250 watt hub motor E-bike; Is it Enough?

August 8, 2012
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250 watt motors are the most used motor on commercially available electric bikes. They are popular in Europe (and Asia) where in many countries there is a 250 watt power limit on E-bikes. Because millions of these 250 watt motors have been made for the European and Asian market, the cost to buy them from the factories in China is low, but at the same time it is a motor that is proven to be reliable and efficient.

The wholesale price from China for a geared hub motor is around $60 before shipping. In comparison, a larger 600 watt geared hub motor such as the BMC will cost $250 wholesale from China. An ultra-affordable 250 watt motor makes it possible for an E-bike manufacturer to sell a decent (but low powered) electric bike, and still make a nice profit.

The 250 watt hub motor comes very close to being a  perfect piece of E-bike technology, cool looking, lightweight, reliable, and cheap. It could have been the very best way to make a bicycle into an electric bike. However….the only caveat is the simple question…is 250 watts enough? If 250 watts is enough for you, then this might be the ideal power plant for your E-bike.

Small is good

When it comes to computers, phones and hub motors, small and lightweight is good.  As electric bike technology has improved over the years, engineers have figured out how to make a smaller and lighter hub motor. The 250 watt hub motor is an evolution of hub motor technology, and is in fact a beautiful piece of E-bike porn which  made #4 on  our top 10 list of E-bike Porn. It would in fact be a perfect electric bike solution if it was possible to pump more power through it reliably. (Check out some examples of beautifully built mountain e-bikes utilizing 250 watt hub motors.)

Quietness and Ride Quality

250 watt hub motors make very little noise…just a barely audible hum. Because they are almost silent they are like a magic carpet ride. Because they are so small (and not powerful) the power will come on smoothly.

What does a 250 watt hub motor consist of?

Most 250 watt motors are geared hub motors, meaning they have a planetary gear reduction so that the motor spins at an optimal RPM. This makes the motor more efficient than a simpler direct drive hub motor. At 250 watts, the planetary gears means a more torquey and more efficient motor. In this motor pictured below, you can see the planetary gears which allow the motor to spin up to 5 times faster than the wheel. Since electric motors love fast RPMs (more efficient, more torque, and more reliable) the planetary gear allows the use of a smaller and lighter motor, with the same power output of a larger motor.

Power to weight, the geared hub motor is much better than a direct drive hub motor (read our story comparing geared and direct drive hub motors).  Although a few companies make a 250 watt direct drive motor (such as Bionx’s 250 watt motor, the same motor that goes on the Smart Bike), we strongly suggest that if you buy a bike with this size of motor that you opt for the geared hub motor which is lighter, smaller and more efficient than its direct drive counterpart.  Like most hub motors of today, most of the 250 watt motors currently on the marketplace use highly efficient brushless motors.

 

the inside of a Bafang 250 watt motor (8fun)

 

Advantages of 250 watt motor

  • Lightweight (6 pounds) THe biggest advantage of these 250 watt motors is they add very little weight to your bike. 6 pounds is the same as a Kryptonite U-Lock. To compare, a Crystalyte hub motor tips the scale at 15 pounds. Weight in the wheel that you can really feel. Even a pound less makes a big difference in the feel of the bike.
  • Stealth looking. You can’t beat a 250 watt hub motor for stealthiness. Even when installed on the front hub they are hard to identify. They look almost the size of a standard wheel hub. In the rear wheel they hide perfetly behind the rear sprocket and disc brake.
  • Free wheeling. Geared hub motor free wheel just like a regular bike (but no possibility of regenerative braking)
  • Easily fits on front or rear hub. Because 250 watt motors are so small, they can easily be mounted in the front or rear wheel. Because they put out so little power, you don’t have to worry as much about this puny motor snapping drop outs like you do on the more powerful set ups.
  • More range. 250 watts is an extremeley efficient wattage to operate at, and forces the rider to provide input. Therefore 250 watt bikes will get a long way per battery charge.
  • Super reliable. Because 250 watt motors have been mass produced and tested on a mass market, they are super reliable. And should give you years of trouble free use. If one breaks no problem, they are cheap to replace.
  • Cheap purchase price

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when is 250 watts enough?

Lets say you do all your riding on a paved flat beach trail. And in beach tradition you like to cruise while sipping your virgin piña colada with plenty of your own pedal input, so you are getting exercise…a 250 watt motor might just be your cup of tea. Lets say you ride on hilly terrain but just want a boost to smooth those hills out, and you don’t mind pedaling hard up these hills and providing plenty of your own pedal input…250 watts might be all you need.

Also the less you weigh, the more likely a 250 watt motor will fit you. If you are thinking of giving your 90 pound 10 year old an electric bike for Christmas, 250 watts is plenty of power. For a 300 pound rider, you really need to look at 600 watt motors and beyond.

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A 250 watt motor and hills

definitely more than 250 watts….try 2000 watts on a mid driven m55

 

where you will feel the deficiency of a 250 watt motor is when traversing hills, especially off road. Hub motors are generally inefficient when climbing because they are usually geared for flats. When you hit a hill, that 250 watt motor is really going to have to work to pull you up, and if you your part and vigorously pedal-assist it, you can easily burn that little motor out. Generally since efficiency is so important when limited to 250 watts, if you have a hilly commute it is better to with a 250 watt mid drive which are extremely efficient and great hill climbers despite their minimal power output. (you can climb in your bike’s granny gears).

