Who killed the electric bike !

Australia's legislation till very recently mandated a 200watts maximum power for electric bikes. This was among the most conservative power level in the world and has held back the practical usage of this means of transport for many people.
Only in late 2012 has the federal government relented on this legislation to allow the definition for an assisted bicycles with up to 250watts continuous power. 250Watts power is now at least common with a number of European countries enabling some imported E-bikes models to be sold and used but is still quite low.
Also while some state governments have updated their road rules to allow the 250 watt bikes - other states are yet to implement the recommendation in their road rules. [ref 1]

Below is a table to give people some idea of the power required to overcome gravity when going up hill on an E-Bike.
This example assumes a total weight of 100Kg for example a person of 70Kg a bike weighing 20kg + luggage 10kg. The speed is 7 Kmph to maintain stability of the rider - lower speeds can result in instability.
This does not include other losses for example wind resistance, electric motor inefficiency or rolling resistance so this represents the best case scenario - you actually need this much power as a bare minimum.

km/h
kg
click to up update table.

Power to go up a slope
angle of slope horizontal (m/s) altitude (m/s) power (watts)

If one encounters moderate slopes 200 watts is not sufficient unless you are able to pedal to supplement the motor, many people will encounter slopes requiring 300 watts or more to maintain a stable speed of 7 km/h, a heavier person will require even more power, a lighter combined weight would be able to go a bit faster.

An electric motor rated at 200watts maximum will usually be incapable of producing full power at low speeds (it may be only able to produce a small fraction of this) [ref 2] so it would seem that even a motor with a peak power of 500 to 750 watts would not be unreasonable to ask for in the case of anyone with very limited pedalling ability.
In the case of someone after a low cost means to get around without having to sweat on the hills and therefore require a change room and showers it is clear that 200watts is insufficient, of course the need to also wear a helmet under present rules forces further inconvenience and discomfort even for the shortest of ride.

The law should be changed to permit electric assisted bicycles with a mechanical output power up to 500watts at speeds below 25kmph.

A motor with a 750 watt peak rating rating may be required to produce a continuous 500watts mechanical output at lower speeds power thru the speed range from 0 up to 25kmph or 30Kmh where it would cut out- the purpose of the cut out is that the speed is limited and therefore the vehicle is still considered a bicycle and not a motor vehicle requiring registration.

How safe are E-bikes

E bikes assist motors cut out at 25kmph so they have no upper limit speed advantage over a normal bike. With speed cut-out at 25kmph they may maintain a similar speed on the flat to a normal bike. Going up hills or into a head wind they can do a higher speed with greatly reduced effort but the uphill speed will still be far less than on flat ground for example to reach 21Kmph on a 10% incline would require 570watts of power. Down hills they go no faster than other bikes can as the motor cuts out above 25kmph.
Some E bikes can take advantage of a regenerative breaking recharge the battery when breaking and helping to slow the bicycle down.
E-bike's designed to take advantage of regenerative breaking are able to increase their overall range.
They are a little heavier than traditional bicycles as the motor, transmission and battery system add around 8kg to the weight of a bicycle. For example the Dahon "Vitesse" folding bicycle with no electric assist weighs 11.8kg. While the similar sized Dahon "Boost" electrically assisted folding bike weights 19.6Kg [ref 3] .

If your wondering how the power table above is determined.
The Power formula used is based on Potential Energy investment per second: PE = m x g x h Where
Mass(m) = 100 kg
Acceleration of Gravity(g) = m/s2 (usually 9.8 on earth)
Height(h) = meters ( grade of slope * horizontal speed in Meters per second)
Potential Energy(PE) = Joules ( watts is just joules per second)

E bikes for utility cycling

You may find this quote from Wikipedia sounds familiar.

Negative marketing of utility cycling

" Various interests may wish to portray a negative image of utility cycling on public roads for various reasons. Some governments, wishing to promote private car use, have organised and funded publicity designed to discourage road cycling. Official road safety organisations have been accused of distributing literature that emphasises the danger of cycling on roads while failing to address attitudinal issues among the drivers of motor vehicles who are the main source of road danger.[18][19][20] Some road safety authorities have been accused of having a deliberate policy of discouraging cycling as a means of reducing bicyclist casualty statistics @quot;

reference wikipedia Utility_cycling negative marketing

Cheltenham Cyclist - Government helmet campaign could frighten cyclists off the road


Reference list

1. Marilyn Johnson . (14 November 2012). Electric bikes at 250 watts. the view has opened up nicely
Retrieved from http://www.monash.edu.au/news/show/electric-bikes-at-250-watts-the-view-has-opened-up-nicely

2. MIT 1999 Center for Innovation in Product Development . (2013). Understanding D.C. Motor Characteristics
Retrieved from http://lancet.mit.edu/motors/motors3.html#powercurve

3. Dahon . (2013). Products
Retrieved from http://www.dahon.com/products


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