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[BrianTRice@gmail.com]

When we talk about physics, it costs a certain amount of energy to keep the bike rolling at a certain speed. The power is only needed to withstand the resistance. That's independent from the rpms of the engine. So theoretically, the energy use should be equal.

If your bike went 100 mph at 100%throttlr with the gearing and you make it go 60mph at that same 100% throttle by only changing the gearing.   You think the bike that tops out at 60 is going to be more efficient than the bike that tops out at 100??? If they are both traveling a constant 55mph? Furthermore you think the motor/bike going with top speed of 60 is going 55mph is going to draw the same amount of power as the 100mph bike going at  55% of its throttle....

For what it's worth, you have provided no arguments for your incredulity. You could save all of us some time by just working out the logic or pointing us to a repeatable explanation.

Let's say that his premise is right: that the dominant factor in efficiency is overcoming resistance. The part of the argument that appears to have a reason for debate is that the motor and belt, when operating at a higher RPM, provide lower efficiency for the same speed because of internal losses (by some percentage which would be worth an estimate or calculation).

That's an argument I can buy, that took less space than your commentary. Let's try that next time!

[Cortezdtv]

Yikes....





Electric motors use more power at 100% throttle than they do at 50% throttle....


At 35 mph a fx can go 80 plus miles
At 60 it can barely go 30.....  Does wind resistance equal all 10 of those miles? No some of it is the motor using more power at the higher speed....

[BrianTRice@gmail.com]

Yikes....

Electric motors use more power at 100% throttle than they do at 50% throttle....

At 35 mph a fx can go 80 plus miles
At 60 it can barely go 30.....  Does wind resistance equal all 10 of those miles? No some of it is the motor using more power at the higher speed....

That argument does not prove what you assert it does; you're relating power output to the throttle setting, which is accurate but the throttle is not a direct relation to speed or drag.

We're asserting that the dominant factor in the throttle setting at steady-state on level ground is the speed, because of rolling resistance. This appears to be uncontested. I think my argument about the RPMs adding some amount of internal losses is a factor that supports your implied assertion, but that doesn't make your argument believable.

Try to be less upset when people don't engage with you when you talk that way. You're insulting us.

[Lecram]

Yikes....





Electric motors use more power at 100% throttle than they do at 50% throttle....


At 35 mph a fx can go 80 plus miles
At 60 it can barely go 30.....  Does wind resistance equal all 10 of those miles? No some of it is the motor using more power at the higher speed....

Again: an electric bike doesn't have a throttle...

You are assuming that you have to turn the accelerator more when there is a smaller gear at the engine. And that's not necessarily true. You'd do better to at least try to understand what I am saying (even though I am not native english).
The motor is using more power at higher speeds due to the resistances

[Lecram]

When we talk about physics, it costs a certain amount of energy to keep the bike rolling at a certain speed. The power is only needed to withstand the resistance. That's independent from the rpms of the engine. So theoretically, the energy use should be equal.

If your bike went 100 mph at 100%throttlr with the gearing and you make it go 60mph at that same 100% throttle by only changing the gearing.   You think the bike that tops out at 60 is going to be more efficient than the bike that tops out at 100??? If they are both traveling a constant 55mph? Furthermore you think the motor/bike going with top speed of 60 is going 55mph is going to draw the same amount of power as the 100mph bike going at  55% of its throttle....

The part of the argument that appears to have a reason for debate is that the motor and belt, when operating at a higher RPM, provide lower efficiency for the same speed because of internal losses (by some percentage which would be worth an estimate or calculation).

That's an argument I can buy, that took less space than your commentary. Let's try that next time!

I agree with that. The question is: do these few more revs really influence the range? Or is that so few that it is barely measurable?

[Cortezdtv]

yes if you drag the bike out to its maximum range YES IT IS GOING TO MATTER, your physically going to travel a distance that is much less than the other gears.... if you have the smaller gear in the front and stock in the back



how can you say an electic motorcycle doesnt have a throttle....? yes it does... and its a direct representation of how fast your are going. The gearing can increase or decrease this but the throttle serves the exact same function as in a gas motorcycle only difference is this would be a "fly by wire" style throttle where it goes into a computer like most modern cars have.....

