What is the optimum build for a long range light motorbike/ebike?

A

azad

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Hi,

I would like to build a long range electric bike or motorbike (400km+ speed as fast as possible). Probably something on the lines of Onyxbike or super73 however, I am having trouble finding the right frame and parts for this. It would be nice if somebody suggested the best parts (motor+frame+battery) available easily to accomplish this. Needless to say, it should be economical and should be worth building than buying a new one.

https://cdn.shopify.com/s/files/1/0147/3118/2180/products/ONYX_RCR_3QTR_Silver_sm_1920x.jpg?v=1591992737
https://cdn.shopify.com/s/files/1/0009/5895/5573/files/Super73_RX_3qtrFrnt_Gray_1024x1024_88e85dba-410d-4a2e-a401-9a69b94c389c_540x.jpg?v=1580486809

If say one would want to improve the onyx motorbike or cake e-cross, how much more range can be achieved if speed is sacrificed?
 
I thought I posted in the motorbike forum!

That is why I was interested in these kind of frames. I already carry 11kg of battery on a "normal" bike so, I am up for a challenge.

Maybe 10kwh with 3kwh/5kwh motor might be sufficient?
 
azad said:
Maybe 10kwh with 3kwh/5kwh motor might be sufficient?
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Ok, that's only 40kg of high performance 18650 cells (not counting physical packaging). But it won't get you 400+ km of range unless you go very slowly. You need to be below 25 Wh/km, and you'll be burning at least three times that much to hold a steady 60 km/h.

I think you can have either the speed you want, or the range you want. If you try for both, you're going to spend a fortune on a bike that's not good to ride.
 
Balmorhea said:
You need to be below 25 Wh/km, and you'll be burning at least three times that much to hold a steady 60 km/h.
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Wouldn't I travel faster as well when I burn quicker the battery?

Let's say if a 10Kwh battery is burnt 25Wh/km to achieve 400kms at 30km/h, wouldn't it be possible to burn at 50Wh/km at 60km/h? (i.e. If the battery cells do provide high discharge rate).

If it is the matter of discharge rate of 18650 cells, how about using other type of batteries?
 
azad said:
Balmorhea said:
You need to be below 25 Wh/km, and you'll be burning at least three times that much to hold a steady 60 km/h.
Click to expand...

Wouldn't I travel faster as well when I burn quicker the battery?

Let's say if a 10Kwh battery is burnt 25Wh/km to achieve 400kms at 30km/h, wouldn't it be possible to burn at 50Wh/km at 60km/h? (i.e. If the battery cells do provide high discharge rate).

If it is the matter of discharge rate of 18650 cells, how about using other type of batteries?
Click to expand...

I think you're confusing energy per speed and energy per distance. It takes more energy for unit distance to go faster due to the poor aerodynamics that you will get on any motorcycle unless it is completely covered in a fairing or shell. 25Wh/km is the energy usage per kilometer at low speed - at 30km/h with that battery you'd go 400km. At 60km/h and 50Wh/km, you only have 200km or range. Same bike, same battery, but the higher speed will always burn through more energy to travel the same distance.
 
SRFirefox said:
azad said:
Balmorhea said:
You need to be below 25 Wh/km, and you'll be burning at least three times that much to hold a steady 60 km/h.
Click to expand...

Wouldn't I travel faster as well when I burn quicker the battery?

Let's say if a 10Kwh battery is burnt 25Wh/km to achieve 400kms at 30km/h, wouldn't it be possible to burn at 50Wh/km at 60km/h? (i.e. If the battery cells do provide high discharge rate).

If it is the matter of discharge rate of 18650 cells, how about using other type of batteries?
Click to expand...

I think you're confusing energy per speed and energy per distance. It takes more energy for unit distance to go faster due to the poor aerodynamics that you will get on any motorcycle unless it is completely covered in a fairing or shell. 25Wh/km is the energy usage per kilometer at low speed - at 30km/h with that battery you'd go 400km. At 60km/h and 50Wh/km, you only have 200km or range. Same bike, same battery, but the higher speed will always burn through more energy to travel the same distance.
Click to expand...

I am not quite convinced that air drag can affect the distance so much considering everything else remained the same. However, I do believe it ought to be the motor resistance. If motor is less efficient at higher speed then sure, it would take more energy at higher speeds but if motor has linear or near linear current consumption then there shouldn't be any problem. Typically, motor is most efficient when it is around 80% of its peak current consumption (or speed). In this way if a motor of say 120% of the desired speed is installed and is used max at 80% of its capacity then perhaps it could be an optimal arrangement?

motorcurve.gif
 
I am not quite convinced that air drag can affect the distance so much considering everything else remained the same.
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In a near-vacuum, this would be quite true. On Earth, though, near sea level, air resistance is the main factor in power consumption, once you get above, say, 25MPH. Air drag matters so much that an EV will get better range on higher altitude roads than on lower ones.
 
azad said:
I am not quite convinced that air drag can affect the distance so much considering everything else remained the same.
Click to expand...

