Ontwikkeling van de software voor een controller voor elektrische fietsen
IDbike ontwikkelt en produceert componenten voor elektrische fietsen. Deze componenten worden uitgeleverd aan fietsfabrikanten over de hele wereld. Naast een koppelsensor die inmiddels in grote aantallen wordt geproduceerd, houdt IDbike zich ook bezig met controllers en displays voor Ebikes, en de software die hiervoor nodig is.
IDbike is bezig met de ontwikkeling van een nieuwe generatie controllers, die een factor kleiner moeten worden en toch meer functionaliteit zullen hebben, zoals Bluetooth support
IDbike zoekt een creatieve en slimme student die daar aan mee kan werken. Hierbij moet zowel de software voor de nieuwe controller en bijbehorende app worden ontwikkeld, als meegedacht worden over de implementatie in de hardware.
Kennis van programmeren, met name in C en Java
Kennis van CCS, GIT
Ontwikkelen van een app voor de communicatie met de controller
Implementatie van Bluetooth hardware en software
Testen van de oplossingen in de praktijk
Stage wordt uitgevoerd in Riel
Student kan ervaring opdoen met het hele bedrjfsproces bij IDbike, van ontwikkeling tot productie en verkoop
Combine our sensors, displays and controllers to create full control systems. All components work together seamlessly, with software that guarantees a smooth functioning drive system. Our complete systems comply with EN15194.
Why use our complete systems?
We tested the main available systems on the market (i.e. Bosch, Panasonic, Yamaha) and compared them to our own systems.
The outcomes? E-bikes using our systems perform better, especially compared to systems using centre motors, like Bosch. At the same time price-quality relationship is much better. Last but not least, our systems are much more flexible in the application than the competition, because we develop and adapt our systems in collaboration with our customers, to meet your requirements.
Feel the ride
We at IDbike believe that any electric bicycle must:
Start in a safe and controlled manner, in all riding modes (eco to boost).
Be intuitive, through a swift and reactive response on the cyclist's pedal torque input. The pedal support is obvious and natural like power steering. Perfect and harmonious synergy between man and machine, riding your bike without worries and without thinking.
Be repeatable and reproducible under all circumstances, with ride predictability and stability.
Have no influence of:
Aging of the bike and drive system
Weather conditions and temperature
Weight of the rider
Road conditions and vibrations
IDbike has lots of experience with software development for electric bicycles. Software has a big influence on the riding feeling. It can make or break the bike. With IDbike's software the bike will have the optimal response and support level, resulting in a great feeling and a smooth ride!
Why use a hub drive system?
With the entrance of the Bosch mid motor concept in the market, many companies and consumers are convinced that this is a superior system compared to hub drives.
The mid motor drive has some advantages, which especially are valid for more sportive bikes like mountainbikes. The middle motor has a better performance on steep hills, and gives the bike a low centre of gravity. Also the cabling is reduced due to component integration, so the system is potentially more reliable.
For most bicycles however hub drive systems are more suitable, because of the following advantages:
are more silent and give no vibrations in the pedals
can be combined with every kind of shift system
result in less load in the drive line, and less friction and wear
have a superior efficiency at high speeds
have the possibility of regeneration
have no friction when the bike is used without support
are more simple to integrate in the bicyle, and do not change the looks of the bike
can be serviced more easily at less costs
are more cost effective
Here you can find an interview with a cyclist who decided to move to a Stromer hub motor system.
Obviously IDbike has choosen to focus on hub drives. We are convinced of a bright future for hub drive applications, so our systems have been developed especially to optimise the performance of bicycles with a hub drive.
IDbike develops electric bikes which put a smile on your face. These are bikes with intuitive support of the rider, which feel like a normal bike, and give a smooth and effortless ride
IDbike also produces and offers dedicated products for electric bikes such as torque sensors, controllers and displays.
Apart from components, we offer a high quality development capacity, to develop and improve products, especially electric bikes. Our developments are executed in close collaboration with our customers in the bicycle industry. We perform complete developments, from idea generation to prototype construction and testing.
We were closely involved in the development of the first electric bicycles. Read more about this here.
IDbike is a member of the Light Electric Vehicles Association. We are ISO 9001-2015 system certified.
Looking for new colleagues!
Traineeship software development
IDbike is looking for a student who likes to develop software and apps for our new controller.
