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E-Bike Testing


I test my electric bicycles on 
	a 3.0 km hill climb
	a 3.5 km street circuit and
	a 1.25km length of street (the top part of the circuit - each way)

The hill climb is a closed 3 km of bypassed road used by sports car enthusiasts for regular hill climb events.
It is used for training by serious cyclists, is a good workout for a fit cyclist, and is hard going for a 
more typical bike rider, and so is a good test of ability of an e-bike to climb all but the steepest hills
in any built up area. Most of my e-bikes will take me (78kg) up there without pedalling 
as fast or faster than I can do on a road bike, and a little faster again when I do some pedalling ahead of the motor. 
Location : Gyndier Rd, Tewantin. From gate to gate - 3km.

The point to note is that while a 1000 watt (ie more than a horse) hub motor will take you up just about any hill,
so will the less powerful motors IF..
you do enough pedaling to keep the motor in its effecient range (ie not struggling) - about a running pace 15kmh. 
Just off the map above is Mt Tinbeerwah. The road up there is the steepest around here.
I got up there on the #13 folding bike with 2 gears to spare. The steepest hill in town is the hill
between Noosa Main Beach and Noosa Junction. The #13 folding bike got me up there with 3 gears to spare.  

The street circuit is 3.5 km with one medium hill, a smaller one (shown as red up and green down) and
gentle undulations (shown blue), with several corners usually not requiring a need to stop. 
Location : Griffiths Ave, Cooroy Rd, Carramar St and Golfcourse Rd in Tewantin.

I test the bikes either without any pedalling, or with normal pedalling.
Testing wthout any pedalling gives a direct comparison between bikes. 
You will do better if you do some pedaling and get ahead of the motor.
Testing while doing normal pedalling is a less direct comparison as you may add more or less effort than I,
but it's a realistic average for a reasonably fit person not using full power, except on the hills.
That's what I recommend - do your normal pedaling with as little or as much assistance you need.

I've found that where I would be averaging about 18-20 without the motor I average about 25-7 on the alloy 
folding bikes and about 30-35 on an Ezi-go 500w conversion.  

Distance between charges testing is done either by repeatedly doing the street circuit, or by normal travel.
The tests are done at a little less than maximum speed (for better efficiency) and without pedaling.   

Maximum power versus maximum speed
More power does not give proportionally higher maximum speed but it 
does mean more speed going uphill.
Just as with a car's motor in any gear there is a speed range where the motor performs most efficiently
while at much lower or higher speeds the motor will either struggle or max out. Electric motors have
various performances, as fuelled motors do.

As you travel the three main forces you have to overcome are wind resistance, rolling resistance and gravity. 
The first varies with (approx) the square of your speed, and the others vary with the speed.
You can estimate the wind + rolling resistance at any speed as the downhill gradient
at which you can just maintain that steady speed.
You can work out approximately how much power you need for a hill :
Watts = weight (kg) x speed (M/sec) x 9.81 x gradient (%)
or 100kg at 20kmh at 4% (3% hill + 1% w+r) = 218W
100kg at 28kmh at 5.5% (3.5% hill + 2% w+r) = 420W
That is approximately what you can expect from 200w and 400w motors.

AN INVITATION: If anyone who sells or has any electric bike and is willing to lend it to me,
I will test it on the same circuits and report here the results. So far as I know noone is
making any comparisons on standard test for e-bikes like the motoring magazines do for cars.

Bikes tested :
Bike/kit model nominal power maximum street circuit hill climb

Watts kmh high medium low high medium
Alloy E-bike 13 (Happy Feet - 2012) motor alone 250 26.5 26.1 22.7 18.1 25.4 22.4 21.9
Alloy E-bike 13 (Happy Feet - current 2013 model) motor alone 250 28.7 28.7 ? ? 28 ? 23.5
Big Red# motor alone 250 31.4 31.4 26.5 19.5 29.8
23.3
Big Red# + pedaling * 250 32.6 32.6 31
28.8
250 Watt Ezi-go conversion 26"wheel motor alone 250 26 25.9

25.4
21.7
500 Watt Ezi-go conversion 26" wheel motor alone 500





28.9
500 Watt Golden Motor conversion 26" wheel motor alone 500
32.1

30.7
27.7

# The Big Red off road version
* Pedaling - to add enough speed to keep motor running efficiently