Learn About Electric Bikes

The Different Types of Electric Bikes

BMX

"Bicycle Motor Cross" - Includes race bikes, dirt, street, flatland, and free-style. They are smaller and stockier than other bikes with simple frame structure and large tires. Various gears are rare; they usually have one gear, and minimal brake fixings. They are created to handle the difficulties of BMX courses. They are hard, light, powerful, and easy to move on the ground and in the air. 

Cargo

Electric cargo bicycles can carry boxes or even children, and have some sort of rack on the back or front.

City

Since it is hard to determine if a bike is a Comfort, Commuter, or Cruiser, this site has lumped these all into "City" bike; they are all made to operate on the city streets.

Comfort

The key features are upright riding style and step-through frame for easy mounting, wider saddles and wide swept-back handlebars shown here. These all promote comfortable riding; similar to Cruiser style.

Commuter

These include Comfort style bikes, and Cruiser style, which are suitable for commuting. Distinctions become blurry. Fat tires are suggested for long term use since they can better protect from potholes and bumps.

Cruiser

Generally have fat tires for riding on soft unpredictable land like sand on a beach, snow, and mud. But they are also perfect for city riding and provide upright seating, big soft seats, and wide swept-back handlebars.

Fat Tire

These generally have tires 4 inches wide which allow you to run over potholes, mud, rain, sand, or other city obstacles which makes them generally safer. Good for beach cruising. We include 3 inch tires in this category, in our selector.

Folding

These can be folded to fit in the back of any car or SUV. Or take it along on a bus.

Mountain

Built to handle rough off-road terrain. There are three types:

Hard-tail - have front shocks to handle rough bumps, but not rear shocks. 

Dual Suspension - all terrain allows you to sit in comfort.

High performance - when cost is no matter. Built to climb up any hill, have power motors above 500 watts.

Batteries can be mounted on the seat post (lower priced bikes); on the rear rack (mid-priced bikes); or integrated into the frame (higher priced bikes) which is preferred because it best protects the battery from the elements.

EBike Components

Source: Al2, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

How do Ebikes work?

Most electric bikes have pedal assist, which allows the rider to decide how much power should be provided by the motor. The harder you pedal, the more the motor assists. When you stop pedaling, the motor stops assisting. Some bikes measure the speed you are pedaling (cadence sensing) and apply power for the smoothest ride. Others measure the torque or pressure against the pedals, and provides a similar experience as a regular bike where you need to put in more leg power to go faster.

Some bikes have a manual throttle which allows the rider to access power on demand, and cruise without pedaling. Most bikes have both pedal assist and throttle control ability.

Motors

There are two main types of motor drive systems: hub-motors and mid-drive motors. Hub motors are located in the center of either the front or rear wheel hub, while the mid-drive motor is located in the crank where the pedals are.

Direct-drive hub motors are always engaged, and can be used for regenerative braking; that means that the bike is slowed down by converting the motion into electricity used to recharge the battery. These motors have no moving parts and are very quiet.

Geared hub motors free-wheel when the motor is not being used, that offers no resistance and can't be used for regenerative braking. They have moving parts which are louder than direct drive, but also faster.

Mid-drive motors connect to the rear hub by a drive belt, which makes it more effective on steep hills because it can take advantage of the bike's existing gears.

Front-hub drive motors propel the front wheel, while the rider propels the back wheel. But a rear-drive motor can offer throttle, cadence, and torque sensor pedal assist, while front hubs can't offer torque sensor pedal assist. Cadence means: As you pedal, the controller is counting the rotations on the crank and is providing power accordingly. And a torque sensor measures the pressure of your foot on the pedal. With cadence, you don't have to keep any pressure on the pedals at all, you can switch down to a lower gear and just rotate the pedals. This is useful if you have a physical need.

Wheel-hub motors are generally less expensive than mid-drive motors,

The wattage rating of the motor determines how powerful it is. Most bike motors fall within 250 – 1,000 watts. This is the amount of power that a motor can continuously produce. A 350 watt motor is generally less expensive and lighter than the higher power motors which are not stingy on performance.

Front, Middle, and Rear Wheel Motors Compared

There are advantages and disadvantages to each.

The rear wheel hub motor provides very good traction since the rear wheel carries the most weight, and is well suited for inclines and wet conditions. But the removal of the rear wheel is difficult. The motor is equipped with special components that are generally more expensive. The rear wheel hub motor has technically more complex control and wiring compared to the other motor types.

The front hub motor is the simplest and cheapest option; not many bikes have this. Most of the weight of these e-bikes is on the front wheel, which affects the driving behavior somewhat. With a front hub motor, you can sometimes hear noise. 

The mid-motor offers a natural driving behavior because the engine power is optimally matched to the pedaling force and there is an optimally low center of gravity. Wheel removal and an integrated force measurement are possible. The costs are usually somewhat higher because the drive is fully integrated in the frame. The center motor can take advantage of the gears on the rear wheel.

