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How to Choose an Electric Bike


Here's how to choose the right electric bicycle to
suit your personal needs...

Cost of Operating Electric-Powered Bicycles...

Electric bikes are revolutionizing the bicycle industry. Not
only is riding an e-bike simple and easy, but a rider can significantly extend their range with minimal cost or effort. Within the last several years alone, electric bike sales have skyrocketed and dozens of manufacturers have jumped on the bandwagon with new electric bike models. With so many different options to choose from, how do you choose the
right e-bike to suit your needs? In this article we'll discuss the different options so you can make an informed decision.

Before you start shopping around for a new e-bike, the first thing you should ask yourself is, "how do I plan on using an electric bicycle?" Take some time to ponder this question, because it's the most important factor in determining the best product to suit your personal preferences. How far do you plan on traveling? What type of terrain will you be traveling on? How much assistance do you need? Do you plan on pedaling - or do you want the bike to do all the work? Is this bike for daily commuting or casual riding? How fast do you need to go?

General E-Bike Options

After you've determined how you'll be using your e-bike, you need to understand the different options available and the pros and cons of each setup. Here are some of the choices you'll have to make when you choose an electric bike:

There are two main categories when choosing an e-bike:
a pre-built electric bike or a custom e-bike conversion. Pre-fabbed electric bikes come in a wide variety of setups and styles and are designed specifically as electric bicycles. With unique characteristics and design qualities, most meet Federal and International Laws which limit power and speed. Choose from cruisers, commuters, mountain bikes and more. Select different motor and battery configurations for different riding styles or preferences. Pre-built e-bikes are clean and 'stealthy' with all of the wiring and electrical components built directly into the bike. For most people, pre-built e-bikes work great and there's no need for a custom conversion.

Conversion kits, on the other hand, are sold and installed separately on traditional bicycles. Harder to setup and conceal, installing one will require some basic mechanical ability and a little bit of 'elbow grease'. But you can choose almost any standard bicycle, and unlike pre-built e-bikes, you have the freedom to change or upgrade components as you go. A conversion kit will also allow you to achieve higher power and speed ratings that are not possible on most pre-built electric bike models. Kits are great for tall or heavy riders because they can choose a larger bike and they have higher power and weight carrying capacity. People living in mountainous terrain may require the additional torque to handle extremely large hills or inclines. And for people who prefer a specific bike model or love to go fast, a conversion kit provides enormous flexibility.

Electric bicycles have two main methods of operation: pedal-assist and/or throttle-control. As the name implies, pedal-assist 'assists' your pedaling and requires some input. With this method, a torque sensor picks up movement or stress to determine the power requirements of the rider. Everything is automated so there's nothing to think about, just jump on and start riding. Some bikes have multiple settings, while others have just one setting with the addition of a throttle control. Depending on the setting, pedal-assistance can help a little - or a lot. At lower settings, pedal-assist is barely noticeable but helps extend your range. At higher settings, the power is quite obvious and feels like a strong wind on your back with the motor doing most of the work while you pedal along.

A throttle-control, on the other hand, doesn't require pedaling at all. Just like a motorcycle, twist and hold the throttle back to control power and speed. You can assist by pedaling along, but it's not required.

Some e-bikes operate in pedal-assist only, others have a throttle, and some have both. Generally, pedal-assist only bikes will provide multiple power settings to choose from to help customize your ride, while bikes with both throttle and pedal-assist will have limited pedal-assist options. With these bikes, the throttle provides full control (when needed) while pedal assist is just a secondary option, great on straight-aways or open road.

These days, most electric bike models include brushless 'hub motors' built directly into the front or rear wheel. But a few lower-cost setups (such as the EZIP line) use externally mounted, chain-driven motors. Although these setups are lower-cost and provide a good amount of torque, they're not nearly as quiet, efficient or 'stealthy' as the hub motors being used on most e-bike models. Within the hub motor category, you'll have a few additional choices available:

Geared Hub Motors - Most pre-built e-bikes use brushless 'geared' hub motors. These motors have internal planetary gears that help transfer power from the motor to the wheel. Because of the internal gearing, these motors provide excellent torque but are limited in top speed. On the plus side, the improved torque means better take-off power and hill climbing ability. Plus, less wattage is required to get the motor turning and they're typically small and lightweight. On pre-built e-bikes, these motors range from 200w-500w and go up to 20mph. But some aftermarket kits can be as powerful as 1000w, with increased top speeds and huge amounts of torque (ideal for extremely hilly terrain). Besides lower top speeds, these motors tend to be expensive and it's possible the gears will eventually wear out and need to be replaced.

