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[chdfarl]

Zero does not limit off the line torque.

Seriously then what is it! That S that I rode didn't feel like it had half of the 68 ft-lbs that is advertised. That's not criticism or skepticism. It would be nice if someone who really knows would explain it. My asses accelerometer is very accurate and it read nowhere near 60. 

[benswing]

 My experience on all 2012-14 zeros is that the acceleration increases noticeably at 30mph.

[chdfarl]

I wouldn't argue that but its 0-30 or even a firm twist after that if the torque was " instant " you wouldn't simply notice it, it would scare the shit out of you. That's not what at least the bikes that I rode ( Brammo Empulse and Zero S ) were like. Though they were quite smooth they had not 60ft-lbs of kick when I cracked the throttle there was lag that you could see 4:40 on the Zero video that's hard twist on the throttle and at 1:20 and 6:10 on the Brammo video. They went but not the way you'd expect. On any other bike with that kind of torque it would be a hard launch the kind that lifts the front wheel but they felt like small ICE bikes to me. Now that's not saying that they suck but it is hard to see where the " instant " torque is. If it was set to be limited, even though I feel that would suck then it would at least explain what felt like a lag. Look at Cortezdtv's video to see what it would look like. Even though his bike is an FX and 100lbs lighter than an S a 400lb bike with that kind of torque would be a handful but it wasn't. The Brammo did accelerate harder and is 60lbs heavier but still felt lacking to me.

[tyskmoped]

You can believe Biff, he knows what he's writing. The torque is not limited in low rpms, it's set to controller maximum from zero. Look at the red graph in the first picture.

What you feel as acceleration is simple said torque x rpm - resistances. The more horsepower the more acceleration, simple. Again red graph

I had the same feeling as you guys when riding first electric bikes but it's new situation. Blue graph is with gearbox, it shows low gear with less torque makes more power in low rpms and better of the line speed. For example 30nm x 6000rpm > 90nm x 500rpm. That's need to be understood..

[Doug S]

You can believe Biff, he knows what he's writing.

I don't believe anybody who "knows what he's talking about" but doesn't cite any sources or even say WHY he believes what he believes. Just one more voice in the wilderness until that time.

What you feel as acceleration is simple said torque x rpm - resistances. The more horsepower the more acceleration, simple.

Uh, no. Torque is the rotational analog of force (twisting instead of pushing in a straight line), and no less of a scientist than Sir Isaac Newton tells us that force equals mass times acceleration. Horsepower does NOT cause acceleration, torque does; it's just that simple. Horsepower is the ability to supply energy at a high rate of speed, which is only necessary when losses are high, as at high speed. Numerically, horsepower is equal to torque (in ft-lbs) times rpm divided by 5250. In the real world, there are always losses (what you call "resistances"), which is why torque and horsepower are a bit lower when measured at the rear wheel than when measured at the engine....but in any vehicle, losses are pretty small. In a drivetrain as simple as ours is, losses are near to being negligible.

In the real world, a vehicle is limited in its acceleration at low speed only by the amount of torque it produces at the rear wheel, and at high speeds by horsepower. The transition speed, the speed at which horsepower becomes the limiting factor instead of torque, depends on a lot of things, but on my SR it seems to be somewhere in the 60-80 mph range. Even at speeds near or somewhat above the transition, the instant power delivery and lack of a need to shift down three times makes our bikes good performers even at freeway speeds.

[Cortezdtv]

You can believe Biff, he knows what he's writing.

I don't believe anybody who "knows what he's talking about" but doesn't cite any sources or even say WHY he believes what he believes. Just one more voice in the wilderness until that time.

What you feel as acceleration is simple said torque x rpm - resistances. The more horsepower the more acceleration, simple.

