Should one walk or pedal up hills?

Bicyclists have the willing to choose whether they are walking or pedaling up hills. A declaration states that it should be more efficient to ride up to an approximately limiting gradient than to walk. Because for a common steep hill with a gradient of 15 percent, experiment showed that the efficiency for riding is 17,5 percent, while for walking is 12,3 percent.

As far as I am concerned, this desired movement should have the slope of the steep hill and the physical conditions of the bicyclists as the considerable preconditions. For instance, for the oxygen consumption under the same uphill slop and cycling speed, the amateurs of course behave less sustained as the professional bicyclists, so that after certain travelling path, they would prefer to walk to save energy. In the same respect, if the steep hill is with a high slope, let’s say 58 percent (30 degree), I bet that even though for those profession cyclists, they would opt for walking.

Reference: I. McDonald, Statistical studies of recorded energy expenditures of man. II. Expenditures on walking related to age, weight, sex, height, speed and gradient, Nutrition Abstracts and Reviews 31 (July 1961): 739-762.

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An electric vehicle you can carry in hand

In this time, I will talk about another sustainable “electric vehicle” which you can carry in hand, boosted board. Boosted boards are a souped-up version of a skateboard that runs on a tiny motor, powerful enough to take you up the famous hills of San Francisco at 10 miles per hour (around 16.1km/h). The boosted board can reach the top speed at 20 miles per hour (around 32.2km/h). It weighs 4 pounds (1.8kg). And its battery has a range of 6 miles. It has regenerative braking to allow you to stop easily and recharge the battery at the same time.

As said in the video, when you get off the public transportation system, such as train and bus, how do you get along the last mile to your destination? Definitely, boosted board can be a good choice.

Reference: http://blog.ted.com/2013/02/27/an-electric-vehicle-you-can-carry-in-hand-sanjay-dastoor-at-ted2013/

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Monster: ‘Fat’ Electric Bicycle

An electric hub motor, plus a bulky battery package? What comes to your mind? Yes, that could be a familiar stereotype of each electric bicycle. But have you ever heard of this monster creature in the electric bicycle world—‘fat’ electric bicycle. What on earth could that be?

With 4+ inches wide wires, there is no wonder it turns out to be a freak in the world of electric bicycle. It is designed especially to deal with all kinds of topography, for instance, terrain like sand, snow, jungle and so on.

Based on the conventional design of electric bicycle, this ‘monster’ is equipped with extra electric assist as well, which increases the joy of riding it. If you are considering to purchase such bicycle, the type with titanium material is highly recommended, due to its lower cost and lighter weight.

Reference: http://www.havefunbiking.com/hfbnews/newspublish/newspublish.php?news=Ways-to-Ride-in-the-Snow?-Check-Out-This-%22Fat%22-e-Bike-Guide-(w_Videos)-&news_id=258&start=10&category_id=0&parent_id=0&arcyear=2014&arcmonth=1

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Tips for Buying an E-bike

Based on what we talked before, you may have a certain knowledge about e-bike. E-bike is the most economical, practical, and fun way to get around, no matter for hauling goods, commuting long distance, or just a leisurely. However, choosing what kind of e-bike you need is not as simple as you thought. In the following paragraph, I will talk about the important considerations of buying an e-bike.