More information about the traineeship you can find here
An electric bicycle can be controlled in different ways, making use of a torque sensor or speed sensor. Many e-bikes get their input from speedsensors or rotationsensors, mostly located in the crank. These sensors just register if the cyclist moves the pedals or not and only can switch the support on or off. Therefore the amount of support only be regulared by manually changing the level by the cyclist, and bikes with speed sensors cannot offer the same intuitive riding performance as a torque sensor.
A torque sensor however gives the possibility to sens the level of effort of the cyclist, and to control the amount of support of the motor in accordance. A torque sensor also has a better respons on the actions of the rider, when the starts of stops the bicycling, the torque sensor will sens this instantaneous.
IDbike provides various sensor systems for measuring the crank torque.The TMM4 measures the torque of the cyclist accurately which enables a riding behaviour that feels smooth, natural and comfortable.
The TMM4 Sensor
The TMM4 sensor has the world's best price performance. It is a patented development of IDbike, and can be used for measuring the crank torque of the cyclist. Because of its high precision this sensor can be applied in electric bicycles as well as in power measurement systems. Here you can find is a nice example of the application of our TMM 4 sensor
Due to the sensor’s low profile the rear drop out can be designed so that it covers the sensor completely. This way the sensor is fully protected and the appearance improved.
The TMM4 sensor consists of a housing of engineering plastic, which holds a printed circuit board (pcb) , a magnet and a small set screw, which is used to calibrate the zero value
The sensor, mounted on the sensor plate, measures the deflection of the plate caused by the chain force. This, in turn calculates the pedal torque of the cyclist. The deflection is detected using Hall technology and is maximal 0.1 mm.
The sensor is connected to the control unit with a 3 wired cable. The sensor can be hardwired or can be connected with a small connector.
The printed circuit is protected against moisture, salt and dust, by a special coating. The sensors are tested by immersion - in operationt - in salt water for at least one week.
And of course our sensors are tested under extreme outdoor conditions:
An important aspect of the successful development process of bike components is the testing of the functional and durability aspects. Thorough testing is essential to provide feed back to the development department, which contributes to the creation of optimal bike components.
Before entering the production phase, there has to be a certainty, of whether a bike and its components will meet the needs of the customer, and the required standards ( DIN, ISO etc.).
Testing is also important to provide the customer with objective information about the characteristics of their future bike.
IDbike tests for you
IDbike is well aware of the importance of testing bikes and their components, and has developed several test methods for testing bicycles.
IDbike has constructed a special test rig to validate the strength and functionality of the drive line and also has various possibilities for mobile testing.
Furthermore IDbike has a special facility for testing the efficiency of chain drives.
The development of our unique test bench started about 10 years ago, and was originally intended to test the functionality and the durability of a bike CVT (a Continuously Variable bike Transmission). The test bench was further optimised for universal application of all types of bicycles and bicycle drive-lines. The test bench also proved to be a very useful piece of equipment for the testing of conventional and electric bikes. At the present time it is one of the most accurate instruments in Europe available to the bike industry.
The test rig is based on a roller bench, on which the test bike is mounted. The crank of the bike is driven by a servomotor (1) and the rear wheel runs on a braking wheel (2), connected to a second servomotor (3). Besides the speeds and torques of both motors and the rear wheel, the voltages and currents of the battery and the electric motor of the bike are measured simultaneously. With this information the efficiency of the bicycle can be calculated, and the amount of support and the range at different speeds can be determined.
For electric bikes the partial efficiencies of the battery, the converter, the E-motor, the transmission and the tyre can be made visible. The max. test bench specifications are:
Crank torque : max. 250[Nm]
Crank speed: max. 200 [rpm]
Testing electric bicycles
With more and more electric bikes on the market, and the high consumer interest in these bikes, there is an increasing need for objective information about the performances of these bikes. The consumer is interested in the amount of support of the electric drive, and especially in the range of the bike. Although the average travel distance of most consumers is less than 10 kilometres, almost everyone wants to have the possibility to cycle a much larger distance.
To provide objective information about the performance of electric bikes, IDbike has developed a specific test cycle, like the ECE cycle for cars. These kinds of tests are performed on a roller bench at standardised conditions, with which a good reproducibility and reliability is guaranteed. On the test bench an average bike ride of an average consumer on an E-bike is simulated, which gives a good indication of the range and support that can be expected in practice. Most important is that the bicycles can be compared with each other in an objective way, which could help the consumer to make a good choice.
