Tiltback/Power/Cut Off

[Mono]

50 minutes ago, KingSong69 said:

hefty accelerating into tiltback

seriously? 

[US69]

2 hours ago, Mono said:

seriously? 

yip.....

Tiltback needs power.....was on low batterie....

on gW's tiltback on very high speed can run into total cutout, also.....

[Mono]

1 hour ago, KingSong69 said:

Tiltback needs power

it doesn't, it only readjusts the pedal angle at which the wheel doesn't change speed  but that's a different thread, feel free to chime in 

high speed and low batterie is anyways more than enough to explain a cut out...

[US69]

8 hours ago, Mono said:

it doesn't, it only readjusts the pedal angle at which the wheel doesn't change speed  but that's a different thread, feel free to chime in 

high speed and low batterie is anyways more than enough to explain a cut out...

No...thanks...:-)

we discussed that just some days before....it did not only happen to me because of tiltback, also a few others have experienced cutouts because of it......

 And an easy tip of you dont believe it....use the wheellog watt tracking, set the tiltback to 10 kmh and see the values when u drive into the tiltback :-)

 

[Mono]

@KingSong69 I can see nothing in the thread which gives actual evidence and Fabian doesn't seem to be convinced either. The energy consumption claim seems to be based on the idea that "when the pedals are tilted back it is essentially lifting you slightly higher", which is actually outright false.^1 So I am really interested, where does this idea actually come from? I don't like to be the victim of false convictions and I am always eager to learn and correct my misconceptions. 

What is your take on the question how tiltback actually comes about? Would you agree that it is nothing else than the change of the horizontal pedal adjustment angle to a negative value?

^1 It turns out that CoG of the wheel and of the driver go down when the wheel tilts back and the driver does not change the posture. It is also noteworthy that the wheel cannot do many things, in fact it can only control its spinning speed. That is it can accelerate (by applying more torque) or slow down (by applying less torque or even inverse torque), and that is it. The notion of lifting weight has hence in the end to be traced back to the question of acceleration or deceleration.

[Laenas]

I'll try to jump in on this tilt back subject.

DISCLAIMER: I'm mostly terrible at science related stuff, so take this with a grain of salt. I might be wrong, but then you can simply shed some light for me  

First of all, we probably all agree that the wheel "functions" (operates) by always trying to keep the pedals level. When you ride on it, this translates in the wheel always trying to stay under you. As soon as you lean in one direction, the wheel will move (accelerate in one direction) to try to "catch" you. If you keep leaning, it will continuously move forward in a never-ending attempt to catch you and sit under you. If the laws of physics allowed it and if we had no friction and no forces acting against this movement, it would mean that the wheel accelerates infinitely.

Now... based on the above, the wheel cannot actually decelerate. If it did decelerate even for a second, you would fall, because the wheel would essentially stop in it's quest to "catch" you. So these things never have an actual top speed. What they do have is a technical limitation on how fast (and how quick) it can draw power, spin etc. - and this limitation changes not only from device to device, but also varies at different battery charges, battery ages, temperatures and so on and so forth.

Yes, there is a way that the wheel can "brake" or decelerate. It's the tilt-back. The way it works (and correct me if I'm awfully wrong here) is that it accelerates much faster that what would be needed to "catch" you. In doing so, the wheel effectively accelerates past you and in front of you, and induces a forced lean back. We don't really get to see this fully in action because usually we change our posture as soon as tilt-back happens: either break ourselves because of the "oh shit, I'm going to fast" feeling (and thus help the wheel get in front of us) or adjust our legs and posture in such a way that we keep leaning forward juuust a bit so we "ride the tilt-back".

It's hard to do a perfect experiment, because as living things, we are designed to react. As soon as something changes for our legs, we will react in one way or another, for the simple act of balancing ourselves, if nothing else. However, if we were to stay in exactly the same position and not react to the tilt-back at all (no changes in posture, as if we were a lifeless stick), I think the wheel would quickly accelerate past us and thus slow us down, as it was designed.

