LEVA test
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 criteria
- 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:
- City Cycle
- Hill climb, constant speed
- Acceleration test under constant torque
City Cycle
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.
Range calculation
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.
City cycle
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.
