Terrible accident on Ninebot Z10

[Igor Rz]

Today's ride ended with a small accident of a friend, I leave to evaluate what could be the reason (action starts at 3:09)

 

 

 

 

 

 

 

 

Edited May 27, 2019 by Igor Rz

[Seba]

29 minutes ago, Igor Rz said:

Today's ride ended with a small accident of a friend, I leave to evaluate what could be the reason (action starts at 3:09)

For me it looks like an overlean when accelerating. Happens quite often to inexperienced and somewhat unruly riders that don't know the limits of their EUCs. Hope your friend is OK.

[Unventor]

I tend to agree with @Seba. Now I didn't make what wheel you friend is using. 

I also had an interesting expirearance with my KS18L where I were to aggressive with acceleration, but my wheel did an hard tiltback and I manage to keep it under control. At the time I was at 40ish% battery. 

That is one reason why I like my KS18L. It tries to keep me within safety margins to avoid above accident. 

[Guest PogArt Artur]

2 hours ago, Igor Rz said:

Today's ride ended with a small accident of a friend, I leave to evaluate what could be the reason (action starts at 3:09)

 

 

 

 

 

 

 

 

Thanks for sharing, I hope your friend is ok after all. 

[Rehab1]

Glad he is ok.

My 2 cents: after your friend passed the elderly couple he transitioned to the grass then onto the road. He appeared off balance through that entire sequence and never gained full control.

 

[Unventor]

1 hour ago, Rehab1 said:

Glad he is ok.

My 2 cents: after your friend passed the elderly couple he transitioned to the grass then onto the road. He appeared off balance through that entire sequence and never gained full control.

 

From the stills you made @Rehab1, I think it kinda explains why I could save my wheels reaction.

As you pointed out he has a forward lean out passed the wheel. But when he starts to lean further to accelerate the wheel cannot keep up. 

When I ride I partly lean partly push with my foot, as if I am standing on my toes. This mean I don't tend to risk overlean as much, however the wheel will kick in with tiltback, that kinda surprised me as I done that level of acceleration before, but at 80-95% battery capacity. 

Learn how to ride in snowy condition helped me not to lean out passed the wheel as much as you want to have your center of gravaty if you get what mean as straight above the wheel at all times. This helps to prevent wheel from sliding away under you in slippery conditions (snow, gravel, loose sand, sand on top of hard surface, ice, mud, wet leaves, road markings in the wet, wet grass, just to mention a few on top of my head😁). 

Edited May 27, 2019 by Unventor

[Marty Backe]

This has already been discussed a lot on Facebook. I thought the consensus is that it's a simple overlean situation.

When I view the video, I see someone that is going fast and then leans into it for acceleration.

I recommend that people who like to aggressively lean forward for fast acceleration only do so when the wheel is basically stopped. At least then they won't fall to hard.

If the wheel is already moving fast and you lean into it, you are creating extreme loads on the wheel and if the the system (motor power and available battery energy) is already near maximum capacity, the wheel will cutout.

I have always advocated a Pebble watch so that you can learn the power consumption that your wheel requires. I can tell you that when you lean into an acceleration, there is a huge spike in power consumption. I will never lean into the wheel once I'm at speed. Unless I'm close to walking speed, my accelerations and decelerations are slow.

It's amazing the lack of knowledge that I continue to see out there on how our wheels work and their limitations. 

[Unventor]

43 minutes ago, Marty Backe said:

It's amazing the lack of knowledge that I continue to see out there on how our wheels work and their limitations. 

I can only agree with this. Now part reason is the manuals supplied by manufactor do not explain this, other part is it kinda look easy when you see a skilled rider on YouTube. 

This is one aspect why I think a riders license will be good overall both for traffic safety and to expose the EUC more to mainstream public. 

I know this is a heated topic, but I rather enjoy my wheel than see government shoting down options to use EUCs as we see partly happening in Europe. 

Better to have mandatory education than people getting hurt and at expense of options for public use for others in the process. 

Note: I am no Saint, I had my accidents too. But I didn't see accident shared so much as in the past 6 months on this forum. 

Edited May 27, 2019 by Unventor

[stephen]

1 hour ago, Marty Backe said:

have always advocated a Pebble watch so that you can learn the power consumption that your wheel requires. I can tell you that when you lean into an acceleration, there is a huge spike in power consumption

I have my Pebble on 90amps which does scare me sometimes and stops me going up steep hills on occasions as i slow down as soon as it starts vibrating , 

[Marty Backe]

4 minutes ago, stephen said:

I have my Pebble on 90amps which does scare me sometimes and stops me going up steep hills on occasions as i slow down as soon as it starts vibrating , 

 

I will say that you don't have to immediately slow down, but if my watch buzzes continuously for more than 2-3 seconds I adjust my riding to stop the buzzing.

And because of so much experience feeling the 90-amp alarm when hitting bumps at speed, I try to slow down before hitting a bump that I can see in advance. All this does, is decrease the risk that you'll have cutout type failure.