  1.  Stay away from electric bike brands with proprietary systems if the brand is not being sold widely in Europe.
  2.  Test riding an electric bike allows you to have the answer of the basic questions, “Do I love this bike”, “Does it climb hills in the way I need it to?”, “Does the bike fit me in the way I would like it to”, “Does it have the quality and functionality I would like?”.
  3. Buy local. If you have any problem with your e-bike, you can get help very soon.
  4. You get what you pay for. For throttle operated bikes or bikes with a cadence sensor, expected to pay at least $1500. For ebikes with a torque sensor, expected to pay over $2500.
  5. Take a longview. You should expect that your bike should last from five to ten years at a minimum with regular service, and that your battery should last from 600 to 800 full charge cycles.  And when the battery needs to be replaced, your retailer should be ready to have it rebuilt or recycled, but not thrown in the trash.
  6. Judging the bicycle component quality by looking over the listing of part. For motor and battery, you can research their brands.
  7. Choose your retailer wisely. Is the staff friendly, knowledgeable and helpful? Do they have many ebikes or just a few stuck in the back of the shop? Are their brand names that you can research?
  8. Warranty is very important. A two year warranty on parts, motor and battery is reasonable to expect from most electric bike manufacturers with product selling for over $2000.
  9. Electric bikes are designed for different people and different purposes. It’s up to you to decide what is most important to you, what is not important at all, and then communicate that to the retailer. If comfort is key, then a step-through frame might be best. If hill-climbing is crucial, then a hub motor over 250 watts or a mid-mounted motor is what will work. If riding long distances is your cup of tea, then a large battery of over 400 watt hours is paramount.

Reference: http://www.electricbike.com/buying-tips/

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Sustainability:Copenhagen wheel

Smart, elegant, and intelligent, being well-known for its smooth red hub, the Copenhagen wheel becomes the most beneficial treasure for urban transportation. Designed by MIT’s SENSEable City Lab, it possesses a specific feature of transforming almost every ordinary bicycle into electric bicycle.

Powered by a 48V rechargeable battery, with an internal gearing system and motor, the wheel is in fact a smart sensing self-contained unit, which can work at a range of 30 miles. With the existence of the gearing system, the wheel is able to capture the energy dissipated while user is cycling and braking, which can be saved for whenever a little boost is needed.

Controlled through a smart phone, the Copenhagen wheel also maps pollution levels, traffic congestion, and road conditions feedback in real time. Users are able to control how much motor power for assistance, to lock and unlock the bicycle, as well as to change the gear ratio. When users are cycling, the sensing unit of the wheel also analyze the environment, for instance, road condition, noise, relative humidity and so on. And as users wish, they can share the data with friends or tune the information on their city.

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Case Study 1: E-bike, Antidote? Poison?

There are around 120 million e-bikes on China’s roads-up from 50,000 a decade ago, making it the fast growing form of transportation in China. At first, cities embraced them as a quieter and cleaner alternative to gasoline-powered scooters.

However, officials were caught off guard when this environmentally appealing solution turned out to be deadly on the streets. In 2007, there were 2,469 deaths from e-bike accidents nationwide, up from just 34 in 2001, according to government statistics.  That’s roughly 3% of China’s annual 90,000 traffic accident deaths. The reason for the increasing traffic accidents caused by e-bike could be that drives of electric bicycle don’t need to pass stringent driving tests to get licensed.

Due to the development of battery and engine technology, the China’s e-bike industry started under the planned economy of the Maoist 1960s. After China liberated its economy in the 1980s, a handful of entrepreneurs tried to revive e-bikes just as city planners were worried about the explosive growth of exhaust-spewing mopeds and scooters. By the 1990s, cities were starting to ban motor scooters, and creating an opening for e-bikes. E-bikes were supported by the government, including 10 key scientific development priority projects in the Ninth Five-Year Plan. By 1998, regulators realized they also had to limit the speed and size of e-bikes. The original standards limit the maximum speed of an e-bike to 20 kilometers per hour (a little more than 12 mph). But e-bikes’ power soon outpaced that.  Some capable of 25 mph.

In order to avoid the crowed public transport, more and more people (for example, commuters) chose to own an e-bike, which brought a large increase in e-bike sales from 1.5 million in 2002 to 4 million in 2003. However, e-bike fatalities rose too. In 2003, 87 people were killed in e-bike accidents. A year later, the number rose to 589. The deaths led to a backlash. More and more cities decided to ban e-bikes; or set up checkpoints and penalize the e-bikes which violated weight and speed restrictions or didn’t have proper registration.  Another problem is e-bikes may not be so clean after all, because 95% of China’s e-bikes use lead batteries, they emit more lead into the atmosphere than other forms of transportation. They also rely on electricity that’s mostly made by coal-burning power plant.