[Cortezdtv]

the true problem is everyone has a different view of efficency...
are you trying to.....

go maximum distance in shortest time
go maximum distance using least power
go maximum distance using least power and shortest time

some are looking at it as which is the most efficent to go the maximum distance the fastest (tallest gearing (25/98))

if you were looking the maximum distance and didnt care about time, well shit run no sprocket and push the fucker....


which would be the same as I beleive what your getting at lecram, maximum efficency to you is .... most efficent acceleration, you dont care about top speed so the time would go out the door as well. so you want to know if the 25 in the front 132 rear is going to be more efficent accelerating than the 28/ 132

if you really want to know i can set 2 bikes up on a stand one with a 25 and one with a 28 tooth fronts
or maybe a 30 front to give us all more accurate and bigger spread in the results

 I could set both bikes up fully charged accelerate at max throttle so many seconds see which bike used most power, then do same thing riding them so you can get results loaded and unloaded..... that would prove the efficency...


they arnt all the same question, sorry for my arguementative ways....


i look at efficeny as total distance covered least amount of time and power... so to me 25/98 will always be most efficent as proven by terry.....

[Doug S]

Cortez....again....nobody's arguing that with shorter gearing, it's going to take more motor revolutions to travel a given distance. BUT with the shorter gearing, the motor has to exert less force (torque) while it's doing so, which means it can use less fuel per revolution. It's even possible that the motor might operate more efficiently at the higher rpm, which is actually fairly common among ICE engines. That would mean that even though the motor has to turn MORE rpms to travel the same distance, it still might do it using LESS fuel.

My point all along has been that the electric motors used in our bikes are very efficient in almost every corner of their operating envelope, which means they can very efficiently give you power at almost any rpm. If your bike is using 5 horsepower to stir the air (aerodynamic drag) at a given speed, it almost doesn't matter what rpm the motor is turning to give you that power. There's no guarantee you'll get more miles per kWh with higher gearing than you'd get with lower gearing.

[Cortezdtv]

maybe terry will chime in on that very last sentence... Ive messaged him, ive read something somewhere where he responded to that exact question, I know results riding my fx's but it might be totally different on the 250lbs heavier s platforms. The 250lbs might make the efficency change.

[Lecram]

yes if you drag the bike out to its maximum range YES IT IS GOING TO MATTER, your physically going to travel a distance that is much less than the other gears.... if you have the smaller gear in the front and stock in the back



how can you say an electic motorcycle doesnt have a throttle....? yes it does... and its a direct representation of how fast your are going. The gearing can increase or decrease this but the throttle serves the exact same function as in a gas motorcycle only difference is this would be a "fly by wire" style throttle where it goes into a computer like most modern cars have.....

This is a throttle:


I have never seen this on an electric bike. You probably meant an accelerator. Well, that is no more than a potentiometer that tells the Sevcon how much power the engine may use. It seems that you won't understand that a 10% lower ratio means a 10% higher need of energy. The need of power is the same. And the power determines the energy consumption.
I am done with this discussion.

[Cortezdtv]

Here directly from the zero service website....

I'll get a color picture off my bikes if you need, they have the same "throttle" on the original Electricross's if you want a electric motorcycle history lesson I'll show you one on the Electricross and all the years leading up to a 13 if you would like....



Now you can get offended....

[KrazyEd]