Finally testing according this cycle can also be an important tool for a fast and better development of power assisted bicycles.
IDbike is capable of performing a complete development project, from idea generation to prototype construction and testing. A rough outline of a typical project could look like this:
1. Identification of the needs of our customer
It's very important that we fully understand your design problem, and one of the ways to ensure this is the use of the QFD (Quality Function Deployment) technique. As a result of the QFD process clear engineering targets for the project can be set.
2. Presentation of the specification sheet, the planning and the budget
A proposal will be presented to our customer, so he will be able to take the go/nogo decision.
3. Concept generation
First the design problem will be simplified by decomposing it into sub problems, that can be managed more easily. This decomposing technique will show clearly which function the new product has to perform. As the people of IDbike are very creative, and cyclists themselves, a large amount of possible solutions will be generated. Also IDbike uses special software to come up with unexpected other solutions. Furthermore the patent literature will be searched, and existing solutions will be analysed. All idea's and alternatives will be evaluated and the decision matrix method will be used to extract the solution(s) with the best price/performance.
4. Development and construction of prototypes
The prototypes will be developed with the use of 3D-design software, and FEM analysis. The first models can be produced with stereo lithography, and will give the customer a good indication of how the final product will look like. In our fully equipped workshop also functional prototypes can be produced, with which the technical feasibility of the product can be evaluated. Also the FMEA (Failure Mode and Effects Analysis) method is used to get an indication about the possible failure modes in practice and the risks for your customer.
5. Product development
When the technical feasibility of the product is sufficient, the product development can start, again with the help of 3-D design software, and techniques like Design For Assemble. When the design is completed, STL models can be produced, to manufacture the production tools. IDbike has a lot of know how of the various production processes (sintering, lost wax casting, vacuum casing etc.), and good relationships with producers in Europe and the Far East, we can recommend a suited process and manufacturer for your product.
6. Production support
IDbike can provide you with technical support of the production of your bicycle product. We have experience with production control methods and statistical analysis of the production process, and the required test methods.
7. Testing and Validation
A very important aspect of the development of bike components is the testing of both functional and durability aspects. Before entering the production phase, there has to be certainty, whether a component will meet the ISO, DIN or other certification requirements. IDbike is well aware of the importance of these certifications, and has constructed a special test rig to validate the strength and functionality of bike components.
Track record of IDbike
During the last years IDbike has contributed to the following projects:
1999: Concept & design of Sparta ION (still today #1 European E-bike)
2005: Development of JD TranzX E-Drive system
2006: Development of Gazelle Innergy ( Bike of the Year 2009)
2009: Development of Ultra Motor A2B Hybrid
2013: Development of the control and display system of the the Dumar EDEN
Also IDbike performed a lot of measurements of various components, like speed hubs, chain systems and electric motors
The future of cycling is electric. Already about 20% of the bicyles sold in the Netherlands is electric, and this figure is expected to raise above 30% in the future. IDbike develops electric bikes since about ten years, and has much experience with the layout and the optimal components. IDbike has developed the first Sparta Ion prototype, and contributed to the Gazelle Innergy. Already five large bike manufacturers and a number of small companies use the TMM technology of IDbike.
Do you consider developing a electric bike? Do you want high quality, performance and flexibility and still have an excellent price efficiency? Just contact IDbike!
IDbike develops and supplies components for electric bicycles. We supply the complete control system: pedal force sensors based on the patented TMM4 principle, motor controllers and handlebar displays.
Power measurement in bicycles is another expertise of IDbike. The latest TMM sensors are highly accurate, so they can be used in power measurement systems. Because out of the TMM signal also the frequency can be obtained, there is no need for an additional crank speed sensor.
The low costs of our sensor makes it possible to install the system in almost every bicycle. This creates the potential for completely new applications, like trekking and mountain bikes.
The TMM technology originally was developed for the application on electric bicycles. The sensitivity and accuracy of the TMM sensors is however high enough for power measurement.