[stephen]

6 minutes ago, Marty Backe said:

 

I will say that you don't have to immediately slow down, but if my watch buzzes continuously for more than 2-3 seconds I adjust my riding to stop the buzzing.

And because of so much experience feeling the 90-amp alarm when hitting bumps at speed, I try to slow down before hitting a bump that I can see in advance. All this does, is decrease the risk that you'll have cutout type failure.

Yeah i just think I'm over cautious when it comes to off road hills , which probably isn't a bad thing I'm try the 3 2/3 second attempt i wouldn't at speed but on hills I'll be ok, at least I'll just hit the ground lol rather than hit the ground and tumble😁😁😂

Edited May 27, 2019 by stephen

[OUNCESMUSIC]

 A license isn't going to change the fact that people will drive how they want. I'll enjoy my dangerous freedom over peaceful slavery thank you. TPTSB don't need any more of my time, money, or personal information.

[stephen]

13 minutes ago, Marty Backe said:

 

I will say that you don't have to immediately slow down, but if my watch buzzes continuously for more than 2-3 seconds I adjust my riding to stop the buzzing.

And because of so much experience feeling the 90-amp alarm when hitting bumps at speed, I try to slow down before hitting a bump that I can see in advance. All this does, is decrease the risk that you'll have cutout type failure.

Another thing marty i have noticed ,i ride in soft mode mostly and it vibrates more probably due to leaning more for forward lean ,on hard mode it doesn't vibrate as much 🤔

[Unventor]

24 minutes ago, OUNCESMUSIC said:

 A license isn't going to change the fact that people will drive how they want. I'll enjoy my dangerous freedom over peaceful slavery thank you. TPTSB don't need any more of my time, money, or personal information.

That is probably going to work for you... But people around you might see thing differently. 

Being in public traffic means others needs to be able to anticipate what they can expect you doing. 

If you by yourself in a forrest you might have any issues, downtown traffic only works if people abide to some common rules. 

So as I started out this can be a very heated debate, so you have the freedom of choice to ignore my opinion but that will not change anything of my view what I think works best for all not just you. 

I can only recommend you buy an island somewhere where you can live by your rules. 

[Marty Backe]

20 minutes ago, stephen said:

Another thing marty i have noticed ,i ride in soft mode mostly and it vibrates more probably due to leaning more for forward lean ,on hard mode it doesn't vibrate as much 🤔

That's very interesting. I haven't made any associations like that, probably because I'm most in Hard Mode.

But that's fascinating. I need to experiment more with the Soft Mode too so I can see that.

Thanks!

[OUNCESMUSIC]

25 minutes ago, Unventor said:

 

Being in public traffic means others needs to be able to anticipate what they can expect you doing. 

If you by yourself in a forrest you might have any issues, downtown traffic only works if people abide to some common rules. 

....

I can only recommend you buy an island somewhere where you can live by your rules. 

Sure. Abide by common sense VS common rules in my perspective but what do I know and who am I.
My commute encountours the pontificated wooded area into country roads as well as heavy traffic and HWY's.
All about safety with gear and technique around these death battering rams and in general because of inherit wheel limitations.
Promote this to all riders.
I can't recommend you anything but the above. 
 

[Planemo]

7 hours ago, Marty Backe said:

If the wheel is already moving fast and you lean into it, you are creating extreme loads on the wheel and if the the system (motor power and available battery energy) is already near maximum capacity

I absolutely get this. But I still dont understand why wheels should 'cut out'. I am clearly missing something.

If we are travelling at say 95% of a wheels speed and lean foward, I accept that the wheel can only go so fast. But why cant it just say 'we are going warp factor 10 already cap'n, she cannae tak no more' and continue doing what its doing, giving everything its got (I accept that this might not be long - a few seconds or so) rather than just saying immediately 'ah fcuk this, I'm gonna turn off'.

In the first example, surely the rider would feel, at least for a split second, that the wheel wasnt keeping up with his angle of lean. The rider would instinctively back off (also in a split second) and hopefully, if lucky,  save the day, albeit with brown underpants.

The second scenario gives the rider no chance at all.

And this doesnt take into account tiltback. Surely this can be administered in such a way that an overlean is technically impossible?

My brain is struggling.

[Chriull]

5 minutes ago, Planemo said:

I absolutely get this. But I still dont understand why wheels should 'cut out'. 

It does not really - it just can't deliver enough torque anymore to keep one upright.

5 minutes ago, Planemo said:

I am clearly missing something.

Here is everything you never wanted to know about why wheels overlean 

5 minutes ago, Planemo said:

If we are travelling at say 95% of a wheels speed and lean foward, I accept that the wheel can only go so fast. But why cant it just say 'we are going warp factor 10 already cap'n, she cannae tak no more' and continue doing what its doing, giving everything its got (I accept that this might not be long - a few seconds or so) rather than just saying immediately 'ah fcuk this, I'm gonna turn off'.

Yes. The manufacturers could implement sound warnings in the firmware. But the rider has to regard the warning and stop leaning forward/brake.

5 minutes ago, Planemo said:

Surely this can be administered in such a way that an overlean is technically impossible?

