What is your E-Bike Power to Weight Ratio - hp/lb?

What is your E-Bike Power to Weight Ratio in HP/lb?

  • 0 - 0.0099

    Votes: 1 3.0%
  • 0.01 - 0.019

    Votes: 1 3.0%
  • 0.02 - 0.029

    Votes: 5 15.2%
  • 0.03 - 0.039

    Votes: 3 9.1%
  • 0.04 - 0.049

    Votes: 1 3.0%
  • 0.05 - 0.059

    Votes: 4 12.1%
  • 0.06 - 0.069

    Votes: 4 12.1%
  • 0.07 - 0.079

    Votes: 0 0.0%
  • 0.08 - 0.089

    Votes: 0 0.0%
  • 0.09 - 0.099

    Votes: 2 6.1%
  • 0.1 - 0.19

    Votes: 4 12.1%
  • 0.2 - 0.29

    Votes: 1 3.0%
  • 0.3 - 0.39

    Votes: 3 9.1%
  • 0.4 - 0.49

    Votes: 2 6.1%
  • 0.5+

    Votes: 2 6.1%

  • Total voters
    33

Cowardlyduck

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Messages
4,094
Location
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Hi All
I think it would be interesting to see what people's Power to Weight ratio's are; particularly since power is not everything when you shave off the weight.

For example; my car is ~1450Kg and has ~105KW, which gives a P/W ratio of 0.0440476729.

I've got a Stealth Fighter. It's 3KW and 34Kg. Giving a P/W ratio of 0.0536715342 which is better than my car, even though it has much much less power. :D
The Stealth Bomber is 4.5KW and 53Kg, which gives 0.0516461933.

You can calculate your P/W ratio here.
http://www.easycalculation.com/physics/fluid-mechanics/power-to-weight-ratio.php
Anyone know how to embed this?

Of course, this will be highly variant with accessories/extra's you add to the bike, adding weight, and your weight. So for this poll just use the weight of the bike as you normally ride it with the power you would normally have available.

Cheers

*EDIT* Seems to be 2 ways to do this; Kw/Kg and Hp/Lb with each yielding different numbers. For this Poll we'll do it in hp/lb so convert it to horsepower and pounds first if calculating it yourself...or just use the site above since it seems to do it for you automatically anyway.

Cheers
 
I have a BMC V2T and going up some of the hills in the area I pull 2100W my bike weighs in at 250LBs with me on it and so P/W ratio is really only 0.0112645856. My motor would have a meltdown in just a few minutes even at this power level but the hills are not that long so not a problem. I used the ebikes.ca simulator to estimate the watts as it seems to be quite accurate for everything else I have tested. If I just used the 2100W the motor will actually do and the weight of just the bike with the calculator it would be near the same as yours 0.0512026616 in the P/W arena although that's just the potential it is not what you actually see/feel.
 
Well, if the ratio is as the formula on that website says:
"Power To Weight Ratio = ( Power / Weight ) "
then using Kilowatts for power and Kilograms for weight, my CrazyBike2 is a ratio of 0.0331:

4.5kW (peak power at startup) / 136kg (including rider) = 0.0331
(not including rider cuts weight in half, so ratio increases to 0.0682).

However, if I use that site's calculator, it gives me
4500 watts / 136 kilogram = 0.0201268253
which is wrong, unless all my calculators are broken, or I don't know how to do simple division. :?


Similarly, for the Stealth Bomber above, that comes out 0.0849, rather than 0.0516


EDIT (added): Oh, and before taking the shunt mod off the controller, it was more than double that power for a 0.0735 ratio, but it blew up the controller in a stall-test trying to get a wheelspin in dirt (back end is just too heavy to lose traction even with 8KW+, at least with the knobby that was on it at the time. :lol:). So I don't count that since it wouldn't have been useful having to repair the controller every few rides. :/


DayGlo Avenger is around 80lbs, and about 1200W, oddly enough also for a 0.0331 ratio. Strange that it comes out the same.... :? With me on it that's more like 0.0115.


