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Sudden break behavior


maxkan

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What happened in my case if that the wheel shut down, I fell on my back and the wheel rushed forward as if its a bowling ball.

My wheel is Inmotion V8. Is that usual behavior of every wheel or is that because the engine was not powerful enough? Are there wheels that can stop suddenly and do not shut down if you lean back sharply?

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8 minutes ago, DanCar said:

Where you at max speed and leaning more than 30 degrees?  Was it a downhill?  Was the battery fully charged?

Maybe 5 km/h less than max speed, slight downhill, almost flat. Fully charged. Not sure how much leaning, but a lot. Basically there was a car suddenly arrived from the side blocking my path. I tried to do something similar to snowboarding stop (but with no turn) but instead got a bowling ball 

Edited by maxkan
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Thats the battery not having enough power, and thats more or less a behaviour of „underpowered“ wheels.

The V8 is only able to produce 20 Amps continuous, while more powerfull wheels with bigger batterys are able to produce 60 or even 80 Amps cont. As braking and acceleration are amp (torque) related, this can happen on a V8. If you owerpower it, it normally starts fast beeping, if the overpowering happens much to fast it skips the beeping and shuts off directly.

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1 hour ago, maxkan said:

...slight downhill, almost flat. Fully charged. ...

The wheel brakes by regenerative braking.  If the battery is full, it has no place to put the energy so stops braking and "rushes forward".  Just a guess on my part.

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The V8 "unfortionately" only has a 2p (2 cells in parellel) configuration - 4p or more can take more braking current (braking power).

Generally the stronger wheels should break better - there are youtube videos with braking comparisons/tests. Imho the V8 was not so bad in comparison?

The battery charge also should have an impact (although i can't remember tests/reports/discussions). Lower charges (lower battery voltage) should (at least theoretically) allow more braking current (braking force) - anyway as @DanCar mentioned, if the battery is too full the wheel will just stop braking... ;( Is often reported from people driving downhill with a fully charged wheel - but there the wheels warns (beeps) before and tilts back. Don't know if a single strong braking manouver is enough to trigger this overcharge cut-out by the firmware?

"Older" wheels (?before the V8 and comparable?) tended too blow the mosfets while stronger braking - can't remember recent reports of "newer" wheels. This should be a problem of the past?

Imo generally the braking performance of EUCs is not overwhelming - a comparison with bikes would be great. My feeling would say that bikes easily outperfom EUCs...

As it is easy to overlean EUCs while braking this should be trained "safely" to get a feeling of the possibilities - with much safety gear in a safe enviroments! ... and maybe some wheel recovery time inbetween to not overburden the MOSFETs...

From the new wheels just the Z10 was reported to have a bad braking behaviour - something like no/insufficient braking downhill at slower speeds? Was/is afair firmware related - maybe resolved by a firmware update inbetween?

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This behavior sounds like what I get when overpowering the wheel - either acceleration or braking.

You might expect that you'd hit a point where the wheel can't give as much power as you want.  e.g. you want power X and the wheel supplies power X-d, where "d" is some delta less than you want.  You might expect that in this situation, you had better ease up or you would fall off, forward or back.

But this is not what happens!  Instead, the wheel gives up and provides ZERO power, abruptly falling out from under you.

I can force this to happen with abrupt braking (even if the battery isn't fully charged).

I've had this happen unexpectedly twice.  Once soon after getting really comfortable with the wheel, I tried to accelerate as hard as possible.  I started to accelerate and the wheel dropped me violently on my face.  (Thanks for helmet!)  The other time, I was coming down a steep hill at about 15mph (no, the battery was not fully charged) and tried to break hard at the bottom.  The wheel dropped me stunningly hard on my ass.  Tailbone hurt for several weeks.

I've been told that this won't happen (or at least is less likely) with a newer and/or more powerful wheel.  I suspect that every wheel has its limits.

Now when I ride, I try to be conscious of the power burden of aggressive acceleration/deceleration.  I REQUEST power from the wheel, I don't DEMAND it.

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As others already have said, it's the small (2p) battery that limits the available power. Shouldn't happen with 4p wheels, for example.

Or the tire simply slipped:efee47c9c8: As soon as you lose traction, the wheel loses balance, it's not like a bike that can come to a sliding stop.

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  • 2 weeks later...
On 10/16/2018 at 5:28 AM, maxkan said:

What happened in my case if that the wheel shut down, I fell on my back and the wheel rushed forward as if its a bowling ball.