Uh, no. Torque is the rotational analog of force (twisting instead of pushing in a straight line), and no less of a scientist than Sir Isaac Newton tells us that force equals mass times acceleration. Horsepower does NOT cause acceleration, torque does; it's just that simple. Horsepower is the ability to supply energy at a high rate of speed, which is only necessary when losses are high, as at high speed. Numerically, horsepower is equal to torque (in ft-lbs) times rpm divided by 5250. In the real world, there are always losses (what you call "resistances"), which is why torque and horsepower are a bit lower when measured at the rear wheel than when measured at the engine....but in any vehicle, losses are pretty small. In a drivetrain as simple as ours is, losses are near to being negligible.

In the real world, a vehicle is limited in its acceleration at low speed only by the amount of torque it produces at the rear wheel, and at high speeds by horsepower. The transition speed, the speed at which horsepower becomes the limiting factor instead of torque, depends on a lot of things, but on my SR it seems to be somewhere in the 60-80 mph range. Even at speeds near or somewhat above the transition, the instant power delivery and lack of a need to shift down three times makes our bikes good performers even at freeway speeds.

Well said!

[tyskmoped]

Believe what you like but the same vehicle with more horsepower will accelerate faster. Even if the motor has only 10% of the torque, because at same wheel speed you will have more wheel torque if geared for same top speed.

[teddillard]

Stall torque and it's effect on 0 RPM performance is not a theory, just to be clear.  Given that, you're talking about two different things - acceleration from 0 RPM, and acceleration from well onto the torque/power band to a higher RPM. Seems like it'd be hard to measure, but if it's the case, it would certainly suggest throttle mapping, which it sounds like we've confirmed is what Zero is doing. 

My suspicion is that they're concerned with riders who are unaccustomed to riding without a clutch.  Most experienced riders will use the clutch to feather power off the line, even during hard acceleration on the power band, and in some cases use it for low-speed control of power.  You don't have that kind of option with an electric motor. 

Please stop proliferating this rumour, It is not true.  ...

I'm not "proliferating" anything, and certainly not what you call a rumor.  I think it's fairly clear if you read my comment that I have nothing but a suspicion and suggestions.  I'd certainly like someone with credentials and evidence to get on and put it to rest, and I'm certain there are more than a few who read this who could. 

The only dog I have in this fight is the fact that different types of motors have different stall torque characteristics, period.  Does the Energica motor have lower stall torque than a similar (100kw or so) PMDC motor?  Yes.  Is that why I couldn't wheelie it?  No clue.  I have no idea if it was mapped or not, and I really don't care. 

Believe what you like but the same vehicle with more horsepower will accelerate faster. Even if the motor has only 10% of the torque, because at same wheel speed you will have more wheel torque if geared for same top speed.

As far as horsepower goes, you need to have a really basic understanding.  Horsepower = (Torque x RPMs) / 5252.  End of discussion.  http://danielmiessler.com/study/horsepower/  So explain to me how you can have a vehicle with 10% of the torque and more horsepower.

[tyskmoped]

Believe what you like but the same vehicle with more horsepower will accelerate faster. Even if the motor has only 10% of the torque, because at same wheel speed you will have more wheel torque if geared for same top speed.

As far as horsepower goes, you need to have a really basic understanding.  Horsepower = (Torque x RPMs) / 5252.  End of discussion.  http://danielmiessler.com/study/horsepower/  So explain to me how you can have a vehicle with 10% of the torque and more horsepower.

Nothing simpler than this, if it delivers the 10% torque at the 15x rpm than the other motor.

[teddillard]

Nothing simpler than this, if it delivers the 10% torque at the 15x rpm than the other motor.

So, most AC motors run in, say, the 6000 RPM range.  You know of a motor that runs at 90,000RPM?  If so, I'd love to know about it.   

Nevermind, I probably can't afford it.   

[Biff]

Stall torque and it's effect on 0 RPM performance is not a theory, just to be clear.  Given that, you're talking about two different things - acceleration from 0 RPM, and acceleration from well onto the torque/power band to a higher RPM. Seems like it'd be hard to measure, but if it's the case, it would certainly suggest throttle mapping, which it sounds like we've confirmed is what Zero is doing. 

My suspicion is that they're concerned with riders who are unaccustomed to riding without a clutch.  Most experienced riders will use the clutch to feather power off the line, even during hard acceleration on the power band, and in some cases use it for low-speed control of power.  You don't have that kind of option with an electric motor. 