IDbike already equipped several bicycles with a TMM sensor to measure power. Also a display has been developed on which the following information can be shown:
Hearth rate frequency
Time and Training time
Total distance, energy and calories
Left/right leg power comparison
2 Graphs for Torque/Power/HF/Crank speed
The display has a USB connection to transfer the measured information to a PC. There the signals can be viewed and evaluated. Also a real time display is possible, for instance to evaluate the left/right power distribution and "roundness" of pedalling.
Prototype bicycles that have been equipped with the IDbike power measurement system are:
BMX bicycles for the Dutch Olympic team
A trial bike to evaluate the torques at trail biking
Power measurement System for BMX
For the Dutch olympic BMX team, IDbike has equipped 2 BMX bicycles with the TMM sensor data aquisition system. With this system, the olympic riders were able to evaluate and improve their start performance. A good start is very important in BMX competition. The rider which which is ahead of the pack after the first 10 meters will almost certainly win the race.
A second bike was equipped with a derailleur shift system, with 2 gears, the first for the maximal acceleration at the start, and another for optimal speed on the track:
This bike also was equipped with a TMM sensor to measure the influence of the derailleur system.
Nowadays many electric bicycles are available in the shops and over the internet in a large price range. To compare the performance of these bikes is very difficult for the customer.
In choosing a particular bike the dealer can help the buyer on bicycle related aspects, which bike type (racy, city, ATB, man or women model), specification (mudguards, type of gear system), weight and range of the bike etc, etc.
However it is very difficult for the consumer to judge the performance in a short test ride. Especially the inexperienced rider will not have a clue how to select the bike which fulfils his particular needs the best.
To help the buyer in selecting an electric bicycle the LEVA test standard is developed.
The LEVA test provides an objective test of the drive system, the result is presented in graphs and ratings which informs the rider of the character of the drive system. Ratings are given for flat road- , hill- and city (stop and go) riding. The ratings of the various bikes can easily be compared to make the optimal choice.
Please contact IDbike for information about prices and test possibilities.
What is tested
The drive system (motor-controller-sensor) of
Pedal assist bicycles (torque or speed sensor connected to the pedal crank)
Power on demand cycles (power is controlled with twist grip, no pedalling needed)
What is not tested
The battery specification, number of cycles to end of life, total capacity,
Bicycle related subjects which can be advised by the dealer:
The riding characteristics of the bike
The quality of the bicycle components
How is tested
All test bicycles are tested on a test rig which fulfils the standards (accuracy, approved transducers etc.)
Based on test criteria (listed hereunder) the road load forces for flat road riding, hill climb and city riding are calculated and set in the test machine when performing the tests.
Test rig according to test rig standard:
All cycles are loaded with the same rider: Weight 70 kg, frontal area and air resistance (Cd x A = 0.6) , tyre runs on a metal drum, the rolling resistance of the tires (0.006),
The load on the bikes is calculated, based on standardised conditions: pedalling action (sinusoidal with 30% amplitude)
Environmental temperature 18-22 °C
Flat road test: no wind
Hill climb test: climb angle 4%,
Tests is done in transmission ratio as close as possible to 6.6 m per pedal revolution. (~ 63 rpm at 25 km/hr)
Power is provided by an external switched power supply set at nominal battery value / or by the conditioned battery of the bike: fully charged at full capacity (t.b.d.)
The bicycle is mounted on a test rig. A servo drive motor simulates the fluctuating pedal power from the rider. The rear wheel is determining the speed. The propulsion power on the rear wheel is set to conform to the test conditions.
The LEVA test protocol consists of 3 parts:
Hill climb, constant speed
Acceleration test under constant torque
A mixed drive cycle consists of acceleration and stopping, riding at various levels of constant speed and a short stretch of hill climb. The test shows a result which is very comparable to everyday riding, shopping, etc. The test results are average support data and range in mixed riding with stop and go, hill climb and flat road riding
The Constant speed test
Shows results for hill climb with constant speed 18 km/hr
Acceleration test under constant torque
Measures time to reach 18 km/hr with a constant pedal torque of 50 Nm
The performance test parameters are measured continuously.
These parameters are:
Input power from the rider (torque & speed),
Input power from the power supply (Voltage and current),
Road load (Output power - drive force and speed)
The test data are recorded and analysed in a test report.
To estimate the range the nominal battery specification is used. Actual battery performance should be tested in separate battery test. Battery testing is a costly and time consuming affair that is not incorporated in the drive system test.
