Electric Bike Test Lab

Why am I testing electric bikes?

I purchased an ebike in December of 2017. This ebike was listed as a class 3 and the manufacturer stated that the top speed was 28 mph. I should have test ridden the ebike but I trusted the manufacturer’s website. However, once I had it at home, I quickly discovered that it would only assist to 25 or so. I know, 3 mph is not a big deal but I felt cheated. In addition, some issues arose regarding the battery mounting that was never discussed in the review. For over 18 months now I’ve ridden this ebike as much as I can and do enjoy it greatly. And the dealer has been wonderful so my experience wasn’t all that bad…

However, my experience could have been better with access to actual data about how it performed. With my testing, I intend to provide that data to others so they can make informed decisions regarding their ebike purchase. Knowing the true range at a given speed would have been extremely helpful!

Why should you trust my data and reviews?

As a mechanical engineer who has been involved with vehicle testing for more than 12 years, I know my way around instrumentation, testing, and post test data analysis. The 20 Hz GPS unit I use is trusted in the industry. The power pedals utilized are accurate to 1%. The range estimations are based on real world power vs. speed requirements. Lastly, all of my test methods are published right here for anyone to review or critique. I’m also open to suggestions and additions so please let me know if you have any.

Ebike Setup and Instrumentation

Each Ebike is setup with all of it’s factory supplied equipment such as fenders, rack, lights, and factory pedals. The total weight is measured with and without the battery or batteries using a calibrated scale. The computer settings, if any, are left at their factory default level unless noted in the test report. The tire pressures are set to the recommended pressure in the owner’s manual, or to the middle of the sidewall listed range if there is no recommended pressure stated in the owner’s manual.
The factory pedals are then removed and power meter pedals are installed. A Garmin Edge cycling computer and Vbox GPS unit are installed on the handlebars. The weight is measured again with the installed instrumentation. The rider weight with helmet is also measured and noted in the test report. I’m a big guy (6′ 3″ and 190 lbs) so my target weight for rider, helmet, instrumentation, and water bottle with cage is 200 lbs. I adjust the water bottle or bottles to reach that target for every test, unless noted separately. For the durability and real world range testing, I may also add a pannier bag or backpack with laptop that adds another 10 lbs for a total additional weight of 210. This will all be noted in the test report for each individual bike.

Acceleration

After initial setup and instrumentation, the battery is checked to make sure it is charged to 100% and battery voltage is recorded. The ebike is then ridden on zero assist to a nearby flat stretch of asphalt paved rail trail. There, it undergoes acceleration testing, where several are made for each acceleration type (throttle, zero effort pedaling, 100 watt pedaling, 200 watt pedaling) with an even number of runs performed in each direction.


For the throttle only accelerations, the throttle is placed at maximum from a dead start and the ebike is allowed to reach it’s maximum throttle assisted speed. If the ebike has a cadence sensor, acceleration to maximum assisted speed is also measured while spinning with zero load and the PAS set to max. If the ebike has a torque sensor, acceleration is measured while pedaling as lightly as possible.


Acceleration is also measured while averaging 100 watts of pedaling at an average cadence of 80 rpm, and then finally with an average 200 watts of pedaling at an average cadence of 80 rpm. Results are calculated from the 20 Hz GPS unit and the power pedals. The acceleration times for each are reported as a single average along with the average power and cadence as appropriate. Runs are repeated as necessary to achieve the desired power and cadence. Shifting is performed as needed to meet the target power and cadence.

Braking

Once the acceleration tests have been completed, the braking distance tests are performed on the same flat stretch of asphalt paved rail trail. The ebike is acceleration to it’s maximum assisted speed. Once the front wheel crosses a line marked on the pavement, both brakes are applied to their maximum level. In many cases, the rear wheel will lift off of the ground. Once stopped, the distance from the line to the bottom of the front wheel are measured and recorded. This is repeated as many as needed to have at least 3 stops in each direction without any major outliers.


