Required knowledge for making a successful ebike kit purchase.

Read “How to buy a motorized bike kit” for additional details and information on ebike kits & “E-bike conversions” for some purchasing suggestions. For specific questions on anything ebike related or just to get some ideas on ebikes visit the two forums listed below. If you can’t find an answer there you probably don’t need to know it. For a short explanation about e bikes click HERE. Finally, if you would just like to know what everybody is talking about, please read on.
V is for voltage

Ebike Kit ComponetsElectric bicycle technology is growing and improving at a rapid rate. A state of the art ebike component this year is probably not going to be the state of the art component for next year. That’s not to say ebikes are subjected to “Moore’s Law” in the way that your PC is, but if your taking up on your ebike research from 2010 you would be wise to update your findings. The following is not a comprehensive list of the terminology used in the ebike industry nor a primer on building an ebike. (For that go here)  It is however complete in such a way that that you’ll be better able to understand the information that is presented by the ebike kit builders.

I broke my list down by the basic components required to turn your bike into an ebike. Many of these terms will be used in describing multiple components even though I have explained them only once. Read this page by for detailed information and reviews on some of these components.

Most advertised ebike kit prices do not include the battery or the shipping charge. These are two of the major reasons for the huge price discrepancies you’ll find in ebike kits. The cost for either one of these can exceed the cost of the ebike kit alone. DO NOT BE LURED BY CHEAP PRICES.

Two final notes – The vast majority of ebike kits are coming from China. The translation from Chinese to English is often so inaccurate as to be barely understandable. In addition to the often accidental mis-information is the deliberate mis-information. (When is a lie not a lie?) These companies are usually very small mom & pop organizations and are not governed by the same rules as their American, Canadian and European counterparts. With that thought in mind, ALWAYS AND WITHOUT EXCEPTION ! Use PayPal or a Credit Card. DO NOT USE YOUR BANK CARD ! It may say VISA but it does not offer the same protection. In the event of a problem, at the very best, you’ll be stuck with bank fees.

Amps, volts, watts, and ohms are the main units used for measuring electricity. Although they are often used in the specifications of many of the following components I have only explained them once. Ohms is a measurement of resistance that is critical for measuring electricity. However, it’s rarely used in marketing material so I did not include it below. Most ebike kits will be advertised using the volts & watts only, i.e 36V 800W wheel motor kit.. Some of the higher quality kits will be advertised using volts, watts & amps i.e. 36V 25A 900W wheel motor kit.  If you remember volts x amperes = watts you can more accuratly determine the output of your motor based on the components you’ll be using.

MOTOR (The engine) Detailed information on hub motors can be found at The Grin Cyclery and at Wikipedia