Constant speed test
In the constant speed test the energy consumption is measured continuously. Range is calculated by dividing the nominal battery capacity by the consumption at a certain speed , multiplied with this speed.
The watt-hour consumption is measured in the mixed cycle,
The cycle length is measured.
Range is calculated by calculating the number of cycles that can be done with the nominal battery capacity. Range is number of cycles x distance per cycle.
Test result presentation
City cycle: range and required cyclist input power
Continuous riding on hill climb: range, cyclist input power and speed
Acceleration test: time to reach 18 km/hr frorm standstill, under constant pedal torque of 50 Nm.
For Power On Demand the same method of testing can be employed but presentation will be simpler: max speed, hill climb speed are easily measured. Acceleration test is similar.
Test report provides
Constant speed result is presented in a graph, which shows maximum range and support in ideal conditions (constant speed)
City Cycle result: shows the performance of the drive systems under conditions which are comparable to real world riding. Test result is averaged support, support level during acceleration and range.
Ranges and performance are determined on nominal battery voltage and capacity.
IDbike offers high quality development capacity, to develop and improve products, especially electric bikes. Our developments are executed in close collaboration with our customers in the bicycle industry.
We perform complete developments, from idea generation to prototype construction and testing.
This project of IDbike started in 1993 and concerned a radical new design of a bike for attacking the world speed record. The main characteristic of this bike was the fact that the rider steered behind his back, in a position, which is comparable of that of speed skaters. To hold this strange, but aerodynamic position, the body of the rider was supported by a chest support, on whichthe rider could lean. After a prototype was build, the bike was tested on the road, and air resistance measurements were performed. The resistance turned out to be much lower than a conventional bike (-15%), with a rider in the so-called triathlon position.
Already the preparations for a world record attempt were in full swing, when the UCI regulations were changed, and the skate position was banned. Because of these changes the sponsors quitted the project, and the prototype AeroBike is a museum piece now.
The Bicycle CVT
Another project concerns the development of a CVT system for bicycles. IDbike has studied suitable Continuously Variable Transmission systems extensively, and has become an expert in this kind of technology. Ten years ago one of these systems, based on a friction drive with cone shaped rollers, was developed further, and a prototype was build. Test-drives of the system turned out to be very successful; the system shifts very easily, and the efficiency of the system is reasonable.
An electric bicycle is a bicycle with electric support. Especially in Europe and Japan the most successful electric bicycle is the version with proportional support. The power supplied by the electric system is proportional to the power supplied by the cyclist. This way the electric bicycle feels like an ordinary bicycle, but it rides much easier.
Already in 1998 IDbike has done extensive research towards developing the ideal electric bicycle. Marketing research has also been done also and an important conclusion was: An electric bicycle not only has to feel like an ordinary bicycle, but also has to look like one. Based on this conclusion, in the year 1999 IDbike started the development of a new generation of electric bicycles , with the following specifications:
An electric motor in the rear wheel.
Batteries integrated in the bicycle frame
The torque sensor as a modular part offers more freedom of design
This picture shows the initial prototype of the Ebow bicycle, which was developed for the Accell Group. This electric bicycle was equipped with a TMM version 1 sensor (Torque Measurement Method 1), for the measurement of the torque generated by the cyclist. The electronics were situated in a box in the middle of the frame and the bicycle was controlled from a unit on top of the main frame tube.
The first Ebow was manufactured by Sparta and presented to the public as the ION at the IFMA bicycle show in Cologne, September 2001.
The main changes over the prototypes were:
The motor electronics were situated in the motor
The TMM version 1 sensor was integrated with the motor
The capacity of the battery was improved
The frame was modified so the battery can be installed through the lower end of the main frame tube, for better accessibility and maintenance
The control unit was made smaller and situated on the handlebar
The motor electronics, the battery electronics and the control unit were connected using a BUS infrastructure.
IDbike also was a member of the development team of the Gazelle Innergy. The Innergy uses the TMM4 sensor, which is integrated in the rear drop out.
The display is the most visible component of an electric drivetrain. With the remote control the cyclist has the riding programs and all cycling data under his thumb. The backlight guarantees readability under all conditions. This LCD display is programmable; therefore, the layout can be tailored to OEM- requirements. With parametrised algorithms this display also functions as an interface for product managers to tune the riding programs according to their wishes.