Torque Sensor vs. Cadence Sensor

Torque and cadence sensors tell your motor how much pedal assistance to provide. Which is better? The torque sensor measures how hard you are pedaling; the less expensive cadence sensor measures how quickly you are turning the pedals.

Electric Bike Co. explains Torque Sensor: While the term sounds technical and a bit intimidating, a torque sensor is simply a sensor that detects how hard you are peddling and then adds a proportional amount of assistance. As you pedal, the torque sensor kicks in and matches the effort with motor power that makes riding easier and more enjoyable.

A cadence sensor measures the rotation of the crank (the thing you pedal) in pedal revolutions per minute. The faster the pedaling speed, the more power is provided by the motor. One disadvantage of a cadence sensor is there is delay from the time you start to pedal, to the time the controller senses the motion and kicks on the motor.

If you are riding along a road and come upon a hill, if you are pedaling at the same rate you will get the same assist from a cadence sensor so you may have to change the assist level. A torque sensor will sense the increased torque on the pedal and increase the power from the motor; it is a more natural experience.

The Derailleur

The derailleur is the gear shifter; the most common brand is Shimano. This video shows the derailleur in operation:

Suspension Front Fork

The front fork provides a smooth ride; if it has a lock setting, you can lock it for flat roads, and unlock it for rocky hills.

It allows the front wheel to move up and down to absorb the bumps. 

Batteries and Battery Capacity

A battery with a low center of gravity has a more stable riding experience. Batteries placed on the rear rack make the bike more unstable and rear-heavy.

Batteries are compared by watt-hours which is a measure of the energy storage of the battery and is the biggest factor in determining range; it is equivalent to the amount of fuel in a gas tank. To get watt-hours, you multiply the voltage by the Amp hours (Ah) labeled on the battery. A 36V 10 AH battery can produce 36x10 = 360 watt-hours, or 360 watts for 1 hour, or 180 watts for 2 hours, etc.

The range of the battery equates to how many miles you can get out of a single charge, which depends on how much battery assistance you plan on using. The more you pedal, the longer will be the range on a single charge. Typically you can get between 20 to 60 miles on a charge, though some bikes go up to 200 miles.

Why do Manufacturers use higher battery voltages?

Voltage is equivalent to water pressure in a pipe. For a given size pipe, if you want more current to flow, you need higher water pressure. For a given size wire, for more electrical current to flow you need a higher voltage. 

Wire resistance is equivalent to water pipe size. A bigger wire, or bigger diameter pipe, will allow more current to flow for a given pressure/voltage. 

Higher battery voltages are more efficient and have less losses, which allows using smaller diameter (less expensive) wire connections to the motor and battery, and also the motor itself can be built will smaller wire.

Here is the long answer for techno-nerds:

A 12 volt battery capable of producing a current of 4 amperes can produce 12 x 4 = 48 watts of continuous power.

A 48 volt battery capable of producing a current of 1 ampere, can also produce 48 x 1 = 48 watts of continuous power.

Both batteries have the same physical size and can produce the same continuous power. But losses in the interconnect wire and motor windings (and even in the battery itself) are proportional to the square of the current.

For a given wire resistance R:

For the 12 volt battery, losses are (4 amps)² R = 16R.

For the 48 volt battery, losses are (1 amp)² R = 1R.

Thus, for a given wire resistance, the 48 volt battery wastes 1/16 the power of the 12 volt battery, which is used to heat the wire and performs no useful work.

However, to reduce costs, manufacturers will use a smaller diameter wire; the wire size required for 48 volts is one-forth the size of 12 volts. This takes up less space and reduces manufacturing costs.

And the motor itself, operating at a higher voltage, will operate at a lower current. The losses in the motor are based on the square of the current; these losses are converted into heat and produce no work. When pushed to perform, bikes with lower voltage (and therefore higher current) will produce more heat, and there is a limit to how far you can push them before they overheat. A higher voltage (and therefore lower current) allows a motor to produce more thrust before it overheats.

The less expensive bikes come with 24 volt systems, while the most expensive come with a 48 (or 52) volt system. 

How high can battery voltages go? Higher voltages start to become dangerous to humans at about 60 volts.

Tires and Fat Tires

Most normal tires are around 2-2.3 inches thick. A fat-tire bike is an off-road bike with much thicker tires around 4 inches that are better suited for riding on soft terrain such as sand, snow, and ice.  If you only need a bike to ride to work, a regular electric bike will do. But if you have to deal with mud, snow, or ice, fat tires are a great option.