   Sorry to rejoin the fray at such a late date. Most of the arguments are valid given the person's goal. If I want to go to Cross Country, or, to Bonneville, I don't care what the Zero to 60 time is.
If I am only going stoplight to stoplight, I don't care if the bike can go 200 miles per hour. The efficiency question also has to take into account the riding being done. If going across a flat,
straight, endless, breeze free  section of road at 35 mph, then, the taller the gearing the better ( to a point ). I never have to adjust the throttle ( sorry ) position to compensate, so, will continue
at constant drain until dead. If a rather equal amount of up and downhill are factored in, then, the the shorter gearing may be more efficient as it will add more regen rpms per mile than the
taller gearing. As speed increases, wind resistance becomes more of a factor. Not wanting to get into all of the calculations required, I did a quick search and found a link for someone who did
HP figures for a Chevrolet Cruze ECO horsepower needed to maintain 55, 65, and, 75 mph.  55 = 10.5 hp, 65 = 13.2 hp, and, 75 = 16.4 hp. Difficult to make direct comparisons as there are
such a wide range of variables. That being said, it looks like about 60% more power needed at 75 mph than 55 mph. Even greater difference if you went 35 to 85. This seems to follow what
Zero publishes for range. One of the first things that i usually do to my vehicles is to go to taller gearing as this has historically worked best for MY needs. My FX was no different. I went to a
30 tooth front as I wanted a 100 mph top speed, and, i wanted to shoot for a 100 mile range. Not at the same time of course. As I mentioned earlier in this thread, that was too tall for my
wishes, so, switched almost immediately to a 28. This gives me MOST of the fun of the 25 with a top speed not far off from 100, and, I have had several charges where I have achieved over
90 miles of range. Again, not at the same time. The RANGE RUNS are at uncomfortably low speeds.
   Testing that I did with an Electric Toyota Paseo also showed that lower rpm ( taller gearing ) produced greater range. Most people at the time were saying to pick a gear, leave it there
all day and go. The person that I bought the car from said that he used 3rd. I did this, and, was always concerned that I might not make my 20 mile commute. I started using all 5 gears.
Initially taking each gear up to as high an RPM as was safe before going to the next gear, not fast, just held each gear as long as needed. This produced a low amp draw, and, greater range.
I noticed that if I happened to leave it in a taller gear rather than shift down ( no regen ), that my amps went up, but, my voltage use went down. So, I tried short shifting. Used all 5 gears,
but, shifted out of each gear as early as possible. Again, amps were higher, but, voltage use was lessened, and, again, my range increased. I ended up getting close to 50 mile range with this
driving style. The Toyota had a DC motor, so, not sure how applicable this would be to compare to the AC motors in the Zero.
   I generally do the math to see what SHOULD happen before I make a change, then, make one change at a time and verify results. Unfortunately, I did not do any real RANGE RUNS with
the 25 tooth on the FX before I switched. I do know that the range is greater with the 28 under similar riding, but, can not attest to the exact amount.
The BEST option is to have a Vehicle for each desired task. One for top speed, One for Range, One for passenger, etc.. Since this is not really an option for most of us, then, we have to go
with what meets our needs to the greatest extent. If I were to start over, I would probably keep the 25 front for everyday riding ( MAX FUN ), and, swap to the 98 tooth rear for max range.
This would be ( FOR ME ) the easiest way to have TWO bikes. Less time to swap wheel / gear / belt than to swap motor sprocket.
   Sorry if I rambled. If anyone has any questions or comments, feel free to PM or email.

[Patrick Truchon]

I thought I'd add my 2 cents in the form of an experiment: I used my drill to lift a bucket using a piece of string.  One set used the drill as is, the other set doubled the radius ("gear").  I won't spoil the results, but it should help figure it out whether or not a different gearing option changes the range...

[Kocho]

Did you also change the RPM on your drill to lift the thing in exactly the same amount of time? Or did the "taller" gearing lift it quicker? Did you measure the time it took to reach the target RPM from 0? Some food for thought, so you can properly interpret the results of your experiment. Hint: the impact of varying acceleration is huge, and changing a gear without changing the RPM means you are asking the drill to "accelerate" much faster which means it will draw much more current.

The above logic applies to the Paseo gear shifting too. If starting from dead stop in 5th gear you need to make sure you are using the same amps as you would in 1st gear. This means, you would have slower acceleration and higher top speed for the same RPM!

Also, the Ah one can get out of the same battery is quite different, depending on the current drawn. At high currents, you get fewer Ah out of a "fully" charged battery before it "fully" discharges. In other words, the effective capacity of the battery is smaller at higher current draws. So, taller gearing, if used to accelerate at the same rate as lower gearing, will be drawing more current, and even though it performs the same work, it will give lower mileage range ;-)

I thought I'd add my 2 cents in the form of an experiment: I used my drill to lift a bucket using a piece of string.  One set used the drill as is, the other set doubled the radius ("gear").  I won't spoil the results, but it should help figure it out whether or not a different gearing option changes the range...

[Patrick Truchon]

Did you also change the RPM on your drill to lift the thing in exactly the same amount of time? Or did the "taller" gearing lift it quicker? Did you measure the time it took to reach the target RPM from 0? Some food for thought, so you can properly interpret the results of your experiment. Hint: the impact of varying acceleration is huge, and changing a gear without changing the RPM means you are asking the drill to "accelerate" much faster which means it will draw much more current.

If you click on the the experiment link you'll find more details, including the original videos that I made to record the data.  But long story short:

I lifted the bucket a bunch of times at different speeds (using only the "trigger" control, I didn't change the fast/slow setting).  I did that by wrapping the string around 2-cm wheel and again around a 4-cm wheel (doubling the "gear" size).  Each time, I tried my best to keep the speed constant.   After, I used the video time signature to measure how long each lift took, and estimated the "average" current drawn during the lift from the multimeter readings.

You'll find that the data is pretty clean considering how half-assed my setup was.  Of course there's some noise in the data, but the trend is clear I think.  To be honest, I wasn't expecting to get results that clear.  I just wanted to see if I'd be able to see a trend...