Please stop proliferating this rumour, It is not true.  Zero does not limit off the line torque.  You can hold the rear brake, go full throttle and measure RMS current into the motor and you will see that it is the maximum that the controller will deliver.
Also feel free to install accurate accelerometers on the motorcycle (or accurate wheel speed sensors) to measure acceleration, you will see that it is constant from 0 to around 40mph (at which point wind starts to cause decreased acceleration, and as speed increases the constant power section of the power curve limits acceleration).

Thanks,
-ryan

How do they regulate the power then?

The fx is "limited" 0 to 30
My other which is much less limited sure seems like it has 2x the power from 0 to 30

you can read my lengthy comment here to find out my theory as to why people think the torque is limited at slow speed.

http://evmc2.wordpress.com/2014/07/07/motor-starting-torque-stall-torque-and-motor-types/

I have instrumented bikes and verified the torque delivery, it is very linear from low speed up past 60mph. And as you said you feel like your FX (I believe it has a size6 controller now) has 2x the power of the stock FX, that is right in-line with my theory that what scares people, or gets the front wheel off the ground easier feels much more powerful than it actually is.  Once you get used to it, I bet your acceleration will feel more tame.

To answer your question "how do they limit power" .  Power is the product of torque and speed (Watts = RPM * Torque * pi/30) where Torque is in Newton Meters.  The motor controller (stock FX) delivers 420 phase amps maximum, since phase amps is directly proportional to torque (ignoring any iron saturation and other minor non-linear effects) that means the motor torque is limited by the motor controller. At 0RPM there is 0hp (because speed is 0) as speed increases power increases proportionally until the the motor controller can no-longer put 420A into the motor (BEMF from the motor approaches the Votlage of the battery).

-ryan

[Biff]

Zero does not limit off the line torque.

Seriously then what is it! That S that I rode didn't feel like it had half of the 68 ft-lbs that is advertised. That's not criticism or skepticism. It would be nice if someone who really knows would explain it. My asses accelerometer is very accurate and it read nowhere near 60.

This brings up a good point, and I allude to it a bit my comment on Ted's page but not specifically.  What your butt-dyno is telling you is acceleration, which is  motor torque * gear ratio / tire size / vehicle mass.  If you don't know the gear ratio, you have know way of feeling the motor torque,  People often look a the motor torque and think wow that should really accelerate hard, but actually motor torque has nothing to do with acceleration, it is all about wheel torque.  It is funny but even many magazine articles and TV Shows (Top Gear In particular) talk about how torque from a motor or engine is important, when in fact it has very little to do with actual performance.  A Torquey motor would actually best describe a motor that has a nice wide flat torque area, so that you can actually remain in its "peak torque" range for a wide range of vehicle speed without having to change gears, or perhaps more commonly a motor that has high torque at low RPM, so you don't have to rev the engine that much from idle before you can release the clutch and get moving really well.

As the graph that tyskmoped posted, a gearbox on a small engine can produce more wheel torque than the single gear of the Zero does, and assuming both vehicles are about the same weight the small gas engine should accelerate harder.  The big difference is that the gas engine torque drops off and you need to shift gears as speed increases, the Zero motor doesn't, so the Zero will accelerate faster than the gas bike when you are in that speed range. In fact I believe that the acceleration is more than you expect which makes it feel like it is actually accelerating faster than it was at lower RPM which is simply not the case.  This leads to the feeling that I admit everybody gets, that the Zero's accelerate harder at 30-60mph than they do from 0-30mph, when in fact the acceleration is very linear from 0-60.

One thing that has been brought up in this thread is that why no motorcycle dyno plots from electric motorcycles start at 0 RPM.  It has been my experience that dyno's control loops and torque estimation are tuned for 15mph and higher.  Below that the eddy current braking and roller speed are changing too quickly for the system to accurately calculate the actual wheel force, probably because nobody really cares about power below 10mph on a gas bike since you are typically slipping the clutch at those speeds if you are trying to get the fastest acceleration anyways.