So on the subject of "does tilt-back take more energy consumption", I think it truly does, and a lot more. When tilt-back happens, it must do a big burst of acceleration to come under you and then ahead of you. It's absolutely the only way that the wheel can try to slow you down. If you don't listen to the beeps and to the tilt-back, the wheel is forced (by the nature of how it operates) to keep going forward and to keep trying to catch you. Until the technology can't take it anymore and you get a cut-down, that is

[Mono]

@Laenas, I can agree with most of what you say. One point which seems not clear though is that any deceleration goes precisely the way you describe the tilt back. Initially the wheel moves (accelerates) in front of the CoG and then deceleration will take place. This is not specific to tilt back at all and there is no factual distinction between "braking yourself" when tilt back sets in and "the wheel braking via tilt back".

Moving the wheel in front of the driver is not particularly energy costly, it could even be energy neutral if the introduced speed differential between wheel and driver is taken from the wind resistance of the drivers body.

On the other hand, if tilt back sets in smoothly and expectedly, one can keep driving with constant speed by adjusting the feet to the new horizontal neutral angle and thereby preventing the wheel from accelerating to the front. While it feels exhausting to the driver due to the uncomfortable position, I see no reason to believe that it takes any relevant amount of additional energy or torque reserve from the wheel.

[US69]

13 minutes ago, Mono said:

@Laenas, I can agree with most of what you say. One point which seems not clear though is that any deceleration goes precisely the way you describe the tilt back. Initially the wheel moves (accelerates) in front of the CoG and then deceleration will take place. This is not specific to tilt back at all and there is no factual distinction between "braking yourself" when tilt back sets in and "the wheel breaking via tilt back".

Moving the wheel in front of the driver is not particularly energy costly, it could even be energy neutral if the introduced speed differential between wheel and driver is taken from the wind resistance of the drivers body.

On the other hand, if tilt back sets in smoothly and expectedly, one can keep driving with constant speed by adjusting the feet to the new horizontal neutral angle and thereby preventing the wheel from accelerating to the front. While it feels exhausting to the driver due to the uncomfortable position, I see no reason to believe that it takes any relevant amount of additional energy or torque reserve from the wheel.

My last take on this, as most of our arguments are allready in the other post...so here one more:

 

There is a also a (proving)video testing an MCM3 on a "teststand" testbelt..it is with weighted with stones on the pedal....and secured!

As the wheel gets empty...at about 20% batterie...it is running into tiltback as security.

So what happends: As the wheel in the teststand(belt) is not driven by a human, but by "stones" and belts and screws etc...

The tiltback gets out as that what it is: An accelearation....as this wheel is now .....instead of tiltbacking...running faster and faster and going into a cutout!!! because it can not overcome the pressure from the teststand

So what is a tiltback? A tiltback is nothing other than applying !force! on the wheel...letting it working against your pressure on the pedals! 

What you are saying...that its only "a different angle" is only when you are adjusting your wheel ln the app while standstill.

And again: Take the wheelog app....set tiltback to 10kmh.....goto 10kmh and drive on 10 kmh against the tiltback, and just look at the watt numbers compared to driving at 10kmh without tiltback.

[Laenas]

2 hours ago, Mono said:

@Laenas

Moving the wheel in front of the driver is not particularly energy costly, it could even be energy neutral if the introduced speed differential between wheel and driver is taken from the wind resistance of the drivers body.

Thanks for your reply!

I agree with the rest of your points, but I highly disagree with the energy cost of moving the wheel in front of the driver.

We've hijacked this thread entirely... but let me see if I can try to explain my thoughts. Again, if I'm wrong, let me know guys.

When you are leaning forward and your legs/feet are behind you, your body is in a "falling" motion. What keeps you from falling is the motor that keeps running behind you to catch your body. If the motor stops running, the inertia will not cause it to come under you. It doesn't work like that. Friction (and a bunch of other forces that I don't know how to name) will slow the wheel down and you will fall forwards. Considering this is on an even ground, there is absolutely no way for the wheel to come under you and then in front of you without accelerating - and this acceleration requires more energy, by the nature of the word.

The wheel must essentially counter all your leaning and "force itself" ahead of you. If you are leaning forward, this action will only happen with an increase in power.

--- I can see it being a different conversation if you are going downhill (steep incline). In this situation, I would imagine the wheel must work to balance you and slow down. Therefore, if it stops the power suddenly, the physics would probably make it accelerate past you - and keep going while you fall backwards. Not sure if this makes too much sense though ---

[Mono]

3 hours ago, KingSong69 said:

There is a also a (proving)video testing an MCM3 on a "teststand" testbelt..it is with weighted with stones on the pedal....and secured!

