My first High Speed crash ever and it was on the S22

[Rawnei]

So yesterday I had my first high speed crash ever and it was on the S22 going 65.7kmh. 😅

Let me preface with a few things:

• This was 100% rider error overlean situation, me and @Mike Sacristan was racing and I accelerated too hard at high speed trying to catch up with Mike who was ahead of me, it was dumb and not something I usually do, spur of the moment kind of idiocy...
• ...but also none of my safety mechanisms alerted me of what was about to happen, it's possible that wheel was beeping but I can't hear wheel beeps over the wind wearing a helmet which I think is the usual situation for most riders, I could feel no tilt-back from the wheel, none of my EUC World alarms that I have configured was triggered (I checked the logs and will detail more on this below), I usually rely on EUC World and respect those alarms.
• Both me and the wheel is fine, it was a very "good" fall all things considered.

The crash and resultant damage:

So this happened while riding seated, the fall itself wasn't very dramatic all things considered I put my hands out landed on my left side and slid out it happened very fast and was a bit surreal, I was fully geared and all my gear did a superb job, gear is now damaged from sliding but still usable and not a single scratch on me not even a road rash.

Gear worn: Course Four Seasons 2.0 pants with level 1 Knee and Hip protectors, IXS Classic Urban-ST Motorcycle Textile Jacket with level 2 Back, Shoulder and Elbow protectors, Rollerblade Wristguards over Ski-Gloves (brr winter) and Shark EvoJet helmet (helmet didn't even touch the ground).

Damages to the wheel: I think generally wheel damage is a dice throw and this time I got lucky with the wheel not doing any acrobatics but the S22 is also pretty well built overall, my own 3D printed bumper took most of the damage, I will simply print a new one and replace it, the right pedal got some scraping, my extra motorcycle seat I have on-top got some small bruises which are barely visible and not even worth showing, besides those things the wheel is unharmed, we even did a 40km cruise in the rain afterwards.

Wheel Behaviour:

So again, it's possible that the wheel was beeping but as most riders that ride at these speeds know it's very difficult to hear it over the wind and wearing a helmet, beepers are notoriously bad safety mechanisms at these high speeds, people around you can hear them but not you yourself.

I could feel no tiltback at all, overall the tiltback on the S22 is very weak and difficult to feel and I consider it not a very good safety function to rely on due to this, my point of reference for a great tiltback implementation is the Begode Custom FW by @Freestyler which feels very safe and responsive in comparison to the one on the S22. I actually have a dialogue with KS about tiltback since before this crash and they will be tuning it in future firmware versions so keeping my fingers crossed that we will see improved tiltback functionality on the S22 in the future as I consider a well implemented tiltback to be the best safety feature.

EUC World Logs and Alerts:

I have experimented a lot with alerts in EUC World trying to find the sweet spot on the S22 that roughly matches beeps and tiltback on the wheel, during the crash I had these alerts:

Safety Margin: from my testing anything between 15-18% has roughly been matching wheel safety mechanisms depending on situation so I had this set to 15% as to not get false positives, it has served me fine up until now.

Use wheel alarms (seems to do nothing on S22)

Enable speed limit alarm with 0kmh margin, I have set my speed limit to 66kmh on the S22 which will trigger this alarm, this is dynamic and will match any speed throttling done by the wheel I think (clarification @Seba?), overall a pretty nice alarm to have and not too intrusive sound.

These alerts have served me fine up until now, what is different is that the acceleration was too hard and it triggered none of these alerts.