250 watt motors are less reliable than larger motors

Because 250 watt motors are so small they tend to be more fragile than the bigger and heavier higher wattage hub motors.  Also most people ride 250 watt motors at full throttle all the time, where as with larger motors you can ride them at half throttle which is easier on the motor.

A 250 watt motor is not more efficient than a larger hub motor

Lets compare a 250 watt motor with a 500 watt motor. If you limit the 500 watt motor to 250 watts you will not see any difference in efficiency. This means a 500 watt motor can serve as both a 250 watt bike and a 500 watt bike depending on your needs and wants. Most electric bikes have some kind of efficiency mode where power is limited, so that you can switch to half power with the flick of a switch.

250 watts forces you to be a miser

When the maximum wattage you can burn is 250 watts you will naturally be super efficient, since at 250 watts you will rarely find youself in situation where you have too much power. For most situations, 250 watts is “just enough” to travel at a moderate pace. Without the temptation of having extra power on tap, you will always use a maximum 250 watts….turning you into an electric power miser whether you want to be or not. It’s hard to get in trouble when riding with only 250 watts on tap.

 

World’s smallest e-bike, read about it here.

 

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250 watt E-bike allows a smaller battery pack

 

A 250 watt motor allows manufacturers to offer a smaller battery pack and get away with it. A great example of this is the Faraday electric bike which as you can see uses a 250 watt geared hub motor in the front, hidden behind the front disc brake. This bike has a meager 110 watt-hour battery.  Can you see where it is hidden? The battery pack is actually built into the frame tubes of the bike. If you put a 600 watt hour motor on it you would only get a pathetic 10 minutes of wide open throttle before the battery died. With a 250 watt motor, the Faraday is able to get an acceptable 25 minutes of wide open throttle before the battery dies.

250 watt bike gets you into shape
250 watt bikes means less cheating and more exercising. Many times when you have plenty of power on tap you end up being lazy and using more of that power than you really need. A 250 watt just give you enough power to help you up the hills, speed you up on the flats and keeps you totally honest.

250 watt bike in the USA?

The real problem with a 250 watt powered bike in the USA is that you are allowed to ride up to 750 watts legally in the USA…why settle for a bike that was built to adhere to European standards? You can always have a switch on your throttle which limits your bike to 250 watts and be just as efficient as the smaller hub motor…why not have the option for 500 watts or 750 watts when you want it? 250 watts is not enough to give you serious help up a hill, where 750 watts is. Even on the flats, you will be hardpressed to get to 20-MPH on a 250 watt bike without pedaling hard.

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DIY 250 watt conversion

This custom built Power in Motion bike has AWD 250 watt motor in both front and rear…super sweet.

 

250 watt bikes are super easy and cheap to build. You don’t need to stress as much  about torque arms etc,  because 250 watts is not strong enough to snap most drop outs. You don’t need as big as a battery, even a 250 watt hour battery will keep you moving at full throttle for an hour.

Types of 250 watt motors

There are 3 main manufacturers of 250 watt hub motors at this moment. Bionx, Bafang, and Cute. To read about these 3 motors read our  story here.

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250 watt motors and E-bike manufacturers

 

Many major manufacturers are opting to use the 250 watt motor for upcoming bikes that otherwise would be pretty exciting. The list of bikes included the Smart Electric Bike, the Specialized Turbo, the Faraday electric bike, and the Grace E-bike. These manufacturers have decided that 250 watts is enough.

So is 250 watts enough?

I really believe that 250 watts is not enough power for most consumers in the USA. It is refreshing that  electric bike manufactures in the USA such as Currie, Pedego and Stromer are offering 500+ watt bikes in their product lines. You might think a 250 watt hub motor is enough, but once you test ride both a 250 watt bike and a 500 watt bike together, it is hard to settle for the measly 250 watt hub motor. However, if you really are the type who will never need more than 250 watts, its hard to beat the stealthiness of a 250 watt hub motor bike.

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Hot rodding  250 watt motors…to 1000 watts

Check out the rest of this builders beautiful 250 watt bike builds here.

 

Some hotrodders, attracted to the small size and low weight of the 250 watt motor, but not satisfied with its puny power output, have over volted them and run as much as 1000 watts to them (read our hot rod primer). If they could do this reliably, this could be the E-bike motor solution we all have been waiting for. However cooling is a real issue with these small motors and its easy to strip the nylon planetary gears. Once hotrodded, these motors become  fragile and must be run with care and common sense when it comes to throttle input.

Therefore they are not very popular platform for modifying.  However check out in the above bike how the tiny 250 watt motor fits nicely into the mountain bike frame that a full size hub motor could not dream of fitting.  For another great example of a mid mounted 250 watt motor check out this forum thread.

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2WD?

Most of these motors get 250W by using 36V (which we agree with, 24V is a waste of time), and they then limit the power with the controller capped at 8A (36V X 7A = 250W). Here’s a tip, you can traise the amps to 10A to get 360W, and I recommend adding a temp sensor to keep track of how hot the motor is getting. In that situation, you can raise the amps to 12A (36V X 12A = 420W), and as long as you don’t take it onto a long and steep uphill, it should only get warm. But…why not use TWO of them?

