Anatomy of an Electric Bike
Although electric bicycles are fundamentally very simple machines, if you are planning to use one for serious transport, its important to make sure the machine you choose will fit the bill. As always, you do get what you pay for!
Schwinn World GSE
Ezee Torq
All electric bicycles have three fundamental components: an electric motor, a battery, and an electronic speed controller. Let’s look at each of them in turn:
The electric motors may be mounted in the hub of one of the wheels, or drive the chain as a normal rider would. The hub mounted motor is direct drive and simply replaces one of the existing wheels. They barely change the appearance of the bicycle and are very efficient, but have no gearing. The chain drive unit drives through the bicycles gears which offers improved hill climbing ability and may be a great choice for hilly areas. The Australian made “Elation” is a great example of a chain drive unit. In practice however the hub motor certainly works and offers a lot help in climbing a hill, though it may not do all the work for you.
The motors themselves are either brushed or brushless. The brushed motors have been around since Edison’s days, and use metal brushes wiping a mechanical commutator to switch the electrical energy to the right part of the motor at the right time. These motors can work well, but will need attention from time to time.
Brushless DC motors (BLDC) use a more complex electronic controller to switch the electrical energy where it is needed. They don’t have parts rubbing each other, so they have a very long life. Also modern controllers generally have lower losses than brushes they replace, which mean there is more power available at the wheels, and less battery drain.
Finally some motors have a free wheeling clutch, meaning that the wheel spins freely when the motor is not used. This may be important if the bicycle is to the ridden frequently without electric assistance, since the motor’s rotor does have a fair bit of resistance when it’s not turning. If you always plan to get the motor’s help, it does not matter.
The battery will probably make the single biggest difference between a useful machine and a novel toy. Batteries come in three main varieties – Sealed Lead Acid (SLA), Nickel Metal Hydride (NiMh), and Lithium Ion or Lithium Polymer (Li or LiPo).
Early electric vehicles tended to use SLA batteries, which are the heaviest of all battery types for a given capacity. These batteries are similar in chemistry to a conventional car battery. Their life time is usually the smallest of the three types, meaning they will need replacement soonest. Also they don’t really like being charged rapidly, so charging usually takes place overnight. This type of battery was used in the original General Motors EV1 electric cars. SLA’s usually have the lowest purchase price.
NiMh batteries became very popular for portable electric power tools, and typically offer double the capacity to weight ratio than SLA types. Figures on their lifetimes vary, but they tend to last longer than SLA batteries given the same usage. The Toyota Prius Hybrid car uses NiMh batteries.
Li or LiPo batteries are generally offered in laptop computers due to their very high capacity/weight ratio. They typically offer triple the capacity to weight ratio of an SLA battery. These are currently the most expensive of all the battery types on offer, but do make the bicycle least cumbersome. Generally these are advertised as “Near Life Time” batteries, implying they never die, although this really remains to be seen.
Some form of electronic controller is required to allow the rider to control how much assistance the motor will give him (or her). This is usually controlled by a throttle like arrangement mounted on the handlebars of the bicycle.
Early electric bikes had unreliable speed controllers; however modern units don’t seem to fail often. Also early units tended to be inefficient, meaning they wasted a fair bit of the batteries precious power in heat, but modern units run cool, and deliver most of the power to the wheels.
What Bikes were used on the ride?
Leading USA Bicycle Manufacturer Schwinn has very given Steve their latest World GSE Electric Bicycle to ride. These units have not even been formally released yet, and are bound to take the world by storm.
It has been designed from the ground up, and has a remarkably light drive train fitted to an alloy/composite frame. The drive train including battery weighs a tiny 4.6Kg! The Schwinn battery is made from Lithium Polymer materials. Schwinn claim it is the lightest and most durable on the market.
While the bike can give a staggering 65 km range, we will be going roughly twice this distance most days. Schwinn have kindly lent Steve spare batteries, which he recharged overnight from a conventional AC power supply. These batteries simply slide in place under the carrier.
When Steve decided to invite his friends to join him, he realised he would need more bikes. Go Electric’s Richard Poutney came to the rescue at vary short notice and helped us out by supplying 14 Ezee Torq bikes at well under cost price. Without his help Steve would have had a very lonely ride. These bikes are also a work of art in their own right, and served our riders well. These bikes are larger and heavier than the Schwinns, however they have amazing torque as the name suggests, which provided phenomenal hill climbing ability. On these bikes the seat flips out of the way, and the battery slides out.
Both bikes come with our strongest recommendations.