 

• 1st log snippet this was from a race just minutes before with no crash (race #1), here you can see my alarms being triggered and me backing off when it happens:

datetime

speed

speed_max

voltage

current

power

safety_margin

alarm

gps_speed

 

 

2022-12-29T14:20:37.212+0100	56.49	56.49	113.43	44.96	5100	15	256	58.49
2022-12-29T14:20:38.112+0100	58.45	58.45	114.21	41.46	4735	28	0	62
2022-12-29T14:20:38.950+0100	62.13	62.13	113.59	42.98	4882	27	0	64.5
2022-12-29T14:20:38.983+0100	62.13	62.13	113.59	42.98	4882	27	0	64.5
2022-12-29T14:20:39.075+0100	63.9	63.9	113.17	45.3	5127	23	0	64.5
2022-12-29T14:20:39.223+0100	65.3	65.3	112.17	48.62	5454	22	0	64.5
2022-12-29T14:20:39.376+0100	65.83	65.83	115.48	34.54	3989	19	0	64.5
2022-12-29T14:20:39.549+0100	66.73	66.73	116.05	31.58	3665	25	512	64.5
2022-12-29T14:20:39.962+0100	66.49	66.73	116.37	30.98	3605	27	512	67.54
2022-12-29T14:20:40.705+0100	67.16	67.16	114.18	40.07	4575	17	512	67.54
2022-12-29T14:20:40.926+0100	69.76	69.76	118.14	21.07	2489	17	512	68.38
2022-12-29T14:20:41.423+0100	67.93	69.76	117.11	25.81	3023	21	512	68.38
2022-12-29T14:20:41.927+0100	67.58	69.76	117.56	25.73	3025	15	768	68.4
2022-12-29T14:20:42.503+0100	66.34	69.76	116.79	27.42	3202	23	512	68.4
2022-12-29T14:20:42.832+0100	66.61	69.76	116.66	28.99	3382	21	512	67.17
2022-12-29T14:20:43.334+0100	66.46	69.76	118.56	20.08	2381	34	512	67.17
2022-12-29T14:20:43.865+0100	66.49	69.76	116.43	28.73	3345	29	512	66.24
2022-12-29T14:20:44.317+0100	65.2	69.76	116.86	27.73	3241	26	0	66.24
2022-12-29T14:20:44.790+0100	65.41	69.76	117.68	24.17	2844	18	0	66.24
2022-12-29T14:20:45.375+0100	65.04	69.76	117.5	24.39	2866	26	0	65.65
2022-12-29T14:20:45.809+0100	64.6	69.76	116.77	28.06	3277	27	0	64.16
2022-12-29T14:20:46.252+0100	64.8	69.76	118.71	19.14	2272	27	0	64.16
2022-12-29T14:20:46.730+0100	63.9	69.76	119.11	16.83	2005	24	0	64.16
2022-12-29T14:20:47.220+0100	63.74	69.76	118.21	20.46	2419	29	0	62.97
2022-12-29T14:20:47.666+0100	62.98	69.76	118.52	20.59	2440	31	0	62.97
2022-12-29T14:20:48.145+0100	63.12	69.76	118.68	20.1	2385	31	0	62.29
2022-12-29T14:20:48.648+0100	62.89	69.76	117.25	27.31	3202	28	0	62.29