Before you fell off, did the pedals give in under your heels and tilted backwards or did they stay (more or less) horizontal? Only in the first case it is likely to be a power limitation of the EUC.

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On 10/24/2018 at 7:26 AM, Mono said:

Before you fell off, did the pedals give in under your heels and tilted backwards or did they stay (more or less) horizontal? Only in the first case it is likely to be a power limitation of the EUC.

I was able to easily reproduce the problem.

Setup: You're standing on your EUC near the fence holding it with your both hands, the fence is behind you.

Action: You're trying to push EUC forwad, away from the fence using your legs

Effect: At some point the pedals just give up and EUC shuts down. The only thing that prevents you from falling is your hands holding the fence

Reproducible 100% of the time

 

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On 10/16/2018 at 1:06 AM, Chriull said:

Imo generally the braking performance of EUCs is not overwhelming - a comparison with bikes would be great. My feeling would say that bikes easily outperfom EUCs...

I tested this with my new disk-brake equipped Vanmoof with 28 inch by 2.0 inch Big Apple tires versus my KS16S versus MSuper V3S+, from about 20 mph. It's estimated from sidewalk crack to sidewalk crack.

On paper the EUCs stand no chance at all against the bike but surprisingly they all did about the same in raw braking. Astonishingly the MSuper is the best braker; it easily feels the worse but no it stops great...it just feels like a long distance.

Unless you ride to always cover your brakes, I think the EUCs beat bikes in emergency braking everytime due to the EUC's "instant on" power, that is you throw the wheel out in front of you and brake. That ability has the EUC beat the bike every time.

Finally, EUC braking isn't dangerous because nothing bad happens if you're leaning back whereas on a bike there's always some reserve; a locked front wheel is an automatic injury.

Bottom line; raw power all about the same, EUCs win hands-down in every other situation.

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1 hour ago, LanghamP said:

I think the EUCs beat bikes in emergency braking everytime due to the EUC's "instant on" power, that is you throw the wheel out in front of you and brake. That ability has the EUC beat the bike every time.

Doesn't work this way. That's exactly what I did. The wheel just shuts down. I guess because all the braking is made by the engine and its limited and would just be overloaded

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6 hours ago, LanghamP said:

I tested this with my new disk-brake equipped Vanmoof with 28 inch by 2.0 inch Big Apple tires versus my KS16S versus MSuper V3S+, from about 20 mph. It's estimated from sidewalk crack to sidewalk crack.

On paper the EUCs stand no chance at all against the bike but surprisingly they all did about the same in raw braking. Astonishingly the MSuper is the best braker; it easily feels the worse but no it stops great...it just feels like a long distance.

Unless you ride to always cover your brakes, I think the EUCs beat bikes in emergency braking everytime due to the EUC's "instant on" power, that is you throw the wheel out in front of you and brake. That ability has the EUC beat the bike every time.

Finally, EUC braking isn't dangerous because nothing bad happens if you're leaning back whereas on a bike there's always some reserve; a locked front wheel is an automatic injury.

Bottom line; raw power all about the same, EUCs win hands-down in every other situation.

Thanks for testing!

My google search for EUC braking brought me to https://www.youtube.com/watch?v=LZTcQrNtxcI - that tests does not seem to hazardous and the drivers not too "trained" and they reach braking decelerations from 3,5-6,2 m/s²!

From other sources for bicycles i found that 6 m/s² are easily reachable and at ~5 m/s² the risk of falling rises drastically - so EUCs should really at least be comparable.

... and if modern (with big battery packs) EUCs sustain braking without (too?) easy overleans, that's a very nice "insight".

Contrary to bicycles the missing of any feedback from the EUC is what leaves a bit of uncomfortable feeling...

 

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11 hours ago, maxkan said:

Action: You're trying to push EUC forwad, away from the fence using your legs

Effect: At some point the pedals just give up and EUC shuts down.

Can you be more precise what you mean by "shuts down"? Is the wheel off afterwards? 

If the unfolded pedal angle exceeds a certain threshold away from 0º horizontal, the wheel will stop to activate the motor to prevent the typical spinning-out-and-crazy-dance when lying on the side or standing on the fender. Usually, the motor reactivates when the pedals angle is recovered to upright position. This is not the case here?

Edited by Mono
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3 hours ago, Chriull said:

Thanks for testing!

My google search for EUC braking brought me to https://www.youtube.com/watch?v=LZTcQrNtxcI - that tests does not seem to hazardous and the drivers not too "trained" and they reach braking decelerations from 3,5-6,2 m/s²!