Classification of Electric Bikes

Due to legal purposes to help lawmakers determine how to regulate ebikes, they fall into three categories:

Pedal Assist (aka “pedelecs”)

The motors only work when the bike is being pedaled. The motors are activated by a pedal-action sensor. These types of bikes are limited to 20 mph and motors that do not exceed 750 watts. Most bikes allow the rider to select the amount of motor assist to fit their needs and geography.

These are good bikes for all-around use.

Power on Demand

This has the added feature from pedal assist, of allowing the rider to activate the motor without any pedaling, by use of some throttle or button. These models are also limited to 20 mph and 750 watt motors.

These are also good for all-around use, but have the ability to handle a physically strenuous ride.

Speed Pedelecs (aka “S-pedelecs”)

Speed pedelecs are similar to normal pedelecs, with the added ability that the rider can combine his pedaling effort with that of the motor, and achieve speeds in excess of 28 mph. These lack a throttle, but can be equipped with a motor up to 750 watts for pedal assist purposes only. Check your local laws, as these might require a driver license and registration, and might not be allowed on bike paths and lanes.

Class 1, Class 2, and Class 3

Class 1 e-bikes (in the United States) can reach speeds of up to 20 mph (32 km/h), but require the rider to pedal to engage the motor. Class 2 e-bikes can reach similar speeds but have an additional hand throttle; they can be ridden like motorbikes and do not require pedaling to activate the motor (though most also have pedal assist systems to function like Class 1 e-bikes). Class 3 e-bikes are similar to Class 2 e-bikes, except that they can reach higher speeds of up to 28 mph (45 km/h).

California Code, Vehicle Code - VEH § 312.5  (As of 1/1/2019)

Laws governing electric bikes can be confusing, but in general most regulations allow for a maximum speed of 20 MPH when used in motor-only mode; of course they can go faster than 20 depending on how hard the rider is pedaling. Electric bikes can be ridden just like regular bikes on bike lanes, bike paths, and can be locked up on bike racks like regular bicycles. But it is important to check out the local laws.

National Parks

E-bikes are permitted in all national parks on any trails open to pedal vehicles. They are classified as "non-motorized bicycles". All three classes of e-bikes (described above) are allowed, but Class 2 and Class 3 e-bikes must not use the throttle control; these must be pedaled like Class 1 e-bikes while on national park trails. According to an email from Electric Bike company, Feb. 2022, the NPS (National Park Service) says we can enjoy the beautiful sights of America's great outdoors while staying safe on our E-bikes. This is why we are now allowed to ride:

• Efficiency. E-bikes are an efficient mode of transportation that encourage more people to get out and explore.
• To assist those who have physical ailments, are older, live with disabilities in getting out and exercising.
• Reduce emissions from people driving into National Park locations.
• Decrease road congestion.

 As exciting as this is, there are still a few rules you need to abide by:

• Bike lights & a helmet are a MUST
• Make sure you take care mounting and dismounting your E-bike.
• Always carry a map.
• Make yourself aware of the areas e-bikes are not permitted before setting off.
• Check if your class of E-bike is allowed in your chosen destination.
• Fully charge your bike and bring charger on your ride

Bike Maintenance

1) Be sure to check the tire pressure every 2 weeks, once a month at the latest. Bike tires lose air pressure quickly.

2) Clean the chain, and lube the chain. Do not use WD-40; that is not a lubricant, that will actually dry your chain out. You can use it to clean the chain, and then follow up with a lubricant. There is a version of WD-40 that says on the bottle Chain Lubricant; otherwise it is a penetrant. Tri-Flow is a lubricant. 

3) If your brakes squeak, take your caliper off, take the pads out, spray them with Disk Brake Silencer (labeled on the bottle); but 9 times out of 10 it just needs adjustment. Do a visual inspection down the disk, and a lot of times there is an adjustment on each brake pad, from the back side or front side. Align that so the wheel spins freely and is not dragging. 

The lubricant provides a cushion from metal on metal.

4) The derailleur can be adjusted. See the video below, at 8:00.

5) 95% of bikes on the market are water resistant, but not waterproof. The motor, display, throttle have no problem; you can put direct water on them and wash the bike down, wipe with a sponge. The controller is the most vulnerable part, and for it to fail you would have to submerge it in water. Where the cable comes in to the brake handle or other part, try to keep it lubricated.

5) If you get a flat tire, don't try to remove the whole wheel and change out a tube. Carry a patch kit. 9 times out of 10 it's a puncture, not a blowout. You can change and fix the tube without removing the rear wheel. See the video at 15:00. 

6) Don't let your battery run to zero. If not being used, recharge at least every month, two on the outside, otherwise the battery will no longer hold a charge and will need to be replaced.

7) Carry a tool kit: Allen wrench set (sizes 3,4,5, and 6 for most modern bikes; sometimes 8 and 10); tire irons (you need 2); patch kit, a mini-pump (or CO2) so you can adjust tire pressure on the trail, and a cell phone as an emergency backup last resort.