2022-12-29T14:20:49.183+0100	62.55	69.76	118.73	19.03	2259	31	0	63.48
2022-12-29T14:20:49.616+0100	62.01	69.76	116.88	27.33	3194	34	0	63.48
2022-12-29T14:20:50.299+0100	62	69.76	117.64	24.85	2923	27	0	62.74
2022-12-29T14:20:50.730+0100	62.74	69.76	116.71	28.84	3366	19	0	62.74
2022-12-29T14:20:51.122+0100	63.63	69.76	115.73	33.41	3867	14	256	64.42
2022-12-29T14:20:51.605+0100	64.17	69.76	116.53	30.22	3522	19	0	64.42
2022-12-29T14:20:52.062+0100	64.43	69.76	117.18	26.59	3116	23	0	65.01
2022-12-29T14:20:52.556+0100	64.74	69.76	116.23	28.41	3302	28	0	65.01
2022-12-29T14:20:52.971+0100	65.03	69.76	116.68	28.26	3297	20	0	65.51
2022-12-29T14:20:53.521+0100	64.8	69.76	116.46	28.66	3338	29	0	65.51
2022-12-29T14:20:53.957+0100	65.41	69.76	116.49	29.09	3389	23	0	65.01
2022-12-29T14:20:54.685+0100	64.98	69.76	115.07	34.48	3968	28	0	65.01
2022-12-29T14:20:55.004+0100	66.19	69.76	115.96	32.66	3787	17	512	66.99
2022-12-29T14:20:55.407+0100	66.53	69.76	115.68	32.2	3725	22	512	66.99
2022-12-29T14:20:56.122+0100	66.59	69.76	115.13	34.64	3988	19	512	67.6
2022-12-29T14:20:56.670+0100	66.65	69.76	115.67	31.39	3631	17	512	67.6
2022-12-29T14:20:57.000+0100	66.72	69.76	116.55	28.17	3283	21	512	67.42
2022-12-29T14:20:57.389+0100	66.95	69.76	118.1	20.74	2449	26	512	67.42
2022-12-29T14:20:57.801+0100	67.14	69.76	118.56	18.6	2205	26	512	67.42
2022-12-29T14:20:58.327+0100	66.1	69.76	118.06	21.51	2539	26	512	66.71
2022-12-29T14:20:58.820+0100	65.26	69.76	118.75	18.42	2187	32	0	66.71
2022-12-29T14:20:59.257+0100	64.16	69.76	119.5	13.79	1648	32	0	65.28
2022-12-29T14:20:59.743+0100	63.78	69.76	118.96	17.4	2070	31	0	65.28
2022-12-29T14:21:00.256+0100	61.81	69.76	119.75	14.39	1723	30	0	63.61
2022-12-29T14:21:00.721+0100	60.92	69.76	119.71	14.06	1683	37	0	63.61
2022-12-29T14:21:01.213+0100	59.38	69.76	118.66	18.71	2220	37	0	61.46
2022-12-29T14:21:01.721+0100	61.12	69.76	120.8	6.35	767	39	0	61.46
2022-12-29T14:21:02.188+0100	57.65	69.76	121.48	3.4	413	40	0	59.13
2022-12-29T14:21:02.700+0100	56.21	69.76	121.43	3.38	410	45	0	59.13
2022-12-29T14:21:03.101+0100	55.34	69.76	121.78	2.16	263	47	0	55.9