  • MOTOR (electric) = An electromechanical device that converts electrical energy into mechanical energy. It’s the part of your ebike that, along with you does all the work. See above
  • Hub Motor Geared= Smaller, lighter & with more torque it also free wheels. The down side is they are more expensive, more complicated & slower. They can not be used for regenerative braking. See above
  • Hub Motor Direct Drive= Simple, inexpensive, faster, well tested & reliable. They can weigh twice as much & have less torque. If mountain biking is your thing consider a geared hub or mid-mount chain drive. If you want regenerative braking then a direct drive hub motor is your only option. See above
  • Brushless or brushed= Brushlees motors account for about 90% of todays ebike kits making the brushless or brushed question somewhat academic. See this Wikipedia article for more information on brushless DC motors.
  • Chain Drive= A transmission system in which power is transferred to the wheels by means of a chain. Usually found in ebike applications where the motor mounts in the middle of the frame. Usually in the area of the pedals.
  • Friction-Drive= (FD) A very simple and inexpensive drive system which pushes a electrically powered roller against the the front or rear tire. Read this review by on a new & improved friction drive.
  • Regenerative braking= An energy recovery mechanism which slows the bike down by converting its kinetic energy into either a braking action  or by creating electrical  energy to put back into the batteries. Although this can save wear and tear on the brakes it is probably not cost effective as far as increasing your range. Often refereed to as ReGen. Your money would be better spent on a bigger battery pack. Read this for more information on regen braking.
  • Motor efficiency= Most ebike kits advertise this figure at 80 to 85%. It basically means that the given motor can convert up to 80 or 85% of the available energy into forward motion. This figure is dependent on many things and can be measured in different ways.  The actual overall efficiency of the ebike is dependent on many things among them are the batteries, controller, wiring and wire connectors. So don’t hang your hat on this number.
  • Amps = A measurement of current flow
  • Ah = One ampere-hour is equal to a current of one ampere flowing for one hour. For our use we are concerned with the ampere-hour capacity of our battery. Thats the number of ampere-hours which can be delivered by the battery on a single discharge. The higher the number the longer the run time, the bigger the battery & the more expensive it will be. 8, 10, 12, 15 & 20ah will be the most common
  • V – Volts = A measurement of the electric potential. The higher voltage the more power on tap & the more batteries you’ll need to carry.
  • Watts = A derived unit of power or a measurement of power. I.e. 750 Watts = one horsepower. Hub motors will typically be advertised as 250watts to 1000 watts. To find the actual wattage your motor will be running at use the following formula. volts x amperes = watts. Almost all of the motors being used in todays ebike kits are designed to work across a range of both volts & amps. Hence watts can be subjective number
  • Watt hours = The energy capacity of a battery pack, To calculate multiply the voltage by the amp hours (Ah) of the battery pack. I.e. A 36-volt 10-Ah battery pack has 360 watt hours.
  • RPM = Revolutions per minute. The RPM’s given for a specific hub motor will be the maximum no load operating RPM. Higher RPM translate into more speed and less torque. Lower RPM is less speed and more torque. Conversely a small diameter rim will require a higher RPM motor to achieve the same travel speed as a larger diameter wheel.
  • HP= Horsepower. 1 Hp = between 735.5 to 750 Watts
  • BLDC motor= Brushless DC motor using an electronic motor controller.


  • DC motor controller = An electronic device that reads the throttle setting of your ebike and adjust the current being supplied to the motor. Other functions usually include a low-voltage cutoff , a high temperature shut-off, over-current shut-off. Some controllers will also have a brake cutoff  to shut down the motor when the brake is applied. Some may also have a regenerative braking option. This will often be indicated with Regen being listed somewhere in specifications. Most of today’s controllers will work with hall sensor motors and the newer sensor-less motors. Most DC motor controllers are designed to operate across a range of motor and battery sizes. This gives the kit builder a fair amount of flexibility in selecting a cost effective controller for their kit. However when you combine this flexibility with rather broad operating range of today’s hub motors you can see how easy it would be to “play with the numbers”
  • PMD = Power Management Display = An electronic dashboard for you ebike measuring things like amps, watts, voltage, temperature etc.
  • Cycle Analyst = A widely used and well respected type of PMD. Go here for detailed information.

WHEEL/RIM (Where the rubber meets the road.)

All ebike kits include a hub motor laced to a front or rear rim. Most of today’s ebike kits will also include the tire. Standard rim sizes are 18″, 20″, 24″, 26″ & 700cm. (28″) A front wheel drive is by far the simplest to purchase & the easiest to install. They should not be used with aluminum forks or forks with shocks. A rear wheel drive will come with a narrow gear sprocket in case your sprocket is to wide. You should look for double-walled rims with properly tensioned stainless steel spokes. Many cheap kits use a heavier zinc coated steel spoke. All front hub motors require some type of “Torque Arm”. These can be anything from a flat washer with a bendable tab to a true to a true “torque arm”. See torque arms article for detailed information on the subject. Other useful information on rims and spokes can be found in Sheldon Brown’s article titled  Wheel Building.

There’s not much to say here. You will usually have an option for a thumb throttle or a twist throttle such as you find on a motorcycle. A twist throttle gives you better control thereby increasing your run time. Most of todays kits will accommodate the newer disc brake as well as the older V pull or center pull brakes. MAKE SHORE YOUR BRAKES FIT YOUR EBIKE KIT. Most ebike kits will ship with brake levers whether you need them or not. If you go with a “Regen” option you will need an upgraded brake lever with a switch.