From other sources for bicycles i found that 6 m/s² are easily reachable and at ~5 m/s² the risk of falling rises drastically - so EUCs should really at least be comparable.

... and if modern (with big battery packs) EUCs sustain braking without (too?) easy overleans, that's a very nice "insight".

Contrary to bicycles the missing of any feedback from the EUC is what leaves a bit of uncomfortable feeling...

I was braking a damn sight harder than that, with sustained 60+ amp on the MSuper (I don't have any of my other wheel hooked up to WheelLog). Maybe EUCs have more raw braking power? Although bikes have two wheels under hard braking you're not using the rear wheel much.

I will say I had a lot of difficulty on the bike due to the fear of locking up the front, but the disc brakes do have the power to completely overpower the tire. My opinion is bikes and EUCs are comparable and that both are probably capable of overwhelming their tires (certainly bikes can and newer EUCs).

 

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On 10/31/2018 at 1:46 PM, LanghamP said:

My opinion is bikes and EUCs are comparable and that both are probably capable of overwhelming their tires (certainly bikes can and newer EUCs).

With a 26" bicycle on dry asphalt my braking limits come from keeping the rear tire down. I know because I failed once and did a rollover even on an unpaved road.

Edited by Mono
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1 hour ago, Mono said:

With a 26" bicycle on dry asphalt my breaking limits come from keeping the rear tire down. I know because I failed once and did a rollover even on an unpaved road.

Facepalm :angry:

Of course EUCs can brake harder than a bicycle (assuming a strong motor) because the rider doesn't have to worry about flipping over his "front" wheel! The EUC rider can move his center of gravity to well below than a bicyclist can, as there is no frame.

What I had mistakenly said about "throwing the wheel out in front of you" is really leaning back in a way no bicyclist can match.

Think about the converse; is it possible to brake so hard on an EUC that you "get flipped over the handlebars"? No, so the limit is the motor and the tires. On a bicycle the limit is often being flipped over the handlebars.

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13 hours ago, LanghamP said:

On a bicycle the limit is often being flipped over the handlebars.

1) You can use 2 brakes on a bicycle, rear brake first

2) You can shift you gravity center backwards by moving your ass behind the sadle

 

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17 hours ago, Mono said:

Can you be more precise what you mean by "shuts down"? Is the wheel off afterwards? 

If the unfolded pedal angle exceeds a certain threshold away from 0º horizontal, the wheel will stop to activate the motor to prevent the typical spinning-out-and-crazy-dance when lying on the side or standing on the fender. Usually, the motor reactivates when the pedals angle is recovered to upright position. This is not the case here?

It shuts down completely, you'd have to turn it on again to reactivate

Also as the angle is pretty big, after the shutdown the wheel would fly forward and you'd fly back on your ass so it doesn't really matter if it would reactivate or not

Now imagine if you emergency break this way in front of a group of children... Bowling

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8 hours ago, maxkan said:

It shuts down completely, you'd have to turn it on again to reactivate

This I would consider to be a defect. It may be a design fault or a defective wheel. I am hesitant to try to replicate the behaviour with my wheel, in particular as one of the motor connectors on the motherboard already looks burned (which I have seen in a picture of another motherboard as well).

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8 hours ago, maxkan said:

1) You can use 2 brakes on a bicycle, rear brake first

Not using the front brake immediately will increase the stopping distance.

8 hours ago, maxkan said:

2) You can shift you gravity center backwards by moving your ass behind the sadle

True, though the woman in the vid doesn't seem to hit the brake particularly hard. I doubt you can fully prevent a rollover by shifting the weight on most bicycles. Even motorbikes can be flipped and they have a much lower CoG.

 

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9 hours ago, maxkan said:

1) You can use 2 brakes on a bicycle, rear brake first

2) You can shift you gravity center backwards by moving your ass behind the sadle

 

If you have time to prepare by moving your body parts then that's not really an emergency stop.

How long does it take to stop when 

1. Hands are in natural position (not over brakes).

2. Butt is on seat.

In contrast an EUC already has you in emergency braking position...you don't have to move a thing.

Also, you have a crummy wheel, 'cause it keeps dumping you at low speeds. If your crummy wheel gives you crummy braking distances or dumps you, then it's logical that you need to find a bike that has crummy brakes.

That way, you can compare your crummy wheel with your crummy bicycle, and then you can state with pretty good accuracy which brakes better. A crummy EUC or a crummy bicycle?

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