These motors are small, light, stealthy, and cheap. If you already have one, why not just add a second one, instead of selling it and buying a bigger hub? Get a second 250W hub of the same make and model, along with a second controller that is the same as the first. You only need one throttle and one battery.

Plus…if you add temp sensors to keep track of the internal heat (keep it under 93C/200F), you could raise the volts to 48V and run both of them at 10A…for a combined 960W of 2WD! If you put a pair of saddle-bags over the rear cargo rack, nobody will even know that you have a second motor. Especially since these small motors fit well between a rear brake disc on the left and the wheel sprocket on the right.

To get an idea of what a single unit of these little motors can do when hotrodded, check out this video:

 

 

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Written by Eric, August 2012

Eric has been involved in the electric bike industry since 2002 when he started a 6000 square foot brick and mortar Electric Bike store in downtown San Francisco. He is a true believer that small electric vehicles can change the way we operate and the way we think.


84 Comments

  1. It’s quite hard to find out where the limits are and how hard these motors can be safely hot-rodded. There seem to be several anecdotal stories of the Bafangs being run at 36v-20A with no problems for ~750w. That may depend on the usage cycle and local temps. Long hills in 100F heat will perhaps still kill them. The commercial bikes that use these, even those that are nominally EU legal seem to be configured for more like 500w given tolerances. eg ~40v battery, ~12A max current. Quite a lot of people have achieved this by adding solder to the shunt in an EU legal controller, again with no real problems in the hub.

    The other problem is that they are typically geared for a nominal EU limit of 25kph/15mph. So perhaps the answer is a 36v motor run at 48v-15A That way you get the higher no-load speed and the same ~750w. It may not actually pull the full 25mph but at least it will still provide assist well above 15mph.

    The nice thing about the latest rear drive motors is that they pretty much disappear behind the gear cluster and disk brake and they’re light.

    It’s also hard to find real experience of the Cute (Q85, Q100, Q120) vs the Bafang. The Bafang design looks more robust and I don’t really trust the way the Cute doesn’t have a full through axle but is bolted together in 2 pieces. The Cute’s dual gears also don’t look as strong. But of course none of that may actually matter.

    Like you say, the holy grail has got to be a neat mid-drive that avoids all the potential problems. Packaging is still really hard though in a conventional frame.

  2. How can geared hub motors with plastic gears and bearings that require lubrication be more reliable, compared to a direct drive, no moving part motor? Not to mention the noise created by the gear train compared to an almost silent direct drive motor. I like the slower turning, simpler design and regenerative braking of the direct drive waaay more than complicated high RPM, high wear, high heat design of a geared hubmotor!

    • if you want regen with a geared hub motor open it up and weld the freewheel in position, that’s what i did (take it out first!) the high rpm means less heat as it is more efficient than a gear-less hub. also if you want more speed from a low wattage motor run it from a higher voltage current limited supply

    • A killer factor is air freight. DD bubs are way heavier. Weight is not a good look on the bike either.

  3. @magic carpet: I’m running a 250W Bafang rear hub in my trike for one and a half years and slightly over 6000km now. Used at its rated voltage (36-48V) it’s very reliable, sufficently quiet and stone cold. Good climber for its size and weight. The motor up for service but I abused it with 60V+ for some time.
    Sure a direct hub is quiter and probably more reliable but if you are power restricted to 250W by law like us Germans direct drive hubs are no real option and a pretty lame experiance. At 48V/15A and about 600W output my little ‘250W’ geared Bafang is equal in speed and torque to a 1.5kW DD bike.

    • Thanks for the post Marc. I am really thinking about hot rodding one of these myself and your insight helps.

  4. 250W is not enough and neither is 750W if we every want to see electric bikes seriously take a dent of automobile travel and commuting in the U.S. It should be legal to have a bike that does at least 35mph (safely) to keep up with in-town traffic, be faster than a pedal bike (or whats the point), and powerful enough to get rid of the pedals all together. We finally have the technology to do so and we’re not allowed to legally utilize it. Its like if Henry Ford were required to keep a horse teathered to his first cars. There will always be a market for cheap, low-power pedal assist ebikes for recreational use and strolls in the park, but we also need to capitalize on the ever increasing performance of motors and battery technology.

    • well said. I agree completely

    • Yeah, but it is only illegal to ride without a license. They are still legal like a motor scooter, so you have to have a driver’s license and register the vehicle. So, it is still legal to have a 2000 Watt bike, but you have to jump through a few more hoops… just like you do with a car or motorcycle, but… with the much lower cost of entry and ownership of an EV bike.

      • Yeah, and pay the govt money to use it in the form of a drivers license, tags, and insurance once you become a scooter/motor bike. All I want is to be left the hell alone and the govt to shove everything up its ass and stop taking my money to send to other governments who hate us. Let me ride and be free not spend 4 to 6 dollars a day in just bureaucratic theft.

        • I don’t disagree with the gist of your post but the reality is that roadways and paths don’t build themselves for free. Are we overcharged for these niceties? Is there room for improvement of the process and lowering costs to end users? You betcha (but nothing is ever for free).

          • Well, if you saw the lack of paths here and the roads here are in a very horrible state I see nothing the money taken from us has done for any good of the people. If you tax people then you need to shell out to the people and I still believe the first priority of any govt is to take care of its own citizens first. Health, happiness, and the general welfare because if you don’t have those you honestly don’t have a country or at least not for long.