WIRE HARNESS (The plumbing)
All ebike kits will come with one. One nice feature many ebike kits now have is a quick disconnect for the wiring that goes to the hub motor. I often retro-fit front hub motors with this option. It allows you to quickly unplug your front wheel & put your stock wheel & tire back on. All ebike kits have a quick disconnect for the battery pack. Between the two you can put bike back to it’s original condition which is great if your lifting bike onto the bike rack atop your SUV. (Do you really need a motor to cruise the boardwalk?)

BATTERY (The fuel tank) Go here for detailed information.

Lead-acid battery = The type of battery in your car. this 100 yr. old technology is very toxic, very heavy & has a short life span. They are so very inexpensive and can be found just about anywhere. Go here for detailed information.
SLA = Sealed lead acid battery. See above
PbA  = Lead acid battery. See above   Li battery = Lithium battery. Go here for detailed information.
Li-Ion  = Lithium Ion battery. See above or read about ALLCELL’s  new PCM Technology or for where to get them.
LiFePO4  = Lithium iron phosphate battery cells offering high power and energy density, excellent safety and life cycling. LiFePO4 is the safest and the most enviro-friendly chemistry make-up of lithium-ion batteries. Read “Electric Bike Lithium Battery Primer” for some very useful information on building LiFePO4 battery packs or here for detailed information on all lithium based batteries. See My Choice for Batteries for information on EZgo-Now’s new battery packs.
NiH = Nickel hydrogen battery. Go here for detailed information.
NiCd  = Nickel cadmium battery. See above
NiMH  = Nickel metal hydride battery. See above
BMS = A Battery Management System is required for the safe operation of any multi cell lithium battery pack. All BMS’s are not created equal. They effect both safety and performance so pay attention to what your getting.
PCM = A Protection Circuit Module is part of a BMS.

BATTERY CHARGER (The gas pump) Go here for detailed information:

Battery chargers are specific to both voltage and battery type. Many ebike kits will include a charger for SLA batteries even though the kit does not include any batteries at all. TIP!  PURCHASE YOUR CHARGER FROM YOUR BATTERY DEALER.

FREIGHT (you can’t get it from there to here without paying for this)

Freight can be a significant cost of your overall ebike kit. Many of these kits and battery packs are coming from China. In addition to these regular freight charges you have additional charges for shipping batteries as they are classified as a hazardous material. (you probably wouldn’t want 50 lbs of poorly packaged lithium batteries sitting in the cargo hold of a plane your riding in)


EV = Electric vehicle.
E-Bike = Stands for Electric Bicycle. Usually means that motor power is independent of pedaling.

E-bike conversion kit = A complete conversion kit will contain everything required to turn an ordinay bicycle into an electrictly assisted bicycle. Many of the super cheap E- bike kits require the buyer to make-up and install wires, connectors and mounting brackets. You’ll have to buy or have on hand zip ties, wire connectors and jumpers. Many do not come with a manual nor do they make any of the documents available on-line. Because of freight cost most conversion kits will make the battery an option or will not include it all. Finally a complete kit can take anywhere from 30 minutes to 1.5 hours. At the other extreme a bargain kit will take anywhere from 2 hours to the entire day and a trip or two to the hardware store. PAY ATTENTION TO WHAT’S INCLUDED. See Why E-BikeKit’s? or click the link below.

E bike Components

A good choice for e bikes & information.

HPV = Human Powered Vehicle.

Hybrid = This can be a confusing term because it is used to refer to different cases. Usually, it means one of the following three explanations1. Combination of a fuel engine with an electric engine.2. Combination of a mountain bicycle with a road bicycle.3. Combination of any engine with human power.
Moped = Low-powered motorcycle that can be also equipped with pedals.
LDV = Light duty vehicle.
LEV = Light electric vehicle.
PAV = Power assisted vehicle.
PABs = Power assisted bicycles.
PAS = Pedal assist.
Life Cycle = Total cost of ownership for the electric bicycle over it’s complete lifetime.
Recumbent = A bicycle that places the rider in a laid-back reclining position.

E bike Components, E bike Batteries

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Filed under: Electric Bicycle

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