New to e-bikes, bicycles or eletric stuff in general ?
Reading for days or weeks and still unsure of what to get ?
February 11 2011
I spend a lot of time and money reading and writing about E-bikes, and i get a lot of emails " what should i buy ? " with subject line : " HELP " .
When i first started with this hobby ( 2003~2004 .. ) , i spent weeks reading online on various forums and discussion groups, emailed vendors and did some research, i found it very confusing and not understanding what all the numbers represented, watts, amps, volts.. .. Batteries ?.. yikes.. I consider myself a failry smart guy, but, not having an engineering degree this voodoo of electrical lingo just drove me nuts...
Below is basic information, at least enough to get you familiar with what Electric Bikes aka : E-bikes are about.
First, Why do you want an E-bike ?
- Getting to work / daily commuting in rain or shine ?
- Recreation ?
- Exercise ?
- Looking for something new to do ?
Second, What are your expectations ?
- A little bit of help ?
- Short range ?
- Long range ?
- Fast, Slow, Quiet, Reliable, Cheap ?
. . .
It's usually a compromise, you can get some, but not all of the above.. it can be fast and powerfull but it won't be cheap ! ...
Cheap is possible but it comes at a price ! ( more DIY )
I separate this into 3 main groups, Low, Medium and High Power..
Group 1 - Low Power ( power assist )
If you weigh 200 lbs or less, live in a fairly flat area, are perfectly ok with 20 mph ( 30 kmh ) or less, with a range of 20 miles ( 30 kms ), honestly intend to pedal lightly to moderately.. 36v .. 500w.. 1000$ or less
Group 2 - Medium Power
If you weigh 200 lbs or more, have some steep streets and/or valleys to climb, like to go a bit faster ( like 25~30 mph / 40~50 kph ), not wanting to pedal much or any at all.. 48v... 750w + .. 1000$ ~ 2000$ depending on range and accessories
Group 3 - High Power
Cargo hauling, high performance, off-road, purpose built, this is the custom ebike group, sky is the limit when it comes to how much it can cost but power and performance come at a premium price, expect to pay at the very least 1500$ up to 3000$ for a " Complete custom... and there is no limit if you really get into it..
The large majority of first time buyers should aim for Group 1, these are the average starter kits, " 500w " or less..
36 volts is the standard entry level bike with a hub motor
( Below, a Direct Drive rear hub motor in a 20" rim on my E-BMX )
A hub motor is very quiet, generally , they are not all the same and some do make audible sound while others can be nearly silent.. Direct Drive motors like Crystalyte, 9C or Nine Continents, BionX, then geared hub motors ( the gears are on the inside, not visible ) like eZee and BMC , smaller geared hub motors are also available under the names " Mini-Geared ", " Bafang " , " Cute " , etc..
Brushless, Direct Drive ( no gears inside ) this is an X5 at 48v, the sound you hear is amplified by a cheap digital camera microphone in an echo prone kitchen , when outside you can barely hear this motor run.
eZee ( similar to BMC )
This was the last video i took on that camera ( i burn thru about one a year ! ) sorry for the yellow, this is a brushless geared hub motor, Click Here for pictures of the inside. It makes a bit more sound but not offensive in the least, once you get past 10 km/h the sound is gone and all you hear is the air rushing in your face..
Geared hub motors have one advantage over Direct Drive motors, they freewheel, meaning they cause zero drag when the power is not used. In the video, notice the wheel keeps turning after the throttle is off, vs the Crystalyte above that comes to a stop in about 10 seconds..
The drag caused by Direct Drive (* aka : DD ) is not that significant, there are many overly exagerated reports of severe drag and comments like " I would not want to pedal this without power, ever... ". i have tested many different brands and models and rolled down hills shoulder to shoulder next to regular bicycles, the heavier bike reaches the bottom of the hill first, every time ( coasting, without power applied )
9C / Nine Continents
This motor makes a bit of a Zing type sound when it runs, it's lighter than the Crystalyte X5, available in 20" or 26" wheels, for Medium power they are pretty good motors..
Video below shows the difference between " Instant Start " and " Pedal First " controllers.
These are just a few examples of what's available for hub motors, there is also another method to electrify a bicycle, and that's by using the chain !