As the wheel gets empty...at about 20% batterie...it is running into tiltback as security.

So what happends: As the wheel in the teststand(belt) is not driven by a human, but by "stones" and belts and screws etc...

The tiltback gets out as that what it is: An accelearation....as this wheel is now .....instead of tiltbacking...running faster and faster and going into a cutout!!! because it can not overcome the pressure from the teststand

Right, more acceleration is exactly what we expect if we change the horizontal pedal adjustment while keeping the current pedal tilt constant. That the wheel can run faster and faster means that it does have enough torque to overcome the resistance of the testrig, which is rather a good sign, or a deficiency of the testrig, depending on viewpoint. That it cuts out is almost inexcusable, it should rather run out of torque. 

Quote

So what is a tiltback? A tiltback is nothing other than applying !force! on the wheel...letting it working against your pressure on the pedals!

Tiltback is first and foremost changing the horizontal pedal adjustment neutral point to a different value (of course it could change the entire response curve as well). That is why the wheel gets a tilt when we continue driving with the very same speed. Now if we then push the forefoot down to level the pedal horizontally, the wheel will accelerate, just as it always accelerates if we push the pedal down from neutral position.

Quote

What you are saying...that its only "a different angle" is only when you are adjusting your wheel ln the app while standstill.

Right, you can adjust the angle in the app (I don't think you need to standstill for this, depending on the wheel) and this angle is dynamically modified by tiltback. One is done manually, the other is done by the wheel depending on speed and other parameters.

 

1 hour ago, Laenas said:

When you are leaning forward and your legs/feet are behind you, your body is in a "falling" motion. What keeps you from falling is the motor that keeps running behind you to catch your body. If the motor stops running, the inertia will not cause it to come under you.

Of course, stopping the motor will not lead to controlled braking but to a faceplant. The scenario I was considering was when the motor continues to push with the same torque. In this case, increasing wind resistance of the body (e.g. by spreading the arms widely) can initiate a brake manoeuvre without the need to accelerate the wheel or input any additional power. 

Quote

It doesn't work like that. Friction (and a bunch of other forces that I don't know how to name) will slow the wheel down and you will fall forwards. Considering this is on an even ground, there is absolutely no way for the wheel to come under you and then in front of you without accelerating - and this acceleration requires more energy, by the nature of the word.

The wheel must essentially counter all your leaning and "force itself" ahead of you. If you are leaning forward, this action will only happen with an increase in power.

First, this is entirely unrelated to tiltback. It is the question of how a braking manoeuvre is initiated. Second, no , see above. Third, yes  moving the wheel in front of the body usually takes some energy, but I reckon this is only a fraction of the energy which is needed to keep the wheel and driver going at high speed in the first place. I admit this is not immediate obvious to quantify and it also seems to depend on how quickly one wants to move the wheel in front of the driver. However, to initiate a slow down, it is sufficient to move the wheel only a very small amount relative to the body. Like the inverted pendulum, this is not a stable system, a small initial move, if not corrected, will lead over time to an arbitrary large effect. That is, in principle the needed energy can be made arbitrarily small.  

[Laenas]

27 minutes ago, Mono said:

Of course, stopping the motor will not lead to controlled braking but to a faceplant. The scenario I was considering was when the motor continues to push with the same torque. In this case, increasing wind resistance of the body (e.g. by spreading the arms widely) can initiate a brake manoeuvre without the need to accelerate the wheel or input any additional power.

The wind resistance makes perfect sense, if it's a very strong force, like if you use some sort of wings to slow your body very fast. But I thought we are not talking about such extreme scenarios. In the absence of any powerful external force (as is the case for any practical uses for the wheel), keeping the same torque will definitely not initiate a tilt-back.

You're definitely better at science than me, so it's hard to find my words to prove my point. But I think we are all arriving at the same simple and direct conclusion: that it does indeed take more power -  quantitive aside, because we don't know how much more exactly - but certainly more power in order to initiate a tilt-back.

All this aside though, I am appreciating the mental exercise of this topic.

[Mono]

4 minutes ago, Laenas said:

The wind resistance makes perfect sense, if it's a very strong force, like if you use some sort of wings to slow your body very fast.