          • it used to be free when all we did was build to survive! now it build to pay the rich to fund the richer like wtf?

      • sir – & others

        well put good points

        but just sayin

        firstly, to the “somebody gotta pay for paths” guy – well yeah, but as a related thing, have a look at google maps of a city you know – me sydney – hurstville

        the older areas are lovely – sensible webs of access ways.

        the newer areas show up as huge chunks of land penetrated by cul de sacs. no passage accross. Maximised land usage for developers, blow the residents

        Worse, existing passages are being alienated from the public in an avalanche Yet i have not heard remarked on, perhaps its even been applauded Mostly I am thinking high street footpaths.

        Now anyone can extend their business on to the path to the point its single file for thee unencumbered. They just draw a line on a plan that takes no account of other obstructions. I pity pram jockeys now.
        At my very busy local shops, once wide paths are now one lane.

        remember night soil lanes, mostly grabbed entirely. I know of a great path that was simply stolen by adjoining landholders – (mosman 2088 – upper avenue road/mosman st to reid park)

        re your post sir,

        its still a damn good deal – free as a bird legally if you dont get greedy about power & speed

        Some points:

        Folks, its not about power, its about power to weight.. say the average car is 1. 5 tonne. Its doable for an affordable MTB bike to be 15 kilos. thats 1% of the vehicle weight. Put a 70kg person alone on that & its damn zippy up to 40 kph or so when wind makes it pointless to be extravagant with power.

        now if you had a serious urban commute task, add an ebike kit to a dirt cheap but good used ~12kg drop bar roadbike and maybe you only weigh 60kg, then there is your car speed get to work bike. Dont be fooled, I have found them to be very strong – carried slabs etc.

        The mountain bike is a pretty serious bit of engineering honed to perfection by perhaps a billion made.

        Face it, ebikes do stress a bike unlike a pedalled bike. Potholes at speed, extra mass at higher speed..

        I have a 350w mid drive 24 speed alloy mtb and with just my ~75kg its pretty fast and I can mostly join the traffic

        Its great but I think 36v 350w is a pretty balanced machine. If i want to go fast, I travel light. But with the mid drive & gears, i can haul the shopping up steep hills – no pedalling (its often not possible when loaded so a very low range is good, just in case)

        I agree its a pity some allowance cant be made for apps like pulling a trailer. Its not the power, its speed which is scary

        if folk can speed they will which inevitably leads to fines and calls for licensing.

    • It does seem to me in my dotage they among the flood of dross that comes out, occasionally I think, thats awesome, wish they had that when I was a kid, then they ban it.

      vested interests can usually find a safety angle to find a sympathetic bureaucratic ear.

      Those little gas stoves using gas cans – wonderful – banned I think due to some meth labs maybe.

      Dogs – wonderful but may as well be banned given degree of difficulty & expense of harassment.

    • yes you are right, my bike is 1000w and its a DH bike so it looks motorbikeish, i feel illegal all the time on it, in a worse case scenario they could take my ride, take my car license, fine me etc, sure in reality i should be able to avoid this but its not a good feeling feeling like a criminal when im riding a effing bicycle!
      sure there should be limits, like 30mph max, and they should see if things get out of control, like too many people use them? is that a bad thing? or too many injuries happening to kids using them, then make laws gradually, but they went straight in with 250w max 15mph! capable of 15mph max! we should be encouraged to ride e good e bikes.

      • even a fat, diabetic, asthmatic could pedal faster! Its just too slow! germany allow up to 28MPH this kind of speed i MIGHT consider as it matches mopeds but isn’t one. I would definitely agree with it being legal limits of between 28-40 that is my personal preference for comfort and safety when riding. it feels fast and isnt too bad at coming off…I did once, slipped brakes when it was raining and slid into curb lol. hurt a lot; learned my lesson got back on it and rode that corner differently everytime lol.

        • moped are motorised bike…or used to be…now the name is closer matched to a motor bike in build design so that makes bicycles once again its own league. so shouldn’t we be able to use them with some power enough to match our pedaling speed not the speed of mobility scooter lol(although they are limited to 8MPH in the UK)

          • old age pensioner shave waited all their life to get their retirement….now they can spend it on mobilty scooters…aand waiting for them to carry them to the shops REAL SLOW -_-

        • You might think more speed but actually speed kills…when your on tracks/pavements with walkers / families. ..its just far too dangerous to do these speeds..it’s ok to say but I wouldn’t. ..but others would !…15mph for an ordinary bike is all that the tyres brakes and frame is really safely up to. As for bigger motors your forgetting crash helmets and all the safety equipment motorcyclis use then it’s actually not so free…what’s more the wind gets colder the faster you go…so no t shirts…the argument goes on and on..

          • Need to watch more Russian Dash Cam compilations. 1000 examples of ways that speed kills.

      • if you’re sensible only a bored officer will pull you over. if they even notice the quietness of electric power. I know my bike needs some improvements…i need better lights…luminous paint strips down it as it is matte black; moving the controller somewhere less obvious(cables hanging out look ugly) and adding some indicators which exist BTW, try looking at the “meilan X5”; then i would feel safe enough to drive around personally; one thing you can never help is the elderly complaining to get in the road when your in a bike lane lol; must happen to everyone at some point.