 

• 2nd log snippet with crash, no alarms being triggered here because nothing was hitting a threshold:

datetime

speed

speed_max

voltage

current

power

safety_margin

alarm

gps_speed

 

2022-12-29T14:23:16.538+0100	47.56	69.76	115.11	38.3	4409	31	0	57.4
2022-12-29T14:23:16.572+0100	49.9	69.76	114	41.05	4680	31	0	57.4
2022-12-29T14:23:16.599+0100	49.9	69.76	114	41.05	4680	31	0	57.4
2022-12-29T14:23:16.676+0100	52.34	69.76	111.62	50.18	5601	28	0	57.4
2022-12-29T14:23:16.724+0100	54.87	69.76	112.93	46.09	5205	23	0	57.4
2022-12-29T14:23:16.772+0100	59.3	69.76	113.89	40.87	4655	22	0	65.74
2022-12-29T14:23:16.785+0100	59.3	69.76	113.89	40.87	4655	22	0	65.74
2022-12-29T14:23:17.017+0100	63.38	69.76	109.25	60.07	6563	20	0	65.74
2022-12-29T14:23:17.033+0100	63.38	69.76	109.25	60.07	6563	20	0	65.74
2022-12-29T14:23:17.063+0100	63.25	69.76	110.28	56.69	6252	16	0	65.74
2022-12-29T14:23:17.116+0100	61.29	69.76	120.12	9.25	1111	100	0	65.74
2022-12-29T14:23:17.419+0100	59.4	69.76	121.81	0.71	86	100	0	65.74
2022-12-29T14:23:17.954+0100	47.48	69.76	122.06	0.01	1	100	0	57.83
2022-12-29T14:23:18.353+0100	40.28	69.76	122.18	0	0	100	0	57.83
2022-12-29T14:23:18.822+0100	31.83	69.76	122.25	0	0	100	0	41.27
2022-12-29T14:23:19.330+0100	25.39	69.76	122.32	0	0	100	0	41.27
2022-12-29T14:23:19.812+0100	21.19	69.76	122.39	0	0	100	0	21.97
2022-12-29T14:23:20.297+0100	17.15	69.76	122.43	0	0	100	0	21.97
2022-12-29T14:23:20.785+0100	12.93	69.76	122.45	0	0	100	0	21.97
2022-12-29T14:23:21.377+0100	9.49	69.76	122.5	0	0	100	0	4.31
2022-12-29T14:23:21.752+0100	8.3	69.76	122.53	0	0	100	0	4.31
2022-12-29T14:23:22.249+0100	7.88	69.76	122.57	0	0	100	0	0
2022-12-29T14:23:22.728+0100	5.56	69.76	122.6	0	0	100	0	0
2022-12-29T14:23:23.233+0100	3.26	69.76	122.63	0	0	100	0	1.81
2022-12-29T14:23:23.658+0100	1.16	69.76	122.64	0	0	100	0	1.81
2022-12-29T14:23:24.143+0100	0.1	69.76	122.68	0	0	100	0	0
2022-12-29T14:23:24.635+0100	0	69.76	122.68	0	0	100	0	0

 

Changes I will be doing to my EUC World alarms:

I will increase safety margin to somewhere around 18-20%, I still don't want false positive when doing non-aggressive riding, as I wrote before difficult to find the sweet spot here to match the wheel alerts and tiltback.

I will add a current alert for 50A current, looking at past logs it seems unusual to even go above 40A, 50A current alarm would have triggered in this situation.

And most important don't do hard acceleration at these high speeds.

 

 

Tagging analytic people who might be interested in reading this or want to analyze it:

@Chriull @supercurio @mrelwood

[Robse]

Gear done good job     Seems that 60 Amps is absolute max for that wheel.

[Rawnei]

21 minutes ago, Robse said:

Gear done good job     Seems that 60 Amps is absolute max for that wheel.

Yes it's a possible factor, but also interesting to know what 60A in EUC World means in practice, perhaps one has to look at BMS logs from the wheel directly to draw conclusions, but better if KS did analysis since they have all the facts.

[Punxatawneyjoe]

Very happy to hear you are ok, gear seems to make a huge difference in a crash situation and i don't wear enough of it. I will be getting a bunch more before getting the v13. Thanks for the info on EUC world and the gear you were using.

[Scoo]

Sad to hear that you crash but thank you for sharing so we can learn!

One thing come to me directly that I wonder is why it cut out. Especially when EUC world calculate 16% safety margin and that you have been below 16% before.

54 minutes ago, Rawnei said:

 

Voltage per cell was 3.6V, amp was 15 A/cell at cut out. The cells should be able to handle more Amps.

My options:

1. Voltage dip to 109 volt reduced the top speed of the wheel so you get closer to max speed which could reduce the max power the motor can give. From my understanding these motors get reduced torque/power at end of powerband. One earlier datapoint show that 15% was reached at 113 volt, 67,58 km/h and 25,73 amp.

2. Motor controller could have max current limit to 60A and then cut power. This i think is very dangerous for an EUC.

3. EUC world collection point missed the highest load due to being so quick that it cut. Not likely due to it has one more point after max before cut out.

4. Bump in the road made something happen lock

[Rawnei]

3 minutes ago, Scoo said:

2. Motor controller could have max current limit to 60A and then cut power. This i think is very dangerous for an EUC.

3. EUC world collection point missed the highest load due to being so quick that it cut. Not likely due to it has one more point after max before cut out.