PLEASE NOTE: Our shop has been open 4+ years and we have not had to replace gears in a geared hub motor yet. They last quite a long time!

Gearless (Direct-Drive) Hub Motors - Some conversion kits (and bikes) use gearless, direct-drive motors. They work by sending alternating current signals to magnetic windings inside the motor, causing it to turn. Even though corrosion will eventually have an impact, this type of motor should last for years since there's no gearing and no contact between moving parts. They're also capable of higher top speeds. But since there's no gears, they have less torque and it requires more power to get the motor up to speed. This means direct-drive motors are larger and heavier. Most direct-drive hub motors (ie: E-Bike Kit) are 350w-500w and reach speeds of 18-25 mph. But more powerful motors (ie: Crystalyte) and can reach speeds of 35+ mph.

There's two different configurations for hub motors: front or rear-mounted

Front-Mounted Hub Motor: Front hub motors can be found on pre-built bikes or on conversions. Mounted to the front wheel, this is the easiest configuration to setup if you're converting a standard bicycle since there's no derailer or chain to worry about. And since most e-bike conversions include batteries mounted to the rear rack, using a front hub motor helps equalize the weight of the bike and makes it easier to handle. But there's a small risk the motor could cause the front forks to fail. That's why it's vital you only use a front hub motor on a steel fork. For pre-built bikes, this shouldn't be an issue since the motors are usually lower-powered on steel forks.

Rear-Mounted Hub Motor: Rear hub motors, installed on the rear wheel, are more common on pre-built bikes because they're easily installed at the factory. For a conversion, it's a little harder to install than a front hub motor because of the chain, gearing and derailer. Plus, you may be limited to a 6 or 7-speed freewheel. But a rear wheel will provide more torque and is less noticeable than a front hub.

The biggest factor in determining the overall cost of an electric bike is the battery. There are several different battery types and they come in various shapes and sizes. Typically, pre-built e-bikes are limited to the SLA or Li-Ion batteries included with the model. But you'll have a few more options with conversion kits. Here are three main types of batteries and the different 'sub-categories' you need to be aware of when choosing an electric bike:

Sealed Lead Acid (SLA) - The most affordable battery option, but also the heaviest with the least amount of life. SLA batteries are good for beginners or anyone concerned about cost. With a kit, you can easily start off with SLA, then upgrade later. At about 7-8 lbs per 12V battery (x2 for 24V, x3 for 36V, x4 for 48V), they can get quite heavy. SLA batteries typically last 300-500 charges (1-2 years). These batteries are very sensitive and can be damaged if you drop below 75% charge on a regular basis. They also get weaker towards the end of life or near the end of charge cycles.

Nickel Metal Hydride (NiMh) - A nice moderately priced battery option, NiMh batteries are smaller, lighter weight and longer lasting than SLA. Since most pre-built bikes use SLA or Li-Ion, this is only an option for people doing an e-bike conversion. NiMh weights about 1/2 the weight of SLA and will last 2-3 times longer at 400-600 charges (2-3 years). They also have a more equalized discharge rate, meaning they won't weaken as much towards the end of life or at the end of a charge cycle.

Lithium Ion (Li-Ion) - The longest-lasting and lightest-weight battery option, but also the most expensive. Li-Ion is a generic name with several subcategories. Be sure you understand the different types because many websites, dealers and manufacturers will overstate their ratings assuming you don't know the difference:

  • Lithium-Cobalt (LiCoO2) - Common in laptops and cell phones, but not common in e-bikes. Very lightweight, but unstable and unsafe. Fire hazard!
  • Li-Manganese (LiMnO2) - The most common Li-Ion chemistry used in e-bikes, LiMnO2 is almost always generically referred to as "Li-Ion" or "Lithium Ion". If no other specification is provided, this is most likely the type. LiMnO2 is the most affordable type of Li-Ion, and although significantly lighter than other battery types, it's the heaviest Li-Ion chemistry. If someone states 1000+ charges, they're overstating the ratings! This type of Li-Ion typically gets 500-800 charges.
  • Lithium-Polymer (LiPo) - Slightly more expensive than LiMnO2, LiPo batteries have similar ratings. The difference lies in the construction, since LiPo batteries do not have hard metal casings but are wrapped in a flexible (polymer) material.
  • Lithium-Phosphate (LiFePo4) - Top-of-the-line Li-Ion chemistry! This is the longest-lasting and lightest-weight battery chemistry available! LiFePo4 is very expensive but will last 1500-2000 charges and has the most equalized discharge rate out of any battery type. This means they provide full power throughout most of their life and they won't weaken towards the end of a charge cycle.