        • should have seen the face of the race bike guy i overtook without pedalling….absolutely worth letting him overtake FIRST for it heheh; doobadee doo doobdedoobde doo is what i was thinking when passing…he was in full lycra suit with expensive race bike and i overtook him with cheap chinese elctronics and a cheap £100 bike frame when new that one of my neighbours threw away hehee even better

          • tbh he probably thought i was “cheating” bicycling lol

    • Those are called scooters.

  5. i’m thinking that if you put an extra piece of aluminum around the motor and dig channels in it for non-conductive oil to flow through due to centrifugal/centripetal force that sufficient cooling of the windings would not be too difficult. some r&d is in order i think. wish i had the time and funds to do so. oh well, guess i’ll have to wait for someone else to patent my idea and charge me out the wazoo for an example. 🙂

  6. 250 watts is enough if you don’t have a driver license and your bike must be classed as a bicycle. If you want to drive a bigger vehicle, 250 watts may not be enough. I got a bike with this effect and I’m happy of it. Sometimes my dad tells me that I will weight more and more and 250 watts won’t be enough anymore, he also tells me that 250 watts is enough when I weight up to 75 kg. The Twikes have got an effect of 6 kilowatts and I think that even when that’s a car it is enough. Thanks to the low effect the machines getting it save more energy. The Swedish law says that you don’t get to have a bike with a bigger motor than 250 watts if it has to be a bicycle. But you also have to get a pedal assistent system (PAS) if your bike has to be a bicycle, without it the law says that it’s a moped and the driver of this kind of bikes has to get a driver license and the helmet. This law is not just the Swedish law, nearly all countries in the European Union have got the same law.

  7. Surely if you have a spinning hub it’s possible to attach some cooling fins within the spoke area or use shaped spokes to dump the motor heat and prevent overheating. I find 250W just fine for my commute, but think the law should be similar to other forms of transport with a speed limit for the electric assist but no restriction on power.
    If a “larger” person wants the power to climb a steep hill without peddling then that should be fine up to a maximum speed.

    • Good point.

      • But maybe the larger person need to pedal some more to get in shape.

        • Or, maybe the larger person is already in shape. At 6′ 4″ and built like an NFL linebacker I’m not going to get under 220-230 Lb without amputation.

          We all get what we get in the genetic lottery.

          • Cooling fins may help – a little. The hottest part of the motor isn’t thermally connected to the hub/wheel in a geared motor. Some cooling may be achieved by forming fins into the non-rotating plate of the hub especially if oriented horizontally to maximize airflow when underway.

          • dunno exactly how to maximise heat transfer but fins for the overheating ebike hub motor are right there handy – the spokes.

            surprising its a problem

            the whole wheel is an excellent heat dissipator.

            not for me, but if you loosed & retightened spokes, perhaps the heatsink paste they use for PC CPU heatsinks would help – same problem.

            When the hub is hot, would be good to touch test spokes to see if they are hot also – are they carrying heat away?

          • Not much thermal mass in spokes. I could imagine an AL wheel that looks like the BMW plastic (?) wheels would dissipate the heat better.

          • Nor much mass in the fins of a cpu heat sink of an air cooled engine either, & they are not built for strength like spokes. I sure disagree for heavy gauge spokes. u could even get warm rims maybe.

            Main issue i suspect is the main heat is in the central stator, not the rotor.

          • Drawing air through the motor?

  8. i want to pull 250 kg of an electric car, how much watt motor is sufficient at speed of 60 km/h????

  9. I have used an 8 fun motor on my converted Giant full sus bike for 2 years. The first was a front wheel kit and then I built a motor into the back wheel.
    As I ride the Welsh red and black trails I found the front motor terrible on the suspension hence the change to back wheel.
    I am 67 years old and weigh 100 kg. 250 watts is enough for 2 hours trail riding if you manage the power sensibly.
    The main advantage for me is that I did get fitter more quickly because I can ride the trail continually using less effort; this in turn meant that I only used the maximum settings on the really steep bits.
    Power management is the key here – find the optimum speed for the motor and the battery will last a lot longer, especially on a hot day.
    At no time have I burnt out the motor or stripped the nylon gears.
    There are 360w and 500w versions by the way but these need the relevant controllers and of course they run the battery down quicker.

  10. Nice..

  11. 250W is more or less only a sticker in europe. It’s the maximum continuous power but there is no definition on contentious power for pedelecs. The peak power is not regulated.

    Typical DIY kits sold as 250W kits (Bafang, XinFeng, Cute,…) use 14A controllers at 36V which translates to 500W of battery power.
    a BionX SL250HT or PL250HT that is sold as a 250W motor in Europe is able to draw up to 30A on a 48V battery which translates to 1400W of peak power form the battery. That’s far from 250W and still considered legal.

    Of course its difficult to use that power for climbing up longer hills because those motors will overheat, but the peak power still is far from 250W. a Bosch middrive will draw around 500W from its battery climbing hills and it can do so until the battery is dead…
    That’s more additional(!) power to you than the best cyclist in the world could produce for that duration.

    There is also the legal option of having “500W” and a speed limit of 45km/h with s-Pedelecs which require insurance and a drivers license, but no helmet (so far). DIY is not possible in that case.

    If you are not able to go uphill with “250W” of extra power from a Bosch middrive with your bicycle(!) you shouldn’t go there anyway. People have climbed ski-jump ramps with Bosch bikes.