" Cyclone" is the most common and known kit out there,
Below is a video shot outside, you can clearly hear the motor running, it is significantly louder than hub motors, still not nearly as loud as a gasoline engine but you are not fooling pedestrians, they will hear it as you buzz past them.
Click Here for details on the cyclone.
The motor itself is smaller and lighter than a hub motor, but once you add mounting brackets, freewheeling cranks ( so the chain can spin without you having to pedal, but if you do pedal, it hooks up, and you can pedal with the motor running, otherwise the cranks would be spun by the motor and force you to pedal 100% of the time.) the entire kit is as heavy as a hub kit.
A chain driven ebike (aka : Mid-Drive ) has the advantage of using the bicycle gears, this is an important consideration, hub motors and chain motors both have a variable speed throttle, but the hub motor is locked into a single gear in relation to the ground, being inside the wheel itself..
As of 2014, a few more mid-drive kits are getting attention, the Bafang and GNG brands come in various power levels from 250w to 750w, more power is possible but this is where most bicycle components start to wear out quickly and fail ( deraileurs, chains, etc.. )
What about " WATTS " ???
The average human body can pedal 100w worth, Lance Armstrong ( the bicycle elite ) can manage something like 400w..with a bit of doping... *cough..
A 200 Lb guy, on level ground, no wind, can sustain 20mph ( 30 kph ) on 300w or so without pedaling.
Add weight, hills, wind, and that power requirement goes up and up...
All vendors and electric related kits will have a Watt rating, do not be fooled by this voodoo of numbers, every vendor rates their kit differently and very often a lot of them sell the same parts using different names, it's all in the fine print and how they interpret the data... .. Quite a number of ebike vendors do not even understand what Watt figures represent to start with, they just sell a product they import and slap on an inflated marketing wattage figure to boost sales.
So take it with a grain of salt..
The real formula ((* Math alert !!!*))
Volts x Amps = Watts
These are things you will eventually understand...
Volts = Speed, higher voltage means a higher top speed. *( rpm )
Amps = Power, determined by the " controller ", bigger hose flows more water..
Watts = The result of Volts x Amps . . for example 36v x 10 amps = 360w
When you browse the internet for a kit and see " 500w " or " 750w " or " 1000w " ...this does not always represent correctly what you can expct from a given kit... you need to know about the " Controller " and it's " Maximum Amps " number. ( more on this later )
Battery Voltage !
An entire book could be written about batteries, but i'll stick to the basics, a battery pack has a range of operating voltage, hot off the charger a " 36v " battery is typically 42v, and when completely discharged will be at 30v, not zero.. this is imporant.
Remember this Volts X Amps = Watts ?
Well, 42v x 20 amps = 840 w
And 30v x 20 amps = 600w
A car with a gasoline engine will have the same power on a full or a nearly empty gas tank, but an E-bike will feel more powerfull on a full charge and fade away near the end. ( More on battery pack types later ) ...
A complete kit comes with 3 main things:
1- Motor ( obviously ! lol )
Hub motors can be Brushed or Brushless, Geared or Direct Drive, each have pros and cons but go with Brushless, these are more common, reliable, have no " brushes " to replace , ever, and a brushless hub motor can be either geared or direct drive.
The Brains of the operation, the Black Box that goes between the battery and the motor so you can regulate the power with a throttle.
A brushed motor does not technically need a controller to function, it could be hooked up to a battery with a simple ON/OFF switch, the motor only has 2 wires, + and - .. however this would be like having a gas pedal, permanently floored, having the option of slamming the transmission into Drive or Park.. no fun to ride !.. so you really need a controller and a throttle to make it a proper and safe ebike.
A brushless motor canot work without a controller, the motor has 3 thicker power wires and most motors also have an additional 5 smaller signal wires ( Hall Sensors ) that allow the controller to run correctly from a dead stop and at full power.. there are brushless " sensorless " controllers out there ( Video above ) , they can be unreliable at very low speeds and some of them require you to pedal and get the motor spinning before the throttle responds.. I highly recommend the sensored types over the sensorless.. *2014 update, sensorless controllers have improved greatly, some controllers now function with and without hall sensors.