It does not need to be strong at all. As said above, the system is unstable in the sense that if the driver doesn't correct for all the small external forces which come in, we will see quickly either a face- or buttplant. I am pretty sure the time frame for this is seconds, not milliseconds and not minutes. Only a small change (spread arms, assuming at least moderate speed) then will make the buttplant the much much more likely outcome than the faceplant still with no further corrections applied.  

4 minutes ago, Laenas said:

But I thought we are not talking about such extreme scenarios. In the absence of any powerful external force (as is the case for any practical uses for the wheel), keeping the same torque will definitely not initiate a tilt-back.

Not sure if this is a mistyping, but I was talking about initiate a brake or slow down, irrespectively of whether tiltback is active or not.

4 minutes ago, Laenas said:

You're definitely better at science than me,

I better be, am a scientist 

4 minutes ago, Laenas said:

so it's hard to find my words to prove my point. But I think we are all arriving at the same simple and direct conclusion: that it does indeed take more power -  quantitive aside, because we don't know how much more exactly - but certainly more power in order to initiate a tilt-back.

Well, still, not quite, sorry, but there is also nothing really wrong to agree to disagree. AFAICS, tiltback in itself does not need (any) additional power, given, say, the driver keeps the speed constant. Or in other words, AFAICS, the power any manoeuvre demands is independent of whether it was driven in tiltback state or in normal state. Maybe there are exceptions, but I can't see them at the moment. 

[Slaughthammer]

39 minutes ago, Mono said:

I better be, am a scientist 

Then you should know, that in a case like this when theoretical evaliuation does not settle the matter, an experiment is the way to go. @KingSong69 had a nice proposal for it!

[Mono]

49 minutes ago, Slaughthammer said:

Then you should know, that in a case like this when theoretical evaliuation does not settle the matter, an experiment is the way to go. @KingSong69 had a nice proposal for it!

AFAICS the theoretical evaluation settles the matter pretty well in this case. The law of conversation of energy alone seems to settle the case as to whether large amounts of energy go into tiltback. You want to make a bet about the outcome of an experiment? I am in! Having said that, I don't meant to say an experiment wouldn't be help- or useful, even besides from winning a bet  

What I find a little strange though is that @KingSong69 suggests to have seen conclusive data and/or has a proposal for an experiment, but doesn't care to present the data and/or the results of his proposal to his fellow wheelers. The trick to say "if you would do this experiments you would see that I am right" (thereby implicitly trying to shift the burden of proof to one side without making any actual argument) is an old one, not falling for it, even though it is admittedly a nice one 

[Slaughthammer]

If my wheel was supported by any of the logging apps, the data would already be here for everyone to see.

As for my pediction of the outcome, there will be a slight burst of power consumption as the tiltback kicks in, because something has to tilt the wheel back. To give your feet the sensation of tilting back, the torque has to be increased. As mentioned above, applying torque is the only thing this machine can do. As the angular velocity will not decrease considerably in this progress, powerconsumption must rise. How big will it be? Thats the question. the faster you go, the higher it will be (power=torque*angular velocity, given the amount of additional torque needed is always the same).

As a man of practical evatuation I'd say, if that power burst causes your wheel to shut down, you're fucked anyways, because then any small bump in the road will do the same.

[Mono]

21 minutes ago, Slaughthammer said:

something has to tilt the wheel back.

Correct. It's the drivers feet. It is the driver who decides what the angle of the pedals is, it is not the wheel. In fact, the pedal angle is the only input the driver can give to the wheel. The wheel has no way to decide over the angle. It essentially only decides over the reaction to an angle given by the driver.

Quote

To give your feet the sensation of tilting back, the torque has to be increased.

I don't see why that would be the case. The sensation of tilting back is the angle of the pedals that the rider needs to assume to get constant speed. Additional torque means acceleration. The wheel doesn't have the choice to apply torque to the feet but not accelerate or vice versa. 

And it turns out I have experimental results, I just didn't think about them: I have a wheel with max speed of 17km/h. Driving the wheel means basically accelerating and before you even know it being deep in the tiltback. Meaning: when I want to get from A to B with this wheel, I drive in the tiltback most of the time. One gets used to it. Now, for some strange reason, this seems to be the wheel with the best km/Wh ratio I own. Go figure how this goes together with tilt back consuming lots of energy.

[Slaughthammer]

I didn't say riding in the tiltback consumes lots of energy. I said: tilting the Wheel back needs "some amount" (how ever small it may be, but it has to be there) more power then just going on without it. I agree with you, that it makes no difference concerning power consumption if the wheel is tiltet back or not while riding. But in the actual moment the wheel is beeing tiltet back, the motor will consume a little bit more power then it would without changing the angle of the wheel.