    If you want to go 60mph with a electric motor on public roads you will need to buy a electric motorcycle, buy some insurance and have a driving license for that.

    I think this is quite ok. Something with a 5000W motor is not a bicycle and should not be able to run without license plate and insurance. you will agree if you or your children will be hit buy such a biker with no insurance.

    No matter if you life in the US or Europe a DIY 5000W bike will not be legal.

    • 60 mph with bicycle brakes? And bicycle lights? I suspect the gov’t will have an opinion on that… 😉

  12. hello, i seen a video of a kid building an electric bike and thought wow that is kool so i told my son and he wants us to build one for our family. so my son and i are building a quad-bike to fit 4 people and carry beach gear or fishing gear. we estimate the total weight to be about 600lbs. with bike, riders and gear. i see that these 1000w 48v hub motors are pretty popular but we cant figure out if that would fit our needs. can you guys help me be the hero dad cause i cant afford to get it wrong with a motor that wont work…

    • 500W per 150lbs is plenty to climb hills. So I guess if you have 4 of those 1000W you will be fine

    • And you’re going to load that on bicycle tires, placing the turning forces on spoked rims?

      • i thought the same thing, that regular bicycle rims might not be able to handle the turning forces either but i am learning this as i go and hoped that the community would have the answers to any problems that come up. as well as sharing any successes and failures i expirience with our project

        • see my comment above

        • This out of date but here are some YouTube search for you:

          “4000 Watt electric car with 4 wheel drive. Maker Faire 2014”
          “Wesll Corp leaning suspension”
          “Contes Engineering Athos Prototype Construction and Testing”
          “PodRide pitch v1,1”

          Maybe that will inspire you and off proof of what you are imagining is not impossible. Not necessarily easy either.

      • Hi, I’m 70kg with 14 kg bike on front wheel drive 1000W 48V. I’m sure that the wheel with good construction (36 spokes, alloy double wall rim, mine is 622-21) will work. Mine has been two years and still going well, taking down many Scottish hills

      • Can allways use smaller wheels. Scooter wheels, notmal 26″ are very strong & a have a vast user base for a cheap parts ecosystem

        Bike wheels come in all sizes & motors can be spoked to most all of the sizes. Kids bikes, scooters etc. Spokes are not compusory.

        Maybe revert to older but heavier steel rims?

        At a guess the direct drive hubs are 8″ diameter so the spokes are short & strong.

        note that motor heat should dissipate well in hubs.

        I hear copper moors are cooler than cheaper lighter aluminium.

        I think i have to bone up on controllers. They seem to be – well – in control.

      • Side loads (bicycle wheels upright, not leaning into turns, making a car like turn). I am genuinely curious how that setup would age.

    • Exactly my thoughts. These mountain bike wheels with hub motors are an awesome building block componnt for this kind of stuff & real vehicles too.

      my whim is a 2 wheel drive bike. Thake one mid-drive ebike & add a front wheel hub motor also.

      which begs the question, can kit components be shared ?

      e.g. will one battery/controller/throttle conveniently & cheaply suffice?

      It seems intuitively sensible to use lesser powered motors on the front wheels given traction.

      I like the notion of direct drive hub motors here, geared motors are not built for such tasks. The plastic cogs will strip.

      • I forgot to mention but it also depends on the RPM of the motor. But I reckoned that you might have bought the motors for your family already. So how are things going?

        • I agree re rpm, which is why i have 3 mid drive ebikes, mainly a 350w 24 speed 36v mtb

          having said that, i have no tacho as far as i can tell and no idea what the ideal revs are. My hearing aint much.

          direct hubs seem best for a buggy tho

          however the 2 speed hubs sound way cool too

          with 4 hub motors & 4 throttles, in theory you dont need steering. do it like a tank. power outside wheels.

          • splice the throttle cables for front together and back together…stick them on handlebars and then you have the choice of Rear wheel drive, front wheel drive and All wheel drive…sound way cool I am sooo tempted to build it….except i cant drive it around the streets, police would pull me over just for its looks.

    • many raise the issue of wheel strength for using hub motors on your buggy.

      When in Rome…

      Much of the world relies heavily on cargo trikes and bikes.

      A basic rule is, as the loads go up, wheel sizes go down.

      Compared to cars, 26″ is a lot – a big ask for it on a buggy. Good for about 70kg (most mtbS are rated for ~140kg) per wheel methinks.

      The next common (24″ isnt) size is 22″ i think. lot stronger and lower gearing, good for a buggy.

      maybe just respoke the hubs into some junk kids MTB wheels.

      One way would be weld 2 x kids mountain bikes together, spaced like a catamarans hulls, and have a tiller joining the steering heads.

      KISS = 2 WD (2 hub motors, maybe 2 speed ones), 2 controllers, 2 throttles, 1 battery.

      a common approach in the 3rd world is to attach a 2 wheeled barrow to the front of a bike, swapping out the front wheel fork assembly. so you have 2 passengers in front & maybe one behind standing on pegs. They get out and push at times.

