E bike milage

[Oskaro]

Hey guys hope your all having a good day,

I am completly clueless jn the e bike section sorry for noobie questions. I am going to build an E bike to kill some of the boredom in the lockdown times.

I was thinking of doing 5000w or 3000w hub motor with 72v40ah battery, the total weigh of the bike would be 30kg and me 75kg running on 26inch wheels.

The question is roughly how many km/miles I would do on a full charge without pedalling? Considering that I were riding at 30mph.
Also which hub motor would have resulted in draining the battery faster at same speeds?

Thanks in advance guys.

 

[DogDipstick]

Good luck hitting that target, friend.

I got 5-8Kw peaks and 3-4kw contin... 30mph bike... 15Ah @ 72v... 17lb frame... (light)... small QS motor.... (light). 100A ( peak only) and 83v charged. ...

...and I am at 85 lbs for the bike, 45lbs on the rear axle, 40 lbs on the front axle... Light as I could make it this time around and still handle the power with any range.

Some very careful tradeoffs for reliability vs performance here.

40Ah will be much heavier. Big QS will be much heavier. Trying to build those into an ebike is much heavier.

I got one of the lighter high power hub motor ebikes I have seen without going crazy expensive or craxy powerful. Novice bike, yes, but still enough to hurt yourself good. Put me in the hospital once already, 10Hp.

I get a solid 22 miles riding reasonably fast, on that 15Ah. Average. I can get alot less if I let it cool down between travels, then hit it for harder currents for more time of the charge. Or alot more if I stay under 20A.

Consumption? I use about 50Wh/mile for that 3-4kw. Strict stop and go, pulls, to full speed, the most I have used ( consumption) is about 70Wh/mile.. and tat has some good umph. Best is about 20-22Wh/mi. Pedaling.

There are ways to waste power with the wrong choice, or save power with the right choice, desired speeds, power levels.... I have a 8.5Kv hub motor @ 72v with a 50A contin controller. 24" wheel diameter.


Welcome to the forum.

 

[MadRhino]

The faster you ride, the steeper the power usage curve. Aero drag is the enemy of efficiency. Weight comes next, pretty far next.

We like building light weight because of handling, maneuverability, and performance... not for efficiency. Only two factors can significantly improve efficiency: slower speed, and aerodynamics.

Your target weight can’t be achieved with your choice of motor and battery, that are making 30 kg already. Those big motors are suitable for fast ebikes with motorcycle performance, not for those who target light weight and long range.

 

[MadRhino]

...
The question is roughly how many km/miles I would do on a full charge without pedalling? Considering that I were riding at 30mph.
Also which hub motor would have resulted in draining the battery faster at same speeds?

Motors will give similar results, all other factors being equal.

Maintaining 30 mph does consume about 700 watts riding an upright bike without any adversity (flat ground, hard surface, no wind).
That, is dreamers efficiency. You will have to accelerate from 0 to 30 mph and it does consume much more than maintaining that speed, how much depending on how much weight and how quick you accelerate. Thus, how often you will need to stop and accelerate to 30 mph will make a big difference in range. Then, you will have adversity: hills to climb, wind to fight, and each cornering will eat some power.

How you build your bike, how and where you will be riding it, can make so much difference in range that it is impossible to predict unless you are giving us all the factors that are affecting efficiency. Right now, I can only tell that your 72v 40Ah battery can give you a range between 20 and 100 miles. :wink:
You will need to ride very conservative to do 100, and very aggressive to drain it in 20.

 

[LeftieBiker]

Don't dismiss pedaling as something that "real" E-bikers don't do. Nice and easy but more or less constant pedaling can extend your range by a lot - like 50%. You also don't need all that wattage being sucked by the motor if you just want a nice, brisk ride and the ability to climb hills fast, without breaking a sweat. I can do everything but ride at 30MPH with my 500 watt geared motor, and 22MPH seems plenty fast on a bicycle...

 

[donn]

Don't dismiss pedaling as something that "real" E-bikers don't do. Nice and easy but more or less constant pedaling can extend your range by a lot - like 50%. You also don't need all that wattage being sucked by the motor if you just want a nice, brisk ride and the ability to climb hills fast, without breaking a sweat. I can do everything but ride at 30MPH with my 500 watt geared motor, and 22MPH seems plenty fast on a bicycle...