Well, we should also respect the public opinion. “The e-bike is a necessity for my work. The fastest and cheapest traffic vehicle I can afford. It’s the same for most riders here. I can finish my work on the bike. There are no buses in many places and I can’t afford to buy a car. What do you expect me to do?” said Mr. Yu. Due to the new battery technology (Lithium battery), the pollution of the battery can be solved. And the government can also improve the regulation for e-bike which will enhance the safety for it.

Should we ban e-bikes or not? Should we look at it from the perspective of government or the public?

Reference: http://online.wsj.com/news/articles/SB20001424052748703657604575005140241751852

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History Of Electric Bicycle

The electric bicycle dates back to around 120 years ago. Even before the first appearance of the electric bicycle, in 1867 and 1886, two inventors invited motorized bicycle that used steam engine and internal combustion engine.

Figure1_Ogden Bolton Jr

Figure1_Ogden Bolton Jr

At the end of 1895, one of the first patents for electric bicycle was issued by Ogden Bolton Jr (Figure1). Mr Bolton wrote that his invention includes: “6-pole brush and commutator direct current (DC) hub motor mounted in the rear wheel. It is surprising that the hub motors invented 120 years ago are still vastly used in the electric bicycle industry and it is one of the best ways to propel the electric bicycle.

Two years later, Hosea W. Libbey invented an electric bicycle with two motor, two batteries and two wheels (Figure2). Does this sound crazy? The purpose of this crazy behavior is to realize the electric bicycle controller. One a plain road, only one battery would work and when climbing the second battery will also come into action. In the original design of Mr. Horesa, the motors used crank rods to rotate the wheels. After a short while, he changed these big clumsy rods to more efficient chain drive (Figure3).

Figure2_Hosea W. Libbey

Figure2_Hosea W. Libbey

Figure3_chain drive

Figure3_chain drive

In 1898, Mathew J. Steffens issued a patent of an electric bicycle that was operated by a belt that was placed on the periphery of the back wheel and also around the motor (Figure4). The slots on the wheel can prevent the belt from slipping away. Anyway, this kind of propulsion system is very creative.

Figure4_Mathew J. Steffens

Figure4_Mathew J. Steffens

Following the belt drive system, an idea for a friction drive came in reality. In 1899, John Schnepf introduced a bicycle which used a pulley that rest on the top surface of the rear wheel (Figure5). The pulley rotated with the help of the motor and in turn propelled the rear wheel. In 1969, A. Wood Jr was inspired by the invention of Mr Schnepf and turned it to a more complex friction system consisting of 4 different motors (Figure6). Each one of them was pushed to the front wheel.

Figure5_John Schnepf

Figure5_John Schnepf

Figure6_A. Wood Jr

Figure6_A. Wood Jr

In 1946, Jesse D. Tucker assigned a patent for a motor with internal gearing and with the ability to freewheel. Due to the creative design of Mr Tucker, the cyclist can choose whether to use pedals in combination or without combination of the electric motor.

Nowadays, with the help of other invents, such as torque sensors, power controls, new batteries and better hub motors, and advanced technology, electric bicycle has become a big industry, with the fact that there are roughly 120 million e-bikes on the roads of China, and in USA and Europe, the number of electric bicycles sold are in millions now.

Reference:

Text:  http://www.electric-bicycle-guide.com/electric-bicycle-history.html

Figures:

Figure1 http://www.google.com/patents?vid=552271

Figure2 http://www.google.com/patents?vid=596272

Figure3 http://www.gngebike.com/36v350w-48v400w-gen2

Figure4 http://www.google.com/patents?vid=613732

Figure5 http://www.google.com/patents/US627066

Figure6 http://www.google.com/patents/about?id=BFhrAAAAEBAJ

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