E-bikes are typically offered in 24V, 36V and 48V configurations. Higher voltage generally means higher top speed - but this isn't always true (check ratings). Since the efficiency of a motor and drive system can have an effect on power and speed, a 24V setup could have the same top speed as a 36V setup. But generally, higher voltage bikes are faster. Expect 15-18 mph on a 24v setup, 16-20 mph on a 36V setup and 24-28 mph on a 48V setup. Although it far exceeds Federal laws, some conversion kits can even be run at 72V for speeds of 35+ mph! But this puts significant stress on bicycle components. Consider that even the fastest athletes only travel 17-18 mph on a bicycle. 20 mph feels very fast to most riders. Anything over this speed can be unsafe and exceeds Federal law.

Also consider that higher voltage means more batteries. More batteries means higher cost and additional weight.

Batteries are rated by voltage (V) and amp hours (AH). Although voltage seems to get the most attention, just as important is the amp hour rating of the battery. AH is the measure of a battery's capacity. It provides a good indication of the range you can expect from an electric bike. Although lots of factors come into play (ie: rider weight, terrain, input, efficiency, etc.), a good rule of thumb is range is equal to AH. So under normal conditions, an average rider can expect 10 miles out of a 10AH battery (with no pedaling). With rider input, this number can be dramatically increased, so most 10AH batteries are rated "up to 20 miles" by the manufacturer which assumes pedaling.

On pedal-assist bikes (which require pedaling), the range ratings are much higher. That's because the rider is constantly assisting the motor and reducing the current draw.

Electric bikes vary widely in price, anywhere from $499 to $2000+, so you'll have to determine how important certain items are to the overall cost. Batteries definitely have the biggest impact. Is it worth investing in top-of-the-line LiFePo4 batteries, or will a lower cost, heavier SLA battery be satisfactory? If you want more power, it's going to cost more. Is it worth the extra money for higher torque and faster speeds? What about range? It's going to cost more for higher capacity batteries or a more complex PAS system. Is it worth it the extra money? What do you really need?

At first glance, choosing an electric bike may seem intimidating. But don't be overwhelmed by the different types of bikes, motors and battery options. The first thing you need to do is ask yourself, "how will I be using this bike?" Once you determine how you'll be riding, you can eliminate many of the options and refine your search. Remember, bigger isn't always better! In the case of e-bikes, bigger means heavier. Do you need 30+ miles of range, or is 10-15 miles more realistic? Is your terrain mostly flat, or do you have some hills and inclines? Do you plan on pedaling, or do you want the bike to do most of the work? How important is the weight of the bike? Will you be loading or transporting it? Figure out exactly what you want to accomplish and the goals you want to achieve. This will help you choose the right e-bike.

  1. What's your budget? A bigger budget equals more range, longer life and lighter weight. A smaller budget creates limitations.
  2. What type of terrain will you be traveling on? Flat terrain will require less power, torque and cost. Hilly terrain may require your assistance or more power.
  3. How much pedaling do you plan on doing? If you plan on pedaling a lot, a higher power system may not be necessary and pedal-assist is a good option. Otherwise, a throttle and increased power may be needed.
  4. What type of range do you need to accomplish? If you're within 10-20 miles, most e-bikes will do. But more range will require more assistance or larger batteries.
  5. Is weight a factor (bike or rider)? Most e-bikes can handle up to 250lbs, but expect reduced range with more weight. Consider a kit for more carrying capability.
  6. How fast do you want to go? 15-20 mph feels fast on a bicycle! And the law says anything over 20 mph isn't a bike. Choose a kit if you want more speed.


* Have questions or need a suggestion? Please contact us! Or, visit our e-bike forum
for tips, advice and user experiences.
 

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