To do this, just ride it. During the verification process, the following problems can be identified:

1. The bike doesn't move. The problem occurs if the batteries are assembled incorrectly, the wires are disconnected, and the gear ratio is too high. To carry out diagnostics, lift the rear wheel of the bike, turn on the engine, and adjust the position of the intermediate shaft pulley. The cables must be carefully checked and the battery must be charged.
2. The bike is moving slowly. The main reason is the incorrect gear ratio. You need to perform similar actions with the intermediate shaft.

Converting a bicycle into an electric bike is quite difficult. To work, you will need a set of special tools and materials. In addition, the master must have the appropriate skills. The maximum speed, travel range, and ease of use of the bike will depend on the selected equipment.

Hardware interrupt

And then I realized what was going on: Arduino does not have time to process the readings of the Hall sensors! Therefore, it was necessary to use Arduino pins with hardware interrupt. Since Arduino UNO has only two such pins, and three pins are needed for sensors, you need to take Arduino Leonardo or Iskra Neo, where there are four such pins.

Having rewritten the program for interrupts and connecting Iskra Neo instead of UNO, I repeated the tests.

The wheel finally worked smoothly, without vibrations or noise, and began to pick up speed perfectly without desynchronization. The prototype turned out to be viable. But this is not yet a full-fledged controller, since it did not have protections and a high-quality PWM signal.

Retrofitting

You can improve the assembly with the following elements.

Wattmeter. This device is best placed on the steering wheel. It will show how far the remaining charge will last. This way you can adjust your route.

Controller. It can be a simple box with terminals, or using microcircuits. It is worth remembering that the resulting current will turn into heat. This is why high-quality cooling is important.

We recommend positioning the device so that it is blown with air while moving. The frame fits perfectly. Remove the paint, use an additional aluminum plate, lubricating it with thermal paste at the contact point.

Electrical signal. It will increase traffic safety.

Powering the headlight will also be very helpful.

For safer driving at night, you should consider illuminating the wheels using LEDs.

Advantages

• two types of movement - using a motor or pedals;
• availability of long-distance travel thanks to electric traction;
• ease of repair and maintenance compared to mopeds and scooters;
• environmental friendliness - no environmental pollution. For example, for Westerners, the use of such transport guarantees benefits.

Bottom line

The main advantage of the MC33035-based controller is its ease of use. You just buy a microcircuit, assemble an H-bridge, solder everything onto a board with a little wiring - and the controller is ready. If you just need to start the engine with a PWM signal and control it, this is the best option.

An Arduino-based controller is a more complicated option; you will need to write logic and provide additional protection for the controller. But for experiments, prototypes, additional functionality, and the use of different engine operating modes, it is a suitable option. Therefore, I decided to put the MC33035 aside for now and continue working with Arduino.

Bicycle models with motor

If you have available funds, instead of upgrading your bike, you can choose a ready-made bike with a motor. The classification of vehicles depends on their purpose:

1. City and highway models. They are equipped with tires without a pattern (slicks), designed for long trips on smooth, hard-surfaced roads.
2. Mountain bikes with motor. They are distinguished by increased power and variability in power reserve (from 20 to 50 km). Power is selected based on the weight of the cyclist.
3. Freight. They are equipped with a special compartment for transportation. It is usually installed at the front. Some models are equipped with two rear wheels for greater stability and reduced load on the frame.
4. Foldable. City bikes with an emphasis on compactness. They have low power and dimensions, with a frame folding in two or three places for easy transportation.

CityHighwayMountainTruckFolding

Regular motor wheel or geared?

It doesn’t matter whether the electric motor is connected via a chain drive (drives in the carriage) or not (front, rear motor wheel, friction gears), the bicycle speed system will still be involved.
The geared motor wheel allows you to move using a reduced gear ratio. It can help a cyclist climb a very steep hill if used with a motor with a high reduction planetary gearbox. This will cause the motor to operate close to its highest point of efficiency as it will maintain high revs. But still, a motor with a gearbox will lose efficiency, since such systems are complex and some friction costs are inevitable.

It can help a cyclist climb a very steep hill if used with a motor with a high reduction planetary gearbox. In this case, the engine will operate close to its highest point of efficiency, as it will maintain high speeds. But still, a motor with a gearbox will lose efficiency, since such systems are complex and some friction costs are inevitable.

The geared motor wheel allows you to move using a reduced gear ratio. It can help a cyclist climb a very steep hill if used with a motor with a high reduction planetary gearbox. In this case, the engine will operate close to its highest point of efficiency, as it will maintain high speeds. But still, a motor with a gearbox will lose efficiency, since such systems are complex and some friction costs are inevitable.

Geared electric bicycle wheel

Systems without gearboxes do not reduce engine speed. Consequently, the efficiency of the engine in them is not constant, but very often depends on the speed of the bicycle. But such systems are simple, so their total efficiency is higher compared to gear motors.

As you can see, there is a problem of choosing between electric motors with and without gearboxes. On the one hand, the former can maintain the same engine efficiency over a wide range of speeds, while the latter have inevitable losses when the speed decreases. On the other hand, electric motors without gearboxes have a high total efficiency.

However, it is safe to say that in other riding conditions, a motor without a low gear will do a better job (especially on frequent long trips) than an overly complex geared system.