4. Bump in the road made something happen lock

2. This could be the case, also why I now set 50A current alarm.

3. Sample rate could also be too low thus not sending data fast enough.

4. No bumps, this was our local "highway" relatively new pavement on a long flat straight.

[Bizra6ot]

Imo +20A in 300ms seems high for it to be just an overpower by accelerating while you were already launched, wouldn't it be cumulated with a hole or bump?
For the 60A it could be that KS has set this limit as the one at standstill since the S20 in NYC

[meepmeepmayer]

1 hour ago, Rawnei said:

...but also none of my safety mechanisms alerted me of what was about to happen, it's possible that wheel was beeping but I can't hear wheel beeps over the wind wearing a helmet which I think is the usual situation for most riders, I could feel no tilt-back from the wheel, none of my EUC World alarms that I have configured was triggered (I checked the logs and will detail more on this below), I usually rely on EUC World and respect those alarms.

There is simply no time for any safety mechanism to kick in. A sudden strong acceleration that overleans you (which you pretty much only can do near the top speed, which you did) is going to happen too fast for any beep to sound or tiltback to kick in. You might very well have been a bit below the speed beeps, and then accelerated and that was too much.

Four  solutions for this problem (in general) I can think of:

• (Bad) Make wheels warn like 20kph earlier than they now do, to have a bigger safety margin for accelerations at speed. Then the S22 would be a 50kph max wheel
• (Best) Make wheels so absurdly fast that nobody would ever go that fast (is that possible?) and there you have your safety margin!
• (Good) Maybe high discharge cells can fix this issue! If you have less voltage drop just from the acceleration, you will have more time for warnings I guess.
• (Reality) Just don't accelerate hard if you are ~20kph or less close to the usual beeping top speed of the wheel.

[Chriull]

Here are both of your log snippets in a speed vs current diagram. Don't know how high the "lift cut off speed" for the S22 is and how full your battery was. Just assumed 112 km/h as max no load speed in your situation?

So this would lead to the red "overlean limit" line and the "light blue" 15% safety limit line.

The overlean limit line could be steeper, as the only recorded sample once you fell still had 16% safety limit and you were still accelerating.

8 minutes ago, Rawnei said:

3. Sample rate could also be too low thus not sending data fast enough.

Your phone seems to have a bad bluetooth connection with the wheel and/or seems overburdened by EUC World? Or the S22 sends data as it likes?

You have up to 0.9 seconds lapsed between some data points! Minimum 0.013 seconds with an average of 0,4 seconds.

Not really anything usable or to rely on for alarms.

The second log (green line) with your fall just took ~0,5 seconds from the first recorded point at the left until 5 data points further you overleaned. Here sample time was excellent...

But with too high safety margin values compared to the first (blue) graph...

11 minutes ago, Rawnei said:

2. This could be the case, also why I now set 50A current alarm.

As one sees from the graph current alarm alone is not usefull - below 40 km/h 50A battery current are absolutely no problem...

1 hour ago, Rawnei said:

I could feel no tiltback at all, overall the tiltback on the S22 is very weak and difficult to feel and I consider it not a very good safety function to rely on due to this, my point of reference for a great tiltback implementation is the Begode Custom FW by @Freestyler which feels very safe and responsive in comparison to the one on the S22.

Yes - a fixed speed tiltback offers no safety for overleans. @Freestylers pwm tiltback FW is a much better protection. But still you would have just some tenth of seconds to react from the tiltback startinig to overlean.

