Introduction

Riding an electric bike has all the freedoms of riding a normal push bike and with less effort but with increased costs and weight. A to B magazine lists a few more arguments. Some newspapers have noticed the new electric bicycle phenomenom and given it their support. Never think of a little electric power assistance as cheating versus a normal bike, instead, it lets even a beginner cyclist replace a big costly car for normal commuting. China is full of millions of electric bikes but many are really electric motorbikes which are a bit more dangerous. If you have ever lived in Thailand or Vietnam, you would have been amazed at how much more convenient a motorbike is than a car for trips around town. I have been eating dinners where the host has realised there was a missing ingredient or the beer had run out and twice nipped to a shop and back in under two minutes. This is not possible with a car because because of distances, parking and congestion which never affect a two wheeler and shop locations adjust accordingly.

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Cycling Advantages

Cyclists are the happiest commuters because they suffer no congestion, no parking charges, no parking problems and get free endorphins and free healthy exercise. Bicycles are clean, cheap, healthy, sociable and efficient. Congestion and traffic lights remove any potential speed advantage of cars and motor bikes on city commutes. It is amazing how little motorists notice how much they are wasting their lives getting fat and angry inside cars stuck at traffic jams earning money to buy cars, and to pay for insurance, repairs, lost interest on their investment, taxes and also a little on non-renewable fuel. Even in the United States of America, things may be changing to help cyclists. Bicycles are the most efficient form of personal transport: both cooler and faster than walking or running and more efficient than any other personal vehicle (like a car) and cheaper and more flexible than any public transport because trains need expensive active rail tracks and points, stop running late at night and are crowded with sneezers all Winter. Some people cycle for sport or exercise and so may want showers but cycling is more efficient than walking so uses less energy and has more breeze cooling than walking so has less actual need for showering than even walkers do (especially where there are few hills and if the cyclist has enough time to slow down for a few Km before stopping).

However, bicycles are not aerodynamic and drag rises with the square of the velocity so a cyclist going 50 Km/h needs to generate around 4 times the power of one traveling at 25 Km/h. Normal bicycles will never be quick but aerodynamic ones have been pedalled over 1000 Km in 24 hours by a single rider but faired recumbents will never be as convenient as a normal bike and hills cause special problems too so very aerodynamic HPVs are not going to appeal to most people no matter how expensive petroleum becomes. Instead, there is another way to boost the bicycle to speeds higher than normal city traffic (<20 Km/h) and to keep the health and social benefits of cycling (no one can see you in a car) - just add a little electric boost motor.

Electric Bike Advantages

The main advantage of an electric bike is help on the hills and into nasty headwinds. All the other problems of cycling remain but that little bit of electric help means that many people who have not been cycling for ages are now able to start slowly getting fit again and do even less work than a normal cyclist so always arrive cool and non-sweaty regardless of all conditions. A perfect electric bike would also be able to increase the average cycling speed.

Electric Bike Technology

Across Europe all electric bikes should be the same soon because they may all be defined by the same law - even in Britain. (This law is Europe at its best creating common markets and sensible standardisation). The law says amongst other things that the bicycles must have pedals, must not provide power above 25 Km/hour and should have a continuous rated output below 250 Watts.

Motors

There is no perfect electric bike on the market yet though some are getting close. Most electric bikes fall into two groups: Crank motor or hub motor. The crank motor puts power through the gears so has the advantage of an efficient freewheel and a large even power band from steep hills up to level ground but has the disadvantage of measuring force through torque which means that power pulses from your pedals are amplified on the bike and weak riders get less help than strong ones which is wrong. The other problems of crank motors (like Panasonic's) are that the frame needs to be customised, the clutches and freewheels are complex (heavy and customised) and the top speed specified in law is measured from the motor so pedalling cadence needs to be reduced or the motor reduces power or cuts out altogether. Also, the efficient freewheel means that there is no potential for regenerative braking (which is pretty limited without hills). The classic example of a well-made bike with a crank motor is the Kalkhoff Agattu. The power reduction and cut-offs for an Agattu start at only 15 Km/h in any gear and the total cut-off at 14 Km/h if you are in 1st gear so, despite the extra weight and expense, a strong normal cyclist on a flat route will be faster than an electric-assisted Kalkhoff Panasonic hub drive bike.