  13. People are missing the point here , more important than the Hub Watts is the Voltage
    I mean a 350w hub 24v is slower than 250w hub 36v , you actually can make a 250w hub go faster than a 1000w 48v hub by increasing the Voltage to 60v on a 250w hub
    however the 1000w hub will always have much more torque’ , I ve built electric bikes its a hobby

    • hey iv got a 48v 250w scooter can u tell me how to get more speed out of it plz

      • get off! lmao no. find a larger gear for the motor and a smaller one for the wheel. you could also increase voltage BUT first check the capacitors (look like battteries…sort of are) on your circuit board and make sure you do NOT GO PAST THE VOLTAGE written on the side of them; otherwise…Its dead. you could also upgraade the circuit to a higher wattage model then add extra volts.

        Also, try converting it to lithium batteries if the scooter uses lead acid…it will be better.

        • i got myself some kids 100w 24v electric scooters (2 of them) for spares/repair on ebay and i have been modifying one of them to be crazy at speed…converted it to 48v (used all batteries from both of them on one) modified the circuit board shunt for more amps…and now it is too quick to go around the corner! hehhehehe I love modifying! it did make the motor HOOOT! like a clothes iron’s surface and now the motor makes a funny noise sometimes when hot…i think the windings are too thin for th epower inside the motor; but it is sooo fun.

  14. Yes, increasing the voltage increases the no-load speed. But winding and gearing are typically arranged so the no-load speed at the rated voltage is 25KPH +10% So a hub sold as a 24V hub is typically just as fast as one sold as a 36V hub. And also depending on the rim fitted, obviously!

    As others have said, the various laws in various countries, (usually 250w or 750w) don’t come with standards for how that power is measured. They’re not even very precise about how the max speed (15mph, 25kph, 20mph) is measured.

    IMHO, 20mph, 500w feels about right for an unlicensed, unregistered, untrained, uncontrolled vehicle on today’s roads and cycle paths. And in many cases an actual speed of 10-15 is more appropriate. For instance, I really don’t want to see people doing 20mph on the towpaths around London when it’s mixed in with pedestrians.

    • towpaths…london…pedestrians….im cranking up the power!!!………..Im only joking i would stick it down to 200w mode or maybe even pedal with assist off….that is what i tend to do…just pedal it unitl past the masses then….power it up! heheh

      • Seriously – we have to show restraint or we’ll all get banned. That said – I love to fly down the road or trail when its empty. I rode last night after dark on my ebike. Rode for several happy miles on new tires last night after 10PM. Just rolling along at 15-20 mph.

  15. can i get a 500 watt motor in india?

    • Mail order just like the rest of us. You’re closer to China so I would assume it would be easier to get in India than for us here in the USA. Do you have access to eBay in India?

  16. But how about the MXUS 250W?

  17. i used a 250W assisted motorbike that literally made me feel like flying up the hills also in forest terrain. Definitely enough for anyone unless you really want a motorbike instead. I like motorbikes too but that is another matter entirely. The only thing i could wish for more on my bicycle is a larger battery so i can go for longer offroad. A 100km ride in the forest drained the battery so I had to pedal manually the last few kms.

    • that must be about 60 miles range! damn…i get like 20 miles range and i was happy with that form a 48v 20ah vpower lithium 13s pack.

    • Most likely… you didn’t use a 250W assisted motorbike, it just said it was 250W.

      The thing is, you don’t know how much power the engine was putting out, 250W is just “maximum continous power” to be EU legal, but it could actually be doing 200, 250, 500, 750W… god knows. The law says that maximum continous power has to be 250W, which is the rated power the engine is supposed to be able to take indefinitely, but doesn’t limit maximum peak power. So you have really no idea of the power of the bike you used.

      Also it matters what sort of motor; mid drive 250W is going to climb hills like a mountain goat, especially when 250W is a big fat lie to fool the regulators, while a genuinely 250W direct drive hub motor (which has it’s advantages, reliability, easier on transmission parts, etc) is going to be really, really bad outside of mostly flat ground. From what I hear, Yamaha mid-range 250W motor outputs actually 400W peak, for instance – and this IS entirely legal, while top of the line Bosch 250W engine outputs 850W maximum, which is also entirely legal (in the EU).

      This doesn’t mean one is more powerful than the other because there is no set standard for measuring peak power of an e-bike, though (input amps x volts, or output on a dynamo, going to be entirely different) and you have no idea how they measured.

      So, setting actual maximum output to some 750W, but setting some real standard how that power is measured, wouldn’t actually change much at all (indeed the 250W bike you rode might fall over the limit), just make the whole regulatory scheme clearer, and give you a way to actually compare engines without, you know, rigging them up to instruments to see how powerful they actually are.

      I’m looking now at an ebike which says “smart hub motor 200-400W”. This is not technically road legal, although manufacturer showed me they have EN 19154 certificate. The exact same engine can be bought online, which says “smart hub motor 250W”, which mentions in small print that it can go from 200-400W, but 250W is nominal power. This is road legal. It outputs less power than top of the line and entirely 100% legal Bosch and Yamaha mid mount drives.