Especially as you released the burden a bit before you accelerated "fully" into tiltback. So there is about no way for any protective measure to help you in such very special situation

 

1 hour ago, Rawnei said:

Enable speed limit alarm with 0kmh margin, I have set my speed limit to 66kmh on the S22 which will trigger this alarm, this is dynamic and will match any speed throttling done by the wheel I think 

The speed throttling is, afair logged in euc world and you should see in every line of the log the actual tiltback speed (max speed throttled by the firmware). Could be nice to compare this in your logs - as written above you had a very unlucky situation with burden decrease just before Kingsongs and EUC Worlds alarm threshold and then too fast of an acceleration... A perfect way to trick the safety mechanisms.

1 hour ago, Rawnei said:

Changes I will be doing to my EUC World alarms:

I will increase safety margin to somewhere around 18-20%, I still don't want false positive when doing non-aggressive riding, as I wrote before difficult to find the sweet spot here to match the wheel alerts and tiltback.

Seeing the insecurities in reported values from the S22 and the time delays this will still not catch all cases. You'll have to learn the wheel's limits. And/or wait for pwm tiltbacks for KS wheels...

Which is somehow already implemented by the dynamic max speed - will be interesting how the limits changed in your case. Imho the limit is a bit too high - afair it was at 88% PWM with the KS16S...

1 hour ago, Rawnei said:

I will add a current alert for 50A current, looking at past logs it seems unusual to even go above 40A, 50A current alarm would have triggered in this situation.

Battery current is unfortionately a bad measure for wheels burden. Just at 100% PWM it is equal to motor current - before it's "very off"

1 hour ago, Rawnei said:

And most important don't do hard acceleration at these high speeds.

+100!

[Ben Kim]

You failed to mention one key piece of information: ambient temperature. 
 

I did some digging which indicates you live in Sweden; it appears you don’t exactly have warm temperatures out there, so your overlean cutout is due to the batteries not being able to deliver the current requested due to colder operating temperature. 

 

rule of thumb: hard accelerate 7-10 kph less in colder temps (under 5C) than you would in warmer temps. I learned this the hard way as a new rider myself. Glad you’re okay though! 

Edited December 30, 2022 by Ben Kim

[Rawnei]

1 hour ago, Ben Kim said:

You failed to mention one key piece of information: ambient temperature. 
 

I did some digging which indicates you live in Sweden; it appears you don’t exactly have warm temperatures out there, so your overlean cutout is due to the batteries not being able to deliver the current requested due to colder operating temperature. 

 

rule of thumb: hard accelerate 7-10 kph less in colder temps (under 5C) than you would in warmer temps. I learned this the hard way as a new rider myself. Glad you’re okay though! 

Yesterday wasn't so cold maybe around 10c and this was also not long after leaving home so I doubt ambient temperature was a big factor.

[Rawnei]

2 hours ago, meepmeepmayer said:

There is simply no time for any safety mechanism to kick in. A sudden strong acceleration that overleans you (which you pretty much only can do near the top speed, which you did) is going to happen too fast for any beep to sound or tiltback to kick in. You might very well have been a bit below the speed beeps, and then accelerated and that was too much.

Sure it can if it's PWM based and have decent enough margin 🙂 speed based tiltback is a very blunt and not effective enough safety mechanism.

[Rawnei]

2 hours ago, Chriull said:

Here are both of your log snippets in a speed vs current diagram. Don't know how high the "lift cut off speed" for the S22 is and how full your battery was. Just assumed 112 km/h as max no load speed in your situation?

So this would lead to the red "overlean limit" line and the "light blue" 15% safety limit line.

The overlean limit line could be steeper, as the only recorded sample once you fell still had 16% safety limit and you were still accelerating.

According to this chart, shouldn't 15% safety margin be reached around 40A and raise an alarm?