Different controllers have various features, but all of them do one main thing, they let the rider adjust how much power the motor is allowed to use from the battery. Depending on the model they impose various restrictions, like
- Low Voltage Cutoff / LVC - ( once the battery voltage goes below a certain number, it shuts down to prevent over-discharging the battery )
- Maximum Amps ( most are 20 amps max, but they are available with higher power limits for bigger jobs., remember, volts x Amps = Watts )
- Operating Voltage ( most 36v controllers can also run on 48v, for more voltage you need a controller with compatible components )
There is alot of stuff to know about batteries, a lot, expect to pay as much for a high end battery as the rest of the kit, sometimes more.. much more...
How far you can go on a charge is determined by the capacity of your battery pack, all batteries have an Amp Hour rating , " Ah " , 10ah and 36v will usually provide 20 miles ( 30 kms ) .
10ah means 10 amps, for one hour, or 20 amps for thirty minutes
12ah means 12 amps, for one hour, or 24 amps for thirty minutes
20ah means 20 amps for one hour, or 40 amps for thirty minutes
Entry level ebikes use SLA ( Sealed Lead Acid ) , the most common are 12v-12ah ( 12 volts, and 12 amp hours ) each, and weigh aprox 10 lbs per piece, so a 36v battery pack is made from 3 of them.. They must be charged at all times, after every ride.. or they die quickly ( one season.. or so )
Typically SLA lasts 1 season, sometimes 2, but that's pretty much it...
video of an SLA pack build :
Next up from SLA is NIMH and NICAD, these have been around for a long long time, not as common these days with all the lithium options on the market but still can be found.... not much to say about nimh and nicad... they work, suitable for low to medium power, lighter than SLA, and they take up less space, do not need to be recharged right away after a ride... lithium is better.
Lithium, if you spend any amount of time browsing thru my Projects Page you can read about some of my lithium adventures, i've been using this chemistry since 2004 and am convinced that it is the way to go.. Lightest, most powerfull, compact, quick charge capable !
36v 12ah SLA = 35 lbs
36v 12ah of nicad = 20 lbs
36v 12ah of Lithium = 10 lbs or less !!!
Hands down, a hub motor kit is the easiest kit to install, very low maintenance ( like, none ) , quiet and efficient on most terrain..
Chain drive setups are another option, like the Cyclone for example, they do require more skill to install and often require a fair bit of DIY creativity and a " pile of parts " type of person to make them work... needs maintenance and are louder... However, because they use the mechanical advantage provided by the bicycle gears, they have the ability to use a slower gear to climb hills at a slower speed using less power.
So , after all that, how do you decide what to buy ?
The first thing to consider the bicycle, use one you have ? or buy another one ? or even buy one pre-built ?
Good deals can be had on ebay and via a series of other online sources, my projects page outlines quite a few of them as well.
When selecting a bicycle, consider the following :
- Dropouts, this is the part of the bicycle that the motor will bolt to, at the axle, you need a frame ( rear motor ) or fork ( front motor ) with adequate strenght to handle the forces involved, flat, thick, with a 10mm slot ( most common)
Below are examples of proper dropouts to look for :
Some front forks are made of soft aluminum or " cast " with "lawyer lips " or a spot for a quick release hub to recess into the fork and prevent the wheel from falling out if the quick release lever ever got loose... these recessed dropouts can be a problem for hub motors.. they prevent the motor ( nuts and washers.. ) from securely seating flush with the metal, avoid this at all costs..
Below, the type of thing you want to avoid !
Do not install a front wheel hub motor on a fork like this:
- Full suspension or not, big box stores sell really cheap full suspension bikes these days, and surprisingly they are ok for the average conversion with steel frames and strong dropouts, but for the same or similar amount of money you can get a better quality non suspension bicycle with better components. Cheap suspension is usually springy and act like pogo sticks, they do soften the ride but make rear racks hard to find and difficult to mount unless you bolt them to the seat post....
- Brakes !!!.. some kits come with disk brake mounts, some do not, regardless, make sure your bike has good brakes, with higher speeds and the added weight of the motor and batteries, the brakes will have to work harder and wear faster, V brakes are ok up to 40 km/h, over this you really should look into disk brakes..