From the Kalkhoff manual:

Power assistance is not available if:
- The pedalling power is too weak
- The battery light is blinking
- when riding at more than 24 km/h in 7th gear
- when riding at more than 18 km/h in 4th gear
- when riding at more than 14 km/h in 1st gear
Graph showing Panasonic motor power reductions in top gear

A hub motor bike is directly connected to the wheel so needs gearing to reduce the high-spinning motor down to the speed of the slow spinning wheel climbing a nasty hill. This gearing can make noisy but the Tongxin motor and BionX motors are reputed to be almost silent. The Sanyo Eneloop bike has a geared hub motor with a 1 to 2 power ratio. The BionX hub motor is the classic hub motor with clever electronic controls offering high power, efficiency and regenerative braking. With all the custom components located in a hub, standard bike frames can be used so well-established favourites like Brompton folding bikes and normal mountain bikes can be customised.

Batteries

Only a few kinds of battery should be considered for electric bikes currently: Lithium polymer, Lithium Iron Phosphate, and Lithium Manganese though the specific chemistries and constructions are merging and mixing. The latest battery news shows 10000 charges or more for lithium batteries. More exotic Lithium metal, or Lithium Silicon, or Lithium Sulphide batteries should be available within two years. Lithium Iron Phosphate is ideal for stability over temperatures and charge cycles (> 2000) and is currently available in high power (A123 offers over 60 Amps from a 2.3 Amp hour cell) or low cost (ThunderSky <400 Euros per KW-hour) chemistries . Lithium polymer needs much more care and can burst into flames with a bit of damage. Lithium Manganese is both high capacity and is more stable than normal "Lithium Ion" batteries (made with Cobolt Oxide) plus it can be recharged over 500 times if properly managed.

All batteries can be damaged by improper use. Lithium batteries are very easy to damage if they get too hot, too cold, punctured, overcharged or flattened. Sometimes, they even burst into flames and burn down your house so be careful - well the old ones could but that is much less likely with the newer chemistries. So, for safety, and longevity, the electric bike needs a good charger and a careful battery management system when running. Each cell in a battery needs to be monitored as it charges and when in use. This absolutely requires awkward wires to every cell with completely reliable computers and power control electronics. Kalkhoff Lithium Manganese batteries come with a two-year warranty and seem to be very reliable in practice with very little capacity loss over 1-year.

Other battery chemistries

Nickel Metal Hydride(NiMh) batteries have a good reputation, are cheap and are not as fragile as Lithium batteries but they have low charging efficiency (losing about one third of the energy put-in) and cannot be discharged as quickly as poisonous Nickel Cadmium or high-power lithium chemistries. Also older (most common) NiMh batteries gradually lose their charge. After a bit of misuse many old NiMh batteries could lose most of their charge in a few weeks. Newer NiMh batteries are called "ready for use" or hybrid batteries and use a new electrical separator to reduce charge leakage. Newer NiMh batteries have names like: Hybrio, Eneloop, or Annsman MaxE but are not yet available in tagged cells for making into packs for bikes. Nickel Zinc batteries are very new and should be cheap and may be worth considering but reliability in electric bikes is not known yet. Maybe even a super pure capacitor insulator can obviate the need for chemical batteries ?

Personal Favourite

So my perspective is that The Tesla roadster car accelerates from 0 to over 120 Km/hour in less than four seconds using a single gear, with high efficiency, and carries on to around 200 Km/h but yet there is no street-legal electric bike that will go from 0 to just 25 Km/h and still significantly help on a 30% gradient - my hill. If a Tesla was 100 times the weight and 10 times faster than an e-bike, then building the e-bike might be 1000 times easier or cheaper - well maybe? The people who most need electric bikes are weaker folk who are not feeling very fit and anyone faced with fierce hills. Kalkhoff and Sparta bikes are tough, all-weather-capable and reliable so building the bike part is no problem. The batteries are easily good enough for any standard commute < 50 Km and well managed, they can last for 5+ years. All we need now, is a manufacturer who can produce a quiet motor and electronics that climbs hills like a goat and does not stop applying power when it gets faster than 14 Kh/h. I understand that the law does not say exactly how steeply the power must drop before 25Km/h, only that it must be reduced gradually and that the 250 Watts is sustained applied power after losses. If a weak cyclist dials in strong assistance, then it should be available to almost 25 Km/h so anyone can dispose of their car, save the environment and get to work quickly, safely and happily. The electric bike industry has recently asked for higher power bikes to be the new legal standard. Cycling through the steeply rolling Chiltern hills would make even 50% regeneration efficiency very welcome and save on brake and wheel wear. If one lived somewhere with mountains, regeneration would make beautiful exciting rides open to everyone. I am not the natural electric bike customer but I would buy one of these all-gradients, all-legal-speeds all-weather bikes even if only to ship my friends around when the fuel protests start again. I should test the BionX special high torque motor to see if it already answers my needs ? How hard can it be ?

Review and Experimenters Links

Cycling Problems

To keep this balanced and fair, here are a list of the problems faced by all cyclists.



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