Electric Bicycles

Introduction

My roommate just bought one on 2008-04-19, a low cost 250 watt 36 volt Jinhua Luyuan Electric model from GWEV (Green World Electric Vehicles), similar to the one in the picture. Most models are twice as powerful. Of course, I got to ride it. Click the camera icon for a larger image.

What It Is Like To Ride One

Downside

• The biggest downside is the difficulty maneuvering the bike indoors. It is heavy and if you get it even a little off balance, there is no way you can hold it from falling over. I once made the mistake of trying to take it down some cement stairs. I quickly found myself unable to control the bike and was soon stuck pinned under it until a passeryby rescued me. The reason I have the bike is my room mate found it too unweildy to maneuver and I inherited it.
• After six years the battery is losing its ability to hold a full charge. I must recharge after every trip, or I end up pedalling without electric assist, an onerous task given the weight of the bike. However, I cannot find any place that stocks a replacement battery. The original dealer has gone out of business.

Bad Weather Use

Specifications

The bike has a rated range of 30 km (18.64 miles) More expensive models are in the range of 80 km (49.71 miles). I would expect it depends just how much you use the assist. You plug the bike into the wall to charge any time it is not in use and the charger automatically shuts off when the cells are fully charged.

This one is fitted with a large front carrying basket and two detachable saddle bags in the rear. Its main function will be fetching groceries.

Gears

The bike has derailleur gears, like a standard bike. These are purely for human power when the battery is dead. The electric motor bypasses them. You don’t need them much since motor gives you such a boost at slow speeds. You could easily leave the bike in high gear all the time. Electric motors have great torque and acceleration at low speeds.

Theft

The salespeople spent considerable effort persuading us the bike was less likely to be stolen than a regular bike. Bike theft is only a misdeamenor, even if the thief steals hundreds of bikes and the bikes are worth over each, there is zero risk of jail time. In contrast, electric bike theft is considered a form of car theft with jail time. There are no quick release components to tempt thieves. Joyriders can’t do anything without the key and such a bike is a bit of a klunker, less fun than a standard bike for speed. Integration of specialised components make them worthless on the resale market. The bike is distinctive and hence harder to resell discreetly. There are not that many electric bikes sold legitimately. They tend to klunky styling, perhaps designed to appear to older people, which again discourages theft. Other models look more like tiny motorcycles or scooters.

Guilty Pleasure

It’s fun to pass a long line of cars by zipping along the bike lane. It is fun to seriously out-accelerate the cars at an intersection. That you can do that might come as a surprise. Newton discovered that acceleration = force / mass . This means you can double the acceleration by doubling the torque of your engine or by cutting your vehicle’s gross weight in half. An electric bike weighs a tiny fraction of a car, hence runs circles around it in acceleration.

Batteries

Most modern bikes use lithium batteries. They cost over ten times as much as lead-acid batteries but the are much lighter, they last longer, charge five times faster, and don’t fade. Ebike batteries are usually rated 10 or 15 amp-hours. Lead acid batteries only deliver about 2/3 of their rated capacity. They are not particulary well suited to deep discharge eBike applications. By comparison, an AA size dry cell has a capacity of about 2 amp-hours. Automotive car batteries are about 50 amp-hours. A higher voltage setup needs proportionately fewer amp-hours to deliver the same range.

Summary

It is not the sort of thing that turns heads like an electric sports car, though some kids did mention how cool the bike was as I rode past on its inaugural run. Any time a stop at a light, the odds are very good someone else standing there will start asking me questions about the bike. It is great conversation starter. Half the exercise of cycling comes from the muscles used for balance. You might find yourself getting even more exercise than with a regular bike, if you got in the habit of using it for commuting and errands. This is nothing like a motorcycle. You won’t be doing wheelies with it.

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