The Fusin Test Bike is about 60lbs ATM, and 1000W, for a 0.0368 ratio. With me on it that's more like 0.0105.
 
  • Commuter Pack only (15S6P) @ 4 hp = 0.0377358491
  • With Trailer (15S26P) @ 4 hp = 0.0133333333 (estimated cos I really don’t know the precise weight of this assembly)

I used the Commuter Pack for the survey. Seems quite low. I imagine a high ratio would not travel far before needing recharge.
~KF
 
This is power at the controller right and not power through the wheels?
 
I'm pulling 3000W cont. at max speed. I see double that in peak power. Bike is around 37Kg. Came out @ 0.049.
 
amberwolf said:
Well, if the ratio is as the formula on that website says:
"Power To Weight Ratio = ( Power / Weight ) "
then using Kilowatts for power and Kilograms for weight, my CrazyBike2 is a ratio of 0.0331:

4.5kW (peak power at startup) / 136kg (including rider) = 0.0331
(not including rider cuts weight in half, so ratio increases to 0.0682).

However, if I use that site's calculator, it gives me
4500 watts / 136 kilogram = 0.0201268253
which is wrong, unless all my calculators are broken, or I don't know how to do simple division. :?

Your right...and wrong. That site is still doing (Power / Weight) to figure out the ratio, however it's converting it to horsepower and pounds before it does the calculation.
Found another site that does the same thing so I'm pretty sure it's not calculating it wrong.
http://www.ajdesigner.com/phphorsepower/horsepower_equation_power_to_weight_ratio.php

I actually don't know what the standard is. Seems like both are in use.
http://en.wikipedia.org/wiki/Power-to-weight_ratio

For this poll well use hp/lb. Ill edit the title/poll to reflect.

Sorry for the confusion.

cal3thousand said:
This is power at the controller right and not power through the wheels?
We'll say controller, since there's too many variables to the wheel and not many people have access to a dyno to really test this.

Cheers
 
On my 4t astro3220/hv160, 12s lipo, drivetrain test bike:

I did some throttle tuning a couple of weeks ago and did a full throttle run on sticky pavement. No wheelspin, no clutch slippage, front wheel in the air for 300ft.
According to the castle log, pulled 24kw. The CA showed 478 max amps. My bike weighs 75lbs. 32.18hp/75 lbs = .429

In normal usage though, 8kw is usually the most I see as far as a continuous number. So, 10.7hp/75lbs = .143
 
We've done so many dynos now with most hubmotors and small RC motors output dropping to <60% when you start feeding them serious power. Or with the HX35 where feeding it 8kw, 10kw, 20kw or 40kw all output inside of 1hp of each other.

We know the 2pi made some real power, 18-19hp I think?
Farfels new bike makes real power too, but I won't spoil that.

My bike is >0.5hp/lbs with real measured output at the tire. My GSXR1000 is also very close to that. The bicycle is 10x more thrilling to ride. :)
 
Ok, if i redo it as hp/lb, then using 746W per hp:

CB2: 4500W / 746 = 6.032hp / 300lbs (with rider) = 0.0201
CB2: 4500W / 746 = 6.032hp / 150lbs (without rider) = 0.0402

DGA: 1200W / 746 = 1.608hp / 230lbs (with rider) = 0.0070
DGA: 1200W / 746 = 1.608hp / 80lbs (without rider) = 0.0201

FTB: 1000W / 746 = 1.340hp / 210lbs (with rider) = 0.0064
FTB: 1000W / 746 = 1.340hp / 60lbs (without rider) = 0.0223
 
with me on it will have 0.06 hp/lbs raw no losses to heat included, 175lbs total me and my bike

wonder how that will feel. right now i have about half of that. and next summer ill se if I try 0.08hp/lbs... but might not do that don't know :p
 
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