3T develops the Sparta ION e-bike

Cycling with the wind in your back

Sparta’s partnerships with various specialized companies has enabled it to develop a new generation of electric bicycle. A unique development, in which the cyclist’s needs have always been put first. An electric bicycle that looks like an ordinary bicycle and rides like one too. Its invisible technology makes the cyclist feel as if he has always got the wind behind him. This article describes how Sparta, part of the ACCELL group, developed the electric bicycle and its technical background.

A successful image

Despite the fact that Sparta already sells a lot of electrical bicycles, the product does not really breakthrough in all target groups. That is a petty, because it is a comfortable way of transpiration less cycling, which can replace the car in many cases. But to really bring the electrical bicycle in reach for all target groups, the current design had to be completely altered. Bicycle manufacturer Sparta anticipated this danger, and wanted to launch an entirely new generation of electric bicycles, which would be accepted and used by a broader and younger public. The new bicycle would have to look modern, and have all the features offered by an electric bicycle. In terms of marketing, the question was logical and clear; but how to develop something like that?

ION; the new generation electric bicycles

The new electric bicycle would have to be lighter and quieter, with electric parts that were less conspicuous. The result is an electric bicycle that is 5 kg lighter, quiet and looks like a normal, modern bicycle. Sparta has many years’ knowledge and experience in the development, production and sale of (electric) bicycles. Sparta would have liked to construct the bicycle from standard parts. Unfortunately, the components required were not available in the market, which meant that they had to be developed especially for the electric bicycle, ION. To make the electric components more difficult to see, it was necessary to integrate the components mentioned above into the bicycle. The basic concept for ION was formed by building the battery into the frame of the bicycle so that it could no longer be seen, and by placing the motor in the hub of the bicycle’s rear axle. The result was an elegant basic design, in which the most important electric components have been concealed from sight. In addition, it was decided to operate ION by means of a control unit (a sort of bicycle computer).

sparta ion fietsThe newest generation e-bike, the ION

In a nutshell, the following technical innovations have been made:

  • electronics integrated into the motor
  • serial communication network
  • advanced battery management system
  • advanced handlebar control-unit, with an LCD display
  • good theft protection; the electric systems stops working if the control unit is removed
  • long motor supported cycling range, due to increased efficiency
  • the motor automatically becomes a dynamo when the battery is empty, so that the lights always work, even when the battery is empty.

The development team

ACCELL – Sparta chose to develop the ION together with a network of specialised development companies. The right partner is crucial, so particular attention was paid to the technological knowledge already available, and the possibility of producing the products inexpensively. Sparta decided to have all of the electronic components required – including housing and software – developed by 3T BV from Enschede. 3T BV specialises in the development and provision of electronics and embedded software.
At an early stage, the decision was made to work with a supplier from China; it is already producing bicycle motors, and can alter the motor in line with the ION’s specific requirements. The motor had to be more intelligent, and a network interface was also added to allow the motor to communicate with all the other parts of the system. Besides this, a patented power sensor was integrated into the motor. When developing the housing and mechanics, 3T BV worked with specialised companies like Demcon and Indes.

Special ION parts

Electronic steering The various parts of the bicycle must be able to exchange information to be able to function effectively as a whole. Using a power sensor fitted to the axle in the motor, the main control module continually measures the force that the cyclist exercises on the pedals. Depending on the user settings, the control unit calculates the motor support required, and passes this information on to the motor, making it possible for the cyclist to peddle less. When the speed of the bicycle exceeds the legal speed limit, the motor support shuts off.
To keep the wiring simple, the bicycle has been equipped with a serial communication network. Power is supplied to all modules via this bush, and communication occurs between the various parts.


The motor has been placed inconspicuously in the hub of the bicycle’s back wheel, and is powered by a 24-Volt NiMH battery. The motor contains electronics that drive the coils of the direct-drive motor.
A good electric bicycle must have a motor that runs quietly and evenly. The power supplied by the motor must be continuous, and it must be possible to regulate it precisely. These demanding requirements can only be realized by making sure that the electronic control is geared towards the bicycle’s mechanical characteristics. Mechanical measurements were taken in collaboration with Demcon, so that – in consultation with the motor’s producer – an optimal motor could be developed.


Even if the battery is empty, a cyclist has to be able to use the bicycle’s lights. The electric energy required for this is generated by the motor in its dynamo mode. The electric voltage generated by the motor varies greatly, depending on the number of revolutions. The voltage needed for the bicycle’s lights to work is converted electronically into the standard 6-Volt voltage used for bicycle lights.

Control unit

The level of support that the motor supplies can be programmed using a control unit situated on the bicycle’s handlebars. It shows how much energy is left in the battery, as well as providing information about speed and the distance cycled. The information about speed is measured by the motor.

The control unit can also be used as a detachable electric lock when the bicycle is being left anywhere, a secure bicycle shed for example. ION’s electric support only works if the corresponding control unit is connected to the bicycle.

sparta ion bedieningsunit

The control unit

The battery: ‘electric peddling power’

Every ‘electrically supported cyclist’ wants to cycle as far as he possibly can, assisted by the battery power available. The battery’s electric storage capacity determines what this range will actually be. In addition, it must be possible to hide the battery away in the frame, and the bicycle (so, the battery too) must be as light as possible.
The battery chosen guarantees the cyclist the longest life span possible for the bicycle, as well as the greatest possible cycling range under the various conditions that it is used in.

sparta ion accu frame

The battery pack is integrated in the frame

Service terminal

It may not be difficult for bicycle dealers to maintain ION, even if they have never done any electric bicycle servicing before. A service terminal makes it easy for the bicycle repairer to service the bicycle.

For example:

  • diagnostic tests can be run on the bicycle within a space of several seconds;
  • if the control unit is lost, a new one can be installed;
  • it can keep information on battery use and history.

sparta ion bedieningsunit
The service terminal is connected to the ION bus

Electric bicycle with a great future

The technology described above guarantees ION a great future in our bicycle-loving country (and elsewhere); it is an electric bicycle that has been designed especially for people that could really do with the wind behind them. For more information on Sparta and the ION see www.sparta.nl