This is true, but I guess you unintentionally made it sound like you could get 22mph at 50% pedal. By the motor simulator, it looks to me like at 22mph on level ground you're going to have a 422W load, for a pedal input of over 200W, which seems a bit more athletic than "nice and easy." 50% at the conventional 100W pedal input would get you 16mph, which I agree is a pretty reasonable speed.

 

[LeftieBiker]

Don't dismiss pedaling as something that "real" E-bikers don't do. Nice and easy but more or less constant pedaling can extend your range by a lot - like 50%. You also don't need all that wattage being sucked by the motor if you just want a nice, brisk ride and the ability to climb hills fast, without breaking a sweat. I can do everything but ride at 30MPH with my 500 watt geared motor, and 22MPH seems plenty fast on a bicycle...

This is true, but I guess you unintentionally made it sound like you could get 22mph at 50% pedal. By the motor simulator, it looks to me like at 22mph on level ground you're going to have a 422W load, for a pedal input of over 200W, which seems a bit more athletic than "nice and easy." 50% at the conventional 100W pedal input would get you 16mph, which I agree is a pretty reasonable speed.

And that's my typical riding speed when I'm not loafing or tired. I was saying that a 22MPH top speed isn't bad, not that gentle pedaling would get that speed. Even so, I don't have to work really hard to go flat out. In fact, I could use a slightly taller top gear...

 

[Oskaro]

Thanks Im so glad I've came across you guys thats was very informative, by the looks of it I was so mistaken about performance output and consumption for those things.
Looks like I need to get back on earth and stop dreaming

I will try to be more specific this time, I care the most about milage and the ability to climb steep hills as I live in Norway which is famous for its hills. I would also prefer higher torque then higher speeds I will be at least maintaing the speed of 20mph.

Bike will be 40kg and myself 75kg.
The battery is 72v40ah given under these conditions will it be enough to get at least 50miles without pedalling on a single charge? And also will the 3000watt hub motor be enough for what Im asking for?

 

[MadRhino]

A 3000 watt hub might not be your best choice for the purpose. Given your conditions above, I am not sure that any hub motor is your best choice, unless it is mounted as a mid drive.

Steep hills, preferred torque over speed, long range on hilly terrain... normally require gearing.

We need to know more about the terrain, your typical ride. How steep and how long the hills? Will you have many stops uphill?

 

[LeftieBiker]

If you do use a hub motor, it has to be geared. A direct drive hub might be able to brute force its way up a big, steep hill, but it would use a huge amount of power doing it - and good luck if you have to stop halfway up and then start up again. But yes, a mid-drive motor that can use the bike's gearing is the best way to go.

I wonder if anyone has ever combined a geared hub motor AND a mid drive, for maximum hill climbing...?

 

[MadRhino]

... I wonder if anyone has ever combined a geared hub motor AND a mid drive, for maximum hill climbing...?

Many on ES had done it. More often, just mounting a hub as a mid drive, driving the disc side. Much more powerful than BB drives.

 

[john61ct]

Lightning Rod's Big Block, new XL version being tested in Norway

 

[dogman dan]

Your big problem will not be getting up the hills with a huge heavy hub motor. It will be how the heck do you carry 72v 40 ah of battery, without putting so much stress on the frame your bike high speed wobbles at 15 mph.

To carry 48v 30 ah, I built a specialty long tail cargo bike, which at least did not go into the wobbles till 30 mph. Most bikes simply are not built to carry batteries that big.

The good news is, you can carry a lot less battery, and get up those steep hills, with a mid drive bike. The bafang kit I mean. It won't haul ass up those hills, but it will get you 25 mph on the flat easy, and creep up those hills with maximum efficiency. Start out with at most, 48v 20 ah battery. Less, if you want to carry it properly in the frame triangle. Add more batteries later for really long rides.

Or,, to get the performance you really want, buy a motorcycle.

Or, build the fast hub motor bike, but carry more like 72v 10 ah, and just enjoy fun as hell, but shorter rides.

 

[MadRhino]

Yep. Heavy battery is making it complicated to build a good ride. Heavy motors too. When they are not required for performance goals, most of the time there is a better, cheaper solution.

 

[Oskaro]

I am able to fit a controller and a 72v30-40ah triangle battery inside my giant xl rim, its a big battery so I thought thats the way to go.