- Bicycle types ( frame ) .. if you are a 6 feet tall + you likely do not want a BMXfor example, but if you have to lug the bike into an office and hide it in a closet you might want to look into a Folding Bike, for long range commuting a full size mountain bikeor a recumbent might be better, or even a trike !..
There are also pre-built options, for those who prefer not to get their hands dirty, the big W stores, and even Canadian Tire sells pre-assembled schwinn and currie bikes, these range from 500 to 1000 $ with 250w to 500w systems, honestly, i've looked them over a number of times and if the bicycle happens to be your size and you are on a limited time and budget they can be a starting point, i can't knock a complete bike for less than a kit in some situations, but know that you are on your own when it comes to after sales service, big box store guys usually know nothing about electric bikes and " Bring it back for a refund " is all the support you are likely to get.... you can also get electric scooters that have " E-bike" stickers, like these :
Below is a common " ebike " scooter , it's certainly not a bicycle as the pedals are removable and even when attached are completely useless ( and sometimes dangerous )
or not quite as scooter type below,
It's a matter of personal taste and what you need it to do for you.
There are a number of quality pre-built ebikes on the market.. expect 1500 $ +
For example, my Ultra Motor , A2B Metro:
There are also a list of other good bikes out there if you have that kinda cash !!.. like optibike $$$ .. and less expensive Pedego... etc..
If you want to get into the 2nd group, " Medium " power, you move up from 36v to 48v, most ebike kit vendors do not advertise this, but just about all 36v hub motor systems will run on 48v without any modifications, you just use a higher voltage battery pack ( exception for kits that have LED displays or lights, green, yellow, red battery indicators those are 36v only..)
Remember, Volts x Amps = Watts
36v x 20 amps = 720w
48v x 20 amps = 960w
The controller only limits " amps " so whatever voltage you plug into it will determine the watts, more volts at the same amps produces more watts so you get more power and more speed !
When going to medium power, go with a rear wheel motor, too much power on the front wheel can be very dangerous, if the motor breaks the front fork, it likely will result in a nasty crash !!!.. rear part of the bicycle frame is stronger and with proper " Torque Arms " can tolerate higher power levels.
Then, High Power !
When 48v is not enough and you need/want more, power that brings on the " Ev-Grin "
Below is my nephew, for his 4th birthday i built him a hacked minibike on 24v nicad, i'm told he loves it !!!
Going to the extreme end of the scale, you get into custom high-powered systems, this is more complicated and expensive, also can be dangerous if done wrong. **it's also dangerous when done right lol..
Anyone who has been around long enough will remember the " Dirt Monkey ", a guy from the UK was one of the first to apply high voltage to a hub motor laced into a small rim for off-road fun, this was my first experience of " Whoa.. i want one of those !! "
My first run at 72v was on a folding bike, the Downtube
About 5 seconds with the throttle on and i was hooked, but it was clear right away that high power requires a strong bike frame, and the folder was not it !!..
My Chopper for example, at 72v and this is not it's max potential, i've had it running on 80 amps and the acceleration is motorcycle like fun, in complete silence.
Then there is the chain driver version of going overboard , The RC bike !
As you can see, the RC bike is loud, and fast, and complicated.... and expensive to build over the course of a year, and it's not even completely done... customs never are lol..
Always wear a helmet, and gloves, equip your bike with Lights ! and respect the rules of the road, just because you can move like an athlete does not make you invincible. If you build a medium to high powered machine you should move up to a better helmet, and better gloves !!!..
Some parts of the world have limits on power, these primarily apply to vendors and retail stores, the garage guru can always customize and get away with it as long as he does not make a jackass of himself in public .. again.. wear the safety gear and play by the rules of the road...
Cars are not restricted to posted street speed limits, some sports cars go well beyond double and tripple any possible posted speed limit yet they build them.. and ride them on the streets... i feel that this is no different.. Don't act like an idiot and you likely won't be treated like one !.
So if you made it this far, you should now have an understanding of what to expect from an ebike or conversion kit, if you have questions or need some help or if i missed something you would like to have added, register on my forum :
" One test is worth a thousand opinions."- *R.Fechter
Also see F.A.Q