But as I said, I think this will be in the scale of additional power needed to go over a really small bump.

7 minutes ago, Mono said:

I don't see why that would be the case.

How else should the rider notice what's going on? there is no other way. The only thing an EUC can do is turn the wheel by applying torque to it. So to change anything in the riding state, like for example the angle the wheel is tiltet, can only be achieved by changing the torque applied to the motor. and I think it is obvious, that decreasing torque will never ever lead to a tiltet back wheel

11 minutes ago, Mono said:

Additional torque means acceleration. The wheel doesn't have the choice to apply torque to the feet but not accelerate or vice versa. 

Additional torque can also tilt the pedals back. Remember good old Newton, actio equals recatio. Doesn't matter it the rotor goes faster forward or the stator becomes unstationary by tilting back.

 

13 minutes ago, Mono said:

The wheel doesn't have the choice to apply torque to the feet but not accelerate or vice versa.

Well, a clever, aware rider will sense this increasing torque and give way by rising his feet. Minimal acceleration will happen, yes.

[Laenas]

4 minutes ago, Mono said:

And it turns out I have experimental results, I just didn't think about them: I have a wheel with max speed of 17km/h. Driving the wheel means basically accelerating and before you even know being deep in the tiltback. Meaning: when I want to get from A to B with this wheel, I drive in the tiltback most of the time. One gets used to it. Now, for some strange reason, this seems to be the wheel with the best km/Wh ratio I own. Go figure how this goes together with tilt back consuming lots of energy.

What you're describing is a far stretch from an experiment... I'm pretty sure there are a huge number of other elements that highly influence the km/Wh ratio of a wheel. Out of the top of my head, it's also influenced by: the profile of the tire, the surface used, the overall inclination of the road for your trip, temperature, wind, riding style (maybe you accelerate and break more often and harder on a faster wheel), battery age, efficiency of the engine, cruising speed, clothes used (do you stop more wind with them?) yada yada yada. It's practically impossible to do an accurate comparison by using this method, IMHO

This being said, I'm not preaching necessarily that riding under constant tilt-back will consume significantly more energy than riding without tilt-back. All I'm saying is: 1 - this example is a not a scientific experiment and 2 - the initial acceleration that is required to induce the tilt-back will consume more energy, by direct comparison to a situation where this initial tilt-back was not performed, but the same speed was maintained. Sorry if this was not clear from the beginning, I hope this was not a case of disagreeing on agreeing the same thing

[Mono]

10 minutes ago, Slaughthammer said:

I didn't say riding in the tiltback consumes lots of energy. I said: tilting the Wheel back needs "some amount" (how ever small it may be, but it has to be there) more power then just going on without it. I agree with you, that it makes no difference concerning power consumption if the wheel is tiltet back or not while riding.

I see, sorry if I misrepresented your point. 

10 minutes ago, Slaughthammer said:

But in the actual moment the wheel is beeing tiltet back, the motor will consume a little bit more power then it would without changing the angle of the wheel.

And if so, the wheel will accelerate a little with this little bit of more power. 

10 minutes ago, Slaughthammer said:

But as I said, I think this will be in the scale of additional power needed to go over a really small bump.

How else should the rider notice what's going on? there is no other way. The only thing an EUC can do is turn the wheel by applying torque to it. So to change anything in the riding state, like for example the angle the wheel is tiltet, can only be achieved by changing the torque applied to the motor. and I think it is obvious, that decreasing torque will never ever lead to a tiltet back wheel

So it seems we are in quite close agreement, and the question we might still not fully agree upon is what we view as cause and what as effect. However it seems to be a matter of viewpoint only. I view the torque of the wheel the rider feels as the effect of the angle the rider presents to the wheel. In my view the wheel applies torque for one and only one "reason": because the pedal's angle deviates from the current neutral position. Tiltback is not application of torque, tiltback is change of the current neural position which will lead to change of torque if (and as a consequence of) the pedal's position remain constant. It seems the simplest model to explain everything we need to explain. And it is quite likely the way how the controller implements matters. Shouldn't change the outcome though.