  18. I build ebikes, I use nothing less than 1000 watt motors, I use heavy steel tri link frames, and for range the biggest 48 volt packs i can fit, currently thats 4×12 volt 12 amp hour sla batteries, which weigh 16 kilos, its a massive weight to put on a bike, some have even requested the larger 6 kilo 17 amp hour batteries, the bikes weigh in total around 65 kilograms, they are big and heavy for a reason, to get at least 10 miles at 25-30mph, in all weathers, up and down hills, to take crosswinds, headwinds and to take on the crap b roads full of pottholes, and the main reason I build these bikes ?, safety, its much safer for you to ride along with traffic, than be a hindrance to it, at 25-30 mph the bikes are safer than a piddly assisted 250 watt motor that is hard pushed to even get you to 15mph, at 1000 watts you have enough power to pull you up most hills without peddling, with a full long range battery on board, my bikes can also carry an additional 20kg of cargo and still maintain the pulling power and speed, it is silly to limit the motors to 250 watt, sure, 15 mph is the limit, but on a fully loaded bike a 250 wouldn’t even pull you to 10mph, I now fit a limiter to my bikes, and show people how to switch them off, 20- 25mph is so much safer for them on the roads we have here…

    • try 48v lithium packs….HUUUUUGGGE Difference, I live on a slight hill and it flies to over 20mph up it from a stand still half way up

      • whereas sla is heavy laggy and slow, although do last quite a few cycles.

        • top speed i got is about 37MPH on flat but i was bouncing it up and down to get that lol.

        • The lithium batteries last longer than SLA batteries don’t they – longer meaning more charge/discharge cycles.

  19. 250W = not enough, I’m over taken by push bikes! It be hardly enough to lift its own & battery’s weight up hills.

  20. 250w Vs 1000w on 48v
    For speed and at least 100kg carrying
    1000w is strong enough?
    I want 30km/h not as full speed!
    Any help?

  21. can somebody help me ….our team is making a solar car for the first time… we are using 1500watt hub motor 48v with torque 35N-m and the weight of the car including the driver is 250kg.. so is it possible to run the car??

    • 48v is brilliant on a bike… but for a full size car…i would go with no less than 96v maybe 72v to get the car running nice and smooth off the line etc. 48v you would feel sooo much lag in a full size car due to weight and size; also it would be best to have a hub motor in at least two wheels like both fron or both back; or maybe all four hehe. it would get a lot more expensive but at least the end result will be USABLE on a DAILY basis.

      • I don’t think he means a car in the automotive sense. I think he means a four wheel vehicle made of bicycle parts with a large solar panel on top to help keep the batteries charged. I would test it with the 1500 hub motor and see if you are happy with the performance. Then if you aren’t (and assuming competition rules allow it) switch to a mid-drive so you can make use of bicycle gears and keep the motor at whatever rpm it runs most efficiently at which I would guess is also the speed where the temps are the lowest.

  22. I am disabled and weigh 255 lbs and need a kit for my Schwinn Trike. What size motor do I need to do low speed (5-10 mph) not pedaling and some moderate paved hills (on streets) some pedaling. I need something to get longer distances without hurting myself.

    • on the schwinns i have seen many use the 1000w system..just buy the ones with an lcd display; these ones have a wattage limiter that you can select to keep it as slow or as fast as you want….mine have 5 speed settings. 200w, 400w, 600w, 800w,1000w 🙂

  23. how shall i get hub motor in india

  24. cooling comes up a lot here.

    i have two similar mid drives, but only similar.

    One (usual bolt on to frame and 7 gears from 1 front sprocket, not sure of brand, but works fine) is definitely a problem on a hot day longish incline. I schemed of transferring and dissipating heat from the motor housing to the frame with metal straps.

    fate intervened and the second one was purchased. its doable but a drag to have to fiddle with.

    the second one is cool as. The motor is integrated with the frame (i linked to it in another post) and heat just seems to disappear. Given the above 250w overheats, it bodes ill for souping it up a bit. The second one is even 350 watts. 500w would be no problem.

    so yes, it’s an issue

    I haven’t done hub motors yet, but seems to me, some smears of thermal heat paste like they use for CPU heatsinks, where the spokes contact the hub and rim, cant hurt heat dissipation.

  25. I ride 11 miles into work and 11 miles home every day (even in the rain). My route is mainly cycle track with some muddy paths thrown in. I find the 250w motor fine, I managed to hack the speed restriction by telling the cycle computer I had a 16 inch wheel instead of 29…

    But honestly more than 18 miles per hour I feel isnt safe on a bicycle without extra protection. I wear a helmet and gloves of course but as I said my 250w motor easily gets me to 18mph and that feels totally comfortable. Yes on hills I do need to peddle a fair bit, but the motor helps out and I find even on long gradients that’s certainly manageable.

    Obviously everyone is different, not everyone will want to be giving the bike a good peddle. I personally enjoy it as it gives me that extra bit of exercise without knackering me out.

    I think we’re in a great position these days, these motors are great, the only thing I want to see happen soon is the battery price coming down. I get about 40 – 50 mile range on my bike, but the battery costs around £600 for the samsung cells. After 2 years I need to replace them, which is a shame because I bet the motor wont need replacing for a good while!

    • u dont say volts or if u charge at work, but an equivalent or better, but a bit heavier & uglier lifepo4 battery pack would serve you much better. very little sag as the trip progresses, and they ~never wear out if u r nice to them.

      Ping are perhaps the nicest (long story), but expensive.

      u need a battery that gives u at least a constant 250W (if it really is 250w – they often understate) for an hour it seems u r ok for 18 miles. so an 8-10ah 36v battery should be sufficient w/o being too heavy.

      w/ a mid drive – pedaling is entirely optional.

      I agree re comfort and safety at 20mph+ – its not a nice feeling any more.

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