Our displays receive information from the intelligent motor controller through a BUS connection, or wireless via Bluetooth. The displays feature identical connections and are thus interchangeable IDbike provides different software versions for the displays. With special factory software the parameters of the bike can be changed in a simple way:
Various displays are available:
A sophisticated display with LCD screen, showing speed, time, battery condition etc. (V3)
A simple LED display, controlling basic functions (V1)
A wireless LCD display via Bluetooth. (V4)
Apart from the standard available versions, customer specific display lay-out and info fields are possible. The display PCB is custom made to the housing and button configuration that is selected by the customer.
Specifications Display V3
128 x 100 pixels
46 x 36 mm. (width x height)
Transflective technology: perfect under all conditions
Programmable for logo's & multiple screens Tailor made for OEM-customers
Centre of handlebar
Remote Control Near handlebar grips (LH or RH) On/Off system
On/Off White Blue
LIN bus 3 lead wires
Stored inside V3.3 controller, display can be swapped
On/Off manually On/Off automatically
Complies with EN 15194:2017
Actual speed (in 0,5 km/h. or mph) Max speed Average speed Trip distance ODO Clock Stopwatch Riding program (2, 3 or 4 support ratios) Battery status (SOC) Light on/off Version / firmware Cyclist's torque & power Error codes
System switch (lower button) Light switch (centre button) Program change (upper & lower button) Screen data change (centre button) Second screen (centre button)
Product manager can change parameters & riding programs Data acquisition modus Graphically checking input sensor & current signals
The motor controller is a key component for E-bikes and Pedelecs. It processes sensor information and controls the power supplied to the motor (i.e. motor driving algorithms). In addition the controller handles the riding programs for the cyclist (i.e. riding algorithms). The riding programs can be tuned to the OEM's brand DNA. The new IDbike V3.3 controller is based on FOC technology (Field Oriented Control). With FOC we can control and drive motors with higher efficiency, less noise and more torque. Thanks to the double layered topology we were able to minimise the dimensions.
Very low RDS-on (3 mOhm) results in high efficiency
●Max DC current:
25 Amp, 60s
20 Amp, continuous
Limit can be set in software
< 50 uA (standby). On/off switch is not necessary.
●Torque Sensor input:
TMM / optional extra hand grip
Connected via LIN bus interface (12V/Data/Gnd)
3 types of display available, can be exchanged. (LED, segmented and matrix).
Also works without display.
Via LIN bus (separate usb-linbus interface available) or Bluetooth. Separate USB LIN-bus interface available.
Via LCD Display and/or setup files, or via Bluetooth
IDbike has a lot of experience with the development of the various components of bicycles, like handlebars, stems, seat posts and pedals. Some examples are:
1. The Aergo handlebar
Every cyclist has their optimal seating position to ensure a pleasant and comfortable ride. However, depending on the type of bike tour, the mood of the rider and even the weather situation, this position may change. When riding into the wind a forward position is best, at other times an upright position is preferred. From time to time, cyclists also need to be able to adjust their position, as easily as possible. Already various different adjustable stems are on the market, but these often require the use of tools for adjustment.
The Aergo adjustable handlebar solved a problem faced by many cyclists: their position on the bicycle never seems to be just right. With the Aergo handle-bar, the riding position of the rider can be adjusted during the bike ride, at the push of a button.For a comfortable ride... press the handgrip button and pull the Aergo back to create an upright position.
Need a aerodynamic position against a strong headwind? Push the Aergo handlebar forward. You can choose from 10 different positions for instant and optimal adjustment to the specific situation.
The working principle
The core of the Aergo consists of a patented synchronizing system, which also functions as the bearing system of both halves of the handlebar. This system is self lubricating and has a pre-tension system, ensuring lasting play-free operation.The locking system is controlled by a push button on the grip, or a twist-grip. The locking mechanism is actuated through the handlebar tube, guaranteeing a long and trouble free operation, as it cannot be damaged by external forces.The mechanism is completely encapsulated by the housing, shaped into unity with the handlebar and steering pin.
IDbike recently has developed a new model of the Aergo handlebar. This model has a grip shift control to activate the handlebar adjustment. Added is further an adjustable stem with which the bicylist can adjust the handlebar to his needs.
Also the handlebar has been redesigned completely:
2. The Recline stem
3. The Simple stem
With only one bolt both stem inclination and handle bar position can be adjusted.