Believe it. If you don't believe me, ask around with some of the folks with higher speed bikes how many Wh it takes to go a kilometer at different speeds. Air resistance above a shockingly low speed - the rule of thumb appears to be 25mph/40kph - becomes the dominating system loss.

If you don't believe us, look here - https://en.wikipedia.org/wiki/Drag_equation. Since everything else in the equation stays the same with the same bike, you will see that drag force is not just linearly related to velocity, but related to velocity squared. At which point doubling your speed increases the drag force by a factor of four. As you are traveling twice as fast, this at best means you double your energy requirements to travel the same distance. This is also why there are no conventional road-going cars that can break 300 mph.
 
azad said:
I am not quite convinced that air drag can affect the distance so much considering everything else remained the same.
Click to expand...
There's a lot of documentation out there showing that it most certainly does; the faster you go the more of it there is, and beyond around 20-25mph-ish, it starts to get serious. You can prove it yourself using a wattmeter with speedometer, etc., that then keeps track of wh/mile, like the Cycle Analyst.

One site that you can learn how entire systems work, including air resistance at speed, different motors, controllers, batteries, etc., is the https://ebikes.ca/tools/simulator.html . You need to first read the entire page, then setup a system (doesnt' matter what) that's capable of the speeds you're after, and then try it at different speeds and see what the wh/mile usage will be.

Then you can try different slopes too, and see how much power is used doing that, so you can also plan about your terrain, as well as the winds and power used by the speed you're going.
 
amberwolf said:
azad said:
I am not quite convinced that air drag can affect the distance so much considering everything else remained the same.
Click to expand...
There's a lot of documentation out there showing that it most certainly does; the faster you go the more of it there is, and beyond around 20-25mph-ish, it starts to get serious. You can prove it yourself using a wattmeter with speedometer, etc., that then keeps track of wh/mile, like the Cycle Analyst.

One site that you can learn how entire systems work, including air resistance at speed, different motors, controllers, batteries, etc., is the http://ebikes.ca/simulator . You need to first read the entire page, then setup a system (doesnt' matter what) that's capable of the speeds you're after, and then try it at different speeds and see what the wh/mile usage will be.

Then you can try different slopes too, and see how much power is used doing that, so you can also plan about your terrain, as well as the winds and power used by the speed you're going.
Click to expand...

So essentially what you guys are suggesting is that it is impossible to build a *Motorcycle* with the current state of the technology?

A light motorcycle can have a weight upto 100kg. Ofcourse I would like to have it as light as possible but if it isn't too light it would be OK as long as it gives me long range with decent speed for highways.
 
maybe consider building a streamlined bike:
https://cybermotorcycle.com/gallery/monotrace/Monotrace-France.htm
 
peters said:
maybe consider building a streamlined bike:
https://cybermotorcycle.com/gallery/monotrace/Monotrace-France.htm
Click to expand...

sure, if the parts can easily be available or can be manufactured single-handedly!

Infact, my original question was about parts (i.e. frame + motor + battery)
 
azad said:
A light motorcycle can have a weight upto 100kg.
Click to expand...

Thing is, you're talking about a battery pack that weighs that much by itself.
 
mistercrash said:
Then the answer is no. Sorry but the parts are not readily available for a 400+ km range bike at 60+ km/h.
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OK, So what is the max that can be attained as a long range light motorcycle? (re-edited the question)
 
Balmorhea said:
azad said:
A light motorcycle can have a weight upto 100kg.
Click to expand...

Thing is, you're talking about a battery pack that weighs that much by itself.
Click to expand...

A 10kwh battery should weight no more than 75kg including the mounting. In this way total weight can be kept 80-90kg for the entire bike.
 
azad said:
Balmorhea said:
azad said:
A light motorcycle can have a weight upto 100kg.
Click to expand...

Thing is, you're talking about a battery pack that weighs that much by itself.
Click to expand...

A 10kwh battery should weight no more than 75kg including the mounting. In this way total weight can be kept 80-90kg for the entire bike.
Click to expand...

You will need 20kWh to do what you describe.
 
azad said:
So essentially what you guys are suggesting is that it is impossible to build a *Motorcycle* with the current state of the technology?
Click to expand...
There are plenty of electric motorcycles already out there, both commercial and custom-built by/for their riders.

Lots of build threads on this forum you can read, right here in this subforum.

I think maybe you're not reading what people are posting, or you're drawing conclusions from insufficient information from not following the suggestions and links, and learning what we're trying to explain to you.
 
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