No. Just using a stronger wheel and accelerating at slower speeds make overleans go away...

[seage]

13 minutes ago, Planemo said:

I absolutely get this. But I still dont understand why wheels should 'cut out'. I am clearly missing something.

If we are travelling at say 95% of a wheels speed and lean foward, I accept that the wheel can only go so fast. But why cant it just say 'we are going warp factor 10 already cap'n, she cannae tak no more' and continue doing what its doing, giving everything its got (I accept that this might not be long - a few seconds or so) rather than just saying immediately 'ah fcuk this, I'm gonna turn off'.

In the first example, surely the rider would feel, at least for a split second, that the wheel wasnt keeping up with his angle of lean. The rider would instinctively back off (also in a split second) and hopefully, if lucky,  save the day, albeit with brown underpants.

The second scenario gives the rider no chance at all.

And this doesnt take into account tiltback. Surely this can be administered in such a way that an overlean is technically impossible?

My brain is struggling.

It was gonna say it would be nice if the wheel itself slowed down, but then i think we'd see people freefalling off the front of their moving wheels, lmao. 

[Planemo]

So we are saying that the wheels dont actually cut out, its just that they reach their maximum speed and it is in fact the rider who launches themselves off the front of the wheel because they are leaning foward of their CoG?

[Mono]

39 minutes ago, Planemo said:

So we are saying that the wheels dont actually cut out, its just that they reach their maximum speed and it is in fact the rider who launches themselves off the front of the wheel because they are leaning foward of their CoG?

Yes, that sounds like an accurate description. Or in other words, they reach their torque limit which more often happens at larger speed because the available torque decreases with increasing speed.

[svenomous]

I'm not sure how well people understand how the physics of a self-balancing wheel works, nor how fast things will happen (and therefore fail) at the RPMs, velocities, inertias, and rotational moments we're dealing with.  If a rider leans forward and a wheel simply continues to rotate at the same speed it was already at, the rider will fall off the front of the wheel.  The balancing mechanics require the wheel to accelerate to stay "under" the rider.  If the rider leans hard (moves CG significantly forward), the wheel must accelerate aggressively to remain under the rider.  Period.  There's no choice to "just do what you can" or "just don't accelerate any more when at the limit."  It must accelerate, or try to, or the rider will simply fall.  The motor has a torque "margin," and that margin decreases with rotational speed.  The faster the wheel is going, the less margin there is.  In addition, the battery pack's BMS has a low-voltage cut-off that will simply stop the current flow if the pack goes beyond the lower safe voltage limit.  The wheel's mainboard has no control over the low-voltage cut-off and will lose power along with the rest of the wheel when the cut-off happens.  If the torque limit is exceeded, the rider goes down because the wheel is still trying but the motor just can't accelerate fast enough.  If the voltage cut-off happens due to excessive amperage demand when the battery pack is depleted, the wheel will simply go instantly dead, with the same result.  The result is the same, although high-speed footage would probably show a difference in how fast the wheel chassis/pedals rotate away from level and dump the rider when comparing between exceeding motor capability and hitting BMS cut-off voltage.

No wheel can "just slow down" or "just refuse to accelerate further."  It's just not possible.  What it can do is to monitor all the known parameters (voltage, amperage, speed), provide audible warnings (beeping or voice), and as a last resort use tilt-back as a "discouragement."  If pedal angle tilts back 10 degrees while trying to accelerate, acceleration becomes hard to achieve, although a determined rider who is standing with feet sufficiently forward on the pedals can indeed keep the wheel going at that speed, or even make it accelerate further...until the moment of failure.  Not only can tilt-back be defeated on some wheels by turning it off, but it's also conceivable to lean into an acceleration so hard that there's no time to do the tilt-back before failure occurs.

So, when going fast, don't change speeds aggressively via hard leaning, and when the battery pack is very depleted, the same is true even at much lower speeds.

[meepmeepmayer]

@Igor Rz At what speed was this?

Doesn't look like the Z10's speed limit (45?) to me. Then he should not have been able to overlean the wheel that easily! That looks like a normal sporty acceleration at a still reasonable speed. It should have worked!

Maybe it was some stupid current/whatever limiter throwing the rider off?

3 minutes ago, svenomous said:

In addition, the battery pack's BMS has a low-voltage cut-off that will simply stop the current flow if the pack goes beyond the lower safe voltage limit.

I believe EUC BMSes have this disabled specifically so you won't just fall after a millisecond of undervoltage. Early EUCs had hat problem.

[svenomous]

Oh, I thought that EUC BMS still does low-volt cut-off.  So what causes low-battery type failure, then, if not a cut-off?  Is it just that the motor can't get enough amps, but the wheel is actually still powered?

[meepmeepmayer]

No idea. I guess there is something (overcurrent for the individual cells?), but the standard low voltage thing like any standard BMS has is usually disabled for EUCs as far as I read. Maybe a battery related cut-off can even be plain physical? @esaj @Chriull

In this case it might not be battery related. Speed (motor) or something protecting the electronics over the rider.