Now, I understand that rider skill has a lot to do with braking distances. However, braking distances can vary due to tire compound, type of brakes, and road surface. Brake tests are only performed when the asphalt surface is clean, dry, and the surface temperature is between 50 and 80 degrees F. Due to the variability in these tests, they should serve as only a guideline but it helps to understand how quickly a certain ebike can be brought to a stop.

Road Load and Calculated Range

Once the brake tests are completed, the road load tests are completed. The purpose of the road load test is to determine the power necessary to propel the ebike at various steady state speeds over a flat section of smooth asphalt. To do this, the assist is set to zero, or off, and ebike is pedaled at a steady speed over a flat section of asphalt in both directions. Typically, the ebike is pedaled at 5 mph in both directions, then 10, then 15, then, 20, then 25, and then finally, the top assisted speed, which is typically 28 mph. Several repeat runs are made to assure statistically significant data (I know that varies by statistician, I use a t-test of 95% or greater confidence for significance).


Once the data is collected, the average pedal power is calculated for each speed. Efficiencies are then taken into account so losses from the battery through the controller and motor can be calculated. Finally, a battery wattage per speed chart can be made. Using the manufacturer’s published battery and amp-hour figures, one can then calculate the range for any given speed (for flat ground of course).

Hill Climb Performance

Ideally, we would have access to a set of constant grade hills, such as those built at an automotive proving grounds. Lacking a set of these, the hill climb performance is measured on a particularly long uphill road, Ice Pond Road. Starting near Route 312 in Brewster, NY, Ice Pond Road then climbs 325 feet in exactly one mile. The grade averages 6% but portions are as steep as 25%. This is a segment on Strava as well, simply search for “Ice Pond Rd” in Brewster, NY.


After confirming that the battery is fully charged and the voltage recorded, the ebike is started from a marked spot near Route 312. For the throttle only climb, no pedaling is performed. The time to reach the top of hill is recorded or, if it can’t reach the top of the hill, the total distance traveled is noted. If the ebike does not have a throttle, this first test is performed with no pedaling effort applied, simply spinning along to activate the cadence sensor. For bikes with torque and cadence, this test is usually skipped. The hill climb is then repeated with pedaling an average of 100 watts at 80 rpm (or lower if gearing requires it). The actual pedal power will be reported for each result.


These tests serve as a good measure how well each ebike climbs. Some ebikes are simply better climbers due to their motor type and maximum power output.

Real World Range Evaluation

There are two styles of real world range tests that can be performed. In both cases, the battery is charged to 100% and the voltage is recorded at the beginning. For the first test, the ebike is ridden on max assist on the Putnam and North County trails from the test lab to White Plains Road, a distance of 36 miles while the rider contributes an average of 100 to 150 watts or so. The voltage is then recorded at the end if the low voltage cutout isn’t triggered. If the low voltage cutout is triggered, the total distance traveled is recorded. The average speed, pedal power, starting and ending voltages are recorded and reported. These results will all be noted in the test report.


The second style of real world range testing involves riding around a closed loop set of roads at various locations until the low voltage cutout is reached, again while averaging 100 to 150 watts of pedaling. In this instance, the ebike will continue until the low voltage cutout is triggered. The average speed, pedal power, starting and ending voltages are recorded and reported.

Thanks for making it to the end of this ling post!
Jason Holmes
 
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harryS

Well-Known Member
I read your testing methods. You install torque sensing pedals? Seems thorough.

Hope you get some local owners that wanna see how their bikes stack up.
 
I read your testing methods. You install torque sensing pedals? Seems thorough.

Hope you get some local owners that wanna see how their bikes stack up.
Thanks! I do install power pedals. After some thorough research, I went with the Favero Assioma Duo’s. They have a claimed accuracy of 1% and I do a zero calibration before each test and again before the road load portion of the test. They have been great so far.

I’m hoping to partner with some local ebike shops that rent as well. With any luck, I’ll add a bike to the test list every week or so.
 
I've now completed most of the testing on a Faraday Cortland! It was fun to evaluate my daughter's bike with me and her riding it. I still need to do some more testing with it, so results will be updated.

Oh and I updated the Metro+ results with hill climb information. It's quite the climber!