Another thing that this thread has brought up is weather torque vs hp is more important to acceleration.  As I mentioned above neither of those things on their own gives you any information about acceleration, you need some information about wheel speed , and possibly gear ratio to with it (and the assumption vehicles have similar weight and wheel size).  What matters for acceleration is wheel force. That is either motor torque * gear ratio / wheel size, or motor power / rpm *gear ratio / Wheel size. Having a motor torque curve vs speed for both vehicles, or a motor power vs speed for both vehicles makes an easy comparison, but unless you have such a curve, there really isn't any way to compare 2 vehicles.

-ryan

[Doug S]

Believe what you like but the same vehicle with more horsepower will accelerate faster. Even if the motor has only 10% of the torque, because at same wheel speed you will have more wheel torque if geared for same top speed.

Um, again, no. I'm not trying to argue with you, or make you feel bad, I'm just correcting you. You persist in denying what any Physics 101 class in any college could teach you has been known and accepted for literally 500 years now: Force = mass times acceleration, F = ma. Isaac Newton formulated the law and everyone from high school Physics teachers to every engineer around to NASA understands and agrees that it's true. It's not power that accelerates an object such as a vehicle, it's force, or its rotational analog, torque. High power only becomes necessary as energy is drained from the system at a high rate of speed (such as aerodynamic drag becoming very large at high vehicle speeds), and has to be replaced. That's why power is so important to racing vehicles, which need to attain the highest speeds possible, but torque is far more useful at lower (street-legal) speeds.

Hit up wikipedia or Google and learn some facts. Reality is a pretty nice place to live.

[chdfarl]

This brings up a good point, and I allude to it a bit my comment on Ted's page but not specifically.  What your butt-dyno is telling you is acceleration, which is  motor torque * gear ratio / tire size / vehicle mass.  If you don't know the gear ratio, you have know way of feeling the motor torque,  People often look a the motor torque and think wow that should really accelerate hard, but actually motor torque has nothing to do with acceleration, it is all about wheel torque.  It is funny but even many magazine articles and TV Shows (Top Gear In particular) talk about how torque from a motor or engine is important, when in fact it has very little to do with actual performance.  A Torquey motor would actually best describe a motor that has a nice wide flat torque area, so that you can actually remain in its "peak torque" range for a wide range of vehicle speed without having to change gears, or perhaps more commonly a motor that has high torque at low RPM, so you don't have to rev the engine that much from idle before you can release the clutch and get moving really well.

First I should say that I've been a mechanic, racer and motorcyclist for between 10-20 years respectively so I know how to calculate torque, HP and that rear wheel numbers are quite different than engine/motor numbers.

One thing that we've discussed was if the "claimed numbers" were motor or rear wheel. I feel that Richards post put that to rest since the SRs tested ( chassis dynoed/rear wheel ) numbers were not only consistent with but over the claimed numbers. I feel comfortable saying that if that is the case with the SR then its likely the same with the other Zeros. So in that case the Zero S that I rode would be putting down around 60ft-lbs with a 400lb machine. That is quite close if not on the money with a modern 600cc sportbike. Now since the torque is measured at the rear wheel then gearing is no longer a factor since all parameters are set ie.. each bike has its final ratio and any gear position locked in and they are both on par ( close enough ). A similar foce pushing a similar weight should have a similar outcome, no? I know that the gas engine is spinning at 6-8k rpm but that's its power band where the electrics is said to be 0-6000k rpm.
I've read you comment on Teds page twice now and it really doesn't answer any question for me. The things that im discussing aren't quite as subjective as how it feels to me. Its does the wheel lift or tire break loose. Cortezdtvs bike does without doubt but sadly I never rode it  and we know that the amps is related to the torque but even the Fx that I rode lifted at 20mph.

Wow its time that I stop! Reading and writing these long drawn out posts that seem to go nowhere is exhausting 

[Cortezdtv]

I refer to it as pushing down rather than "lifting" like you do on a fx

Chd where are you from?