So is there any way of maintaining 20mphs and doing 60miles around city with medicore hills without much pedaling?

 

[MadRhino]

Oh yes it is possible. We just try to figure out the best way to do it. See ‘Map My Ride’ or ´open cycle map’ website. Map an example of a ride that you would typically do. It will give us all the details required.

 

[Oskaro]

I wanted the bike mostly to be used as a daily commuter to work and maybe once the weather picks up I will ride it delivering food for some extra cash.

Im not sure how to draw my route on this app, but I made a google map screenshot if that helps, thats roughly my commute to work.

 

[MadRhino]

Well, this map doesn’t show much. Open cycle map would give details. But still, we can see that no big mountain is on your route. Nothing that requires a big motor. Even a cheap ebay kit would do. I would consider building with a Leafmotor or similar size, and a 12 mosfet programmable sinewave controller. Build for no more than 30 mph top speed, so 20 will be well within efficiency speed, and you might want to ride a little faster on the best sections of your commute.

This suggestion still has some reserve. Would be good to know the bike model. Also, since it is city ride, if you will have a lot of stops and trafic lights on your way.

 

[Oskaro]

I have 2 bikes in my garage
Giant ATX XL 27.5
Giant Talon L 29
Not sure which one would be a better fit.

In regards to a motor I found a 1500watt Leafmotor but its 48v is that the one we are talking about? Will it take 72v?

 

[MadRhino]

Motor rated voltage is irrelevant. Any DD hub motor will run with your battery with the proper controller. Wheel size though, might be important. Higher voltage does spin faster, and may produce to fast speed for your build. If the motor winding can’t match your wheel size to produce the desired top speed, you can run it in a smaller wheel. This case does require a bike that has disc brake, for you can’t change wheel size with rim brake.

The Leaf motor is 16 lbs and has a good efficiency. Many on ES had built with this motor and satisfied. Those will help you to select the best components. I don’t know this motor much, because I build fast bikes. But, if I had your requirements, It is the one I would be looking for. You could inquire on their website about their choice of KV, to achieve 30 mph at 72v in your size of wheel. I doubt that they have a 72v controller though. I would buy only the motor from them anyway. Then choose a controller elsewhere, maybe at ebike.ca where a variety of good controllers are available. If you, or a local, is good at lacing wheels, best is to choose a good rim and 14 ga spokes locally and buy the motor alone. To get the best of a motor, you need to make your personalized selection of components instead of buying a kit.

 

[goatman]

have you looked at rswannabe build?
https://endless-sphere.com/forums/viewtopic.php?f=6&t=103634&start=50#p1525987

 

[ZeroEm]

I run a 2019 7T leafmotor at 72v, top speed 31 mph with Grinfineon 40A. It has been great for me but now would have went with the 6T in a 26" wheel just under 40 mph.

 

[dogman dan]

I never said the big battery won't fit. I said too much weight on most bike frames makes them handle for shit. They are generally not stiff enough from side to side, unless modified.

Do put as much of the battery as you can in the middle triangle, 72v 10 ah fits, without making a battery that makes you ride bowlegged. You can definitely pack more weight there, without compromising the frame stability.

60 miles at 20 mph should be possible with 2000 watt hours of battery. that's 30 ah of 72v, Stability won't be a big problem at 20 mph. most of my overloaded bikes, have wobbled by 30 mph. That's why I was saying carry less battery. But at 20 mph, you can pack a ton of battery on a trailer if that is what it takes. Then still have a great handling 40 mph bike, with the smaller battery in the middle.

 

[Oskaro]

Thanks guys I will need some time and think how to handle the battery but for now I have other questions.

I decided to go with the 1500w leafmotor but not sure about the T rating.

Which 2 of the bikes will fit this conversion better giant atx or talon? I will have plenty of space to fit the battery in both of the frames.

Just to make sure I will be able to reach higher torque and speeds on 27" wheels rather then 29" correct?

 

[MadRhino]

I would choose the 7t if building with large wheels @ 72v

And, this controller is a good deal:
https://www.ebikes.ca/shop/electric-bicycle-parts/controllers/c7240-gr.html

They have better, more expansive if you are not on tight budget.

Both bikes are with large wheels, 27.5 or 29 are both large wheels. Building fast bikes or extra torque with fast motors, we use 24’’. But, large wheels are comfortable, without suspension especially.