How accurate are distances on e bikes

[PCeBiker]

I wanted to have a reasonably accurate speedometer because the speed limit in Canada is 32 kph.
Anything faster and I'm risking $5000 in fines.

I use my odometer/trip meter along with my voltmeter to guesstimate how far I can go on a charge.
It's somewhere between 58 km and 85 km depending on all kinds of factors (especially speed and wind).

I know that I can comfortably go at least 58 km, but I just can't seem to get over my range anxiety.

I wish I could turn off all the displays and information and just ride my ebike like how I rode my bicycle when I was a kid.
I didn't know or care how far or fast I was going.

 

[Ben J]

A few people mentioned adjusting wheel circumference to dial in the speedometer on the bike. That's getting locked down more and more because it was used as an exploit to exceed the bike's speed limit.

I wanted to have a reasonably accurate speedometer because the speed limit in Canada is 32 kph.

Speed limits on ebikes refer to the maximum speed where the bike is allowed to provide assist. It's okay if the bike goes faster than that as long as the part over 32kph is human power or gravity power.

 

[mrgold35]

A few people mentioned adjusting wheel circumference to dial in the speedometer on the bike. That's getting locked down more and more because it was used as an exploit to exceed the bike's speed limit.

I could adjust the wheel circumference on my 2016 Radrover. Just purchased a 4.8" fat tire Himiway Cobra Pro and noticed the exact same issue of the controller being set to 26" and the fat tire is closer to 28"/29" in circumference. I can't change the wheel diameter in the Himiway controller and my speedo (and odo) is off again by 1-2 mph on the low side compared to radar signs and the wife's Radcity.

 

[PCeBiker]

I tried adjusting the wheel circumference on my display and controller too, and it didn't work.

All it did was change the speedometer reading, but my actual speed Would NOT go over 32 kph.

I don't know how it works because I could have bought the controller and display for an e-bike with 20" wheels.

The only thing that I can think of is that I had originally entered 29" wheel diameter and maybe after a certain amount of time or distance, that setting becomes locked?

I should have set it to a 5" wheel when I first got it, then maybe I could actually go 72 kph?

 

[PCeBiker]

It's okay if the bike goes faster than that as long as the part over 32kph is human power or gravity power.

With my controller and display, the moment I hit 32 kph the power cuts off completely, so All the power to go faster comes from me pedaling.

Some setups leave the power on at the maximum 500 Watts and you provide the power for the speed over 32 kph.

That's how Das-Kit used to function but they were forced to comply with Canadian law and now the power cuts off completely at 32 kph.

 

[Shifty Shane]

I appreciate that the distance travelled is not too accurate, but just how accurate or not is the distance travelled as shown on the e bike screen

Thanks

With my wheel diameter set to 29" (actual is 28.8"), my speedometer and odometer are approximately 97% accurate compared to a GPS speed app on my tablet and also my phone.
For the most accurate wheel diameter selection, you need to measure your rear tire's actual circumference in inches, then divide that value by 3.14159 to get the correct wheel diameter for the most accurate speedometer calibration.
Lay out a tape measure up to approximately 100", then rotate your rear tire until the valve stem is directly at the bottom (6'Oclock position), align the tape measure end with the valve stem, then sit on your bike (tire deflection from your weight will affect the diameter slightly) now roll forward one full revolution, until the rear tire valve stem is back at 6'Oclock, and note the corresponding value in inches on the tape measure. My 27.5" x 3" tires circumference measured 90.5" which calculated to 28.8" diameter.

 

[Shifty Shane]

With my controller and display, the moment I hit 32 kph the power cuts off completely, so All the power to go faster comes from me pedaling.

Some setups leave the power on at the maximum 500 Watts and you provide the power for the speed over 32 kph.

That's how Das-Kit used to function but they were forced to comply with Canadian law and now the power cuts off completely at 32 kph.

In your controller programming settings, on the "Basic page" where you set the wheel diameter, try changing "SpdMeter Signal" (# of speed sensors) from 1 to 2. That should trick the software into calculating 2 wheel rotations as a single wheel rotation, which will trick it into interpreting the calculated speed as 1/2 of the actual speed. Your speedometer will likely be reading 50% of actual speed as well, but you should be able to have assist up to 64km/h.
I ordered my bike and selected "off road use only" vs 20 or 32 km/h speed limit. The display speed limit came set to 90km/h and the only speed limit in the software was on the "Throttle page" where speed limited was set to 40km/h for the throttle only. All the assist levels speed % were 100% and the pedal assist speed limited was set to "by displays command", so the display speed limit has priority for pedal assist. I set my wheel diameter correctly in the display and software by measuring the actual distance travelled from one tire revolution (wheel circumference 90.5") then dividing the result by 3.14159 to get the wheel diameter of 28.8" (set to 29" in display and software). I changed the "Throttle page" speed limited to "by displays command" and set the display speed limit to 72km/h. I am able to get up to 60-65km/h on flat roads and nearly 75km/h on short downhill descents where the pedal assist and throttle assist remain active.