[Mono]

@Laenas, we can agree to disagree, but I am curious about one thing: what is the difference between a scientific experiment and an experiment? And why is taking measurements from my wheels not counting as experiment, or, as I phrased it, as experimental results?

I didn't claim to make an accurate comparison, as you say. What I wanted to point out is that my observations are more likely than not in contradiction to the claim that tiltback consumes a lot of energy, and even that it consumes a relevant amount of energy. Despite the fact that, as you rightly point out, there are many variables I didn't control for (which, BTW, you cannot know as I didn't mention the experimental conditions). 

[Laenas]

22 minutes ago, Mono said:

@Laenas, we can agree to disagree, but I am curious about one thing: what is the difference between a scientific experiment and an experiment? And why is taking measurements from my wheels not counting as experiment, or, as I phrased it, as experimental results?

I didn't claim to make an accurate comparison, as you say. What I wanted to point out is that my observations are more likely than not in contradiction to the claim that tiltback consumes a lot of energy, and even that it consumes a relevant amount of energy. Despite the fact that, as you rightly point out, there are many variables I didn't control for. 

In my (very humble) opinion: a comparison, study or experiment must be at least somewhat accurate, in order to have any relevant conclusions. And I was merely pointing out that those observations you mentioned are probably not relevant. But they may be, who knows

I'm happy to leave this here (+rep). It's a gentleman's agreement to disagree I guess. In the end, I joined this conversation simply to learn more.

[Mono]

Agreed, this is all about learning to describe reality in the best comprehensible (and accurate) way. That's well worth hijacking an ATGATT thread, isn't it 

[steve454]

Isn't tiltback partly to save the batteries before they get too low?  Like when the battery is at 20% the wheel will tiltback at slower and slower speeds.

It does two things, prevent overspeed, and overdischarge.  To prevent overdischarge, some if not most wheels will permanently tiltback to make it impossible to ride.

It might be a good thing if overspeed tiltback would temporarily stop the wheel completely for a minute or two, to give the rider time to think about slowing down next time.  As a side effect, it would let the batteries recover a liitle.

[Mono]

AFAICS, tiltback serves as a speed limiter that can be set with essentially any desired target speed (including zero) and temporarily or permanently. Now then, a speed limiter can serve several purposes, like preventing high speed cut outs or saving energy when battery is low or preventing (at least to some extends) large battery drains or prevent unauthorised use...

[US69]

my last ever guess now on tiltback, as for me this is the same (worthless) discussion as: "Wheels should be "programmed" not to go over their max Speed, and "just stay" on max Speed".....which is just not doable on SB vehicles.

 

Whenever you think tiltback does not need any power....you should think about how the wheel acts in General!

What are you doing when you drive? You push down the pedals and the wheel does have to work against it by speeding up! If you dont push anymore...the wheel slows down.

A tiltback is nothing more than the wheel working more than on normally driving as it not just have to go to the horizontal stage...it has to go higher and work more against your pressure.....

 

I know/believe that.....from own faceplanting experience.....from Videos where the wheel began speeding up on tiltback....also there have been several reports of others who have experienced high Speed cutouts on GW's by tiltback set to high..... on the GW FB Group it is common sense not to set tiltback to high and warn others to do that.

 

But OK! It is a free world and every one can believe whatever he wants... :-)

 

i just would like to warn ACM or MSuper Drivers to set the tiltback higher than 39kmh! You may  than be experiencing the effect yourself....and that might be the worst proof possible!

If just that is taken away from this discussion.....more than enough for me!

 

9 hours ago, steve454 said:

Isn't tiltback partly to save the batteries before they get too low?  Like when the battery is at 20% the wheel will tiltback at slower and slower speeds.

It does two things, prevent overspeed, and overdischarge.  To prevent overdischarge, some if not most wheels will permanently tiltback to make it impossible to ride.

It might be a good thing if overspeed tiltback would temporarily stop the wheel completely for a minute or two, to give the rider time to think about slowing down next time.  As a side effect, it would let the batteries recover a liitle.

No, tiltback is used to slow you down before your wheel reaches his maximal available Speed...Some Wheels use this always (KS for example has it on advertised max Speed, always)...some wheels use that optionable and let you set it like you want(GW's)...and nearly all! wheels have that implemented to slow you down on very low Batterie, as with low Batterie you do not have the energy left to go fast on the wheel anymore!

But it is not meant as Batterie protection...or better say that is not the main Point of tiltback......