[novazeus]

i learned at 18, one guy tooling around on a dirt bike is safe. add another kid on a dirt bike now u got a race and somebody is gonna die.

might be a stupid question, what is "vibration" in the king song app now? i don't think my old king songs had vibration. is that what they are calling tiltback now?

anyway, yesterday i was kinda timing myself how long it took to get all bundled up in protection gear. it's a skillset. 

i was thinking about the euc races, and i thought a race to see who could get dressed in their protective gear the quickest, and then get inmotion to sponsor the event and see which rider survives a 55mph crash the best. 

i just unlocked the speed on my s18, which for me, wasn't even necessary because i'll probably never go 20 mph on it. but it does have like 4 warning tiltback settings in the king song app. does everybody not use the king song app. i know darknessbot is popular, but idk why it's necessary?

and ps, anybody shave down that stupid center rib on the horrible tire on the s18. i guess king song wanted everyone to feel what a 2.125" tire feels like. if the tire patch was round, it wouldn't be a problem. this particular tire definitely needs to be run at lower pressures. not speed wobbles, just falling to one side of the rib. it tries to wobble all the time. super annoying. worse tire ever in 7 different eucs i've owned. i get on the s22 with its normal tire profile and it's like, thank u Lord.

if u get a new s22 from jason and he's putting s18 tire on them for the street tire, u will die. that tire with it's pronounced cent.er rib wasn't made for a one wheel device. i mean duh!

look at the left side of my tire.

 

[Tawpie]

2 hours ago, novazeus said:

might be a stupid question, what is "vibration" in the king song app now?

I think it makes your phone vibrate when an alarm goes off, but I use EUCW when riding so don't know for sure

[Funky]

Maybe phone was in vibrate mode - sound turned off, or at very low volume. EUCWorld makes no alarms, if sound is turned off, or is at very low volume.. (Don't ask me how i found that out.)  At least for my it was the case - because of sound came true bluetooth connection. (speaker/music thingy..)

Still there should have been the original Kingsong alarms+pedal tilting. (Ofc if user haven't turned them off. Or set them at max-max speed that app allows..)

 

EUCWorld also makes phone vibrate - when alarm goes off.

Simply ride slower or get "faster" wheel.. I'm riding my wheel at ~80% and almost never go over that amount. (Yeah i have left 15-20% to more safety.. As i never ride "max" speed.) Hitting 70 km/h often. I for sure would not go faster than 65 km/h EVER! If wheels max speed is 70 km/h.. (Even all built-in safety..) I simply would add extra 5-10km/h safety.

If one is riding at very close to max speed - quick acceleration is a NO-NO!!!

Edited December 30, 2022 by Funky

[KiwiMark]

If I don't understand this correctly can someone more knowledgeable correct me.

I have found tilt-back on my RS works really well, I set a speed and if I go much above that I can feel the wheel tilting me back.  But if you over-lean and the wheel doesn't have enough power to match your lean and therefore cannot balance you, surely it does not have enough power to tilt you back either.  So, as you approach too high a speed the tilt-back is an effective tool, but for over-lean it can't help you?

Louder upward facing speakers that are set to give maximum volume alert when the power output exceeds 80% or 90% or whatever, may help.  But if you lean hard to gain maximum acceleration then you may go from fine to over-lean before you can react to any beeps.  There probably isn't any fool proof way that wheel can prevent every crash that could ever happen, if you aren't going to ride super conservatively then at least wear decent gear so you reduce the chances of getting hurt.  Even when manufacturers try to build in a greater safety margin, the riders are soon asking "would there be a way of updating the firmware to increase the limits?", I've seen this question asked for the V13 where riders are not happy to be limited to 80kph or 90kph, they want to hit crazy fast speeds and just hope that they won't actually exceed the limits of what the wheel can do - cause, you know, what is the worst that can happen?

So far I don't think I've exceeded 15kph below my maximum top speed on my RS, when I bought it I decided on the high speed version so that I could ride decently fast and still have a fairly large safety margin.  But, after passing 1,000km I have felt more confident in my riding and my speeds have gone up from what they used to be.  I can't really say how fast I'd feel confident riding on a Sherman S with good suspension helping me to not feel nervous about hitting bumps.

[level9]

11 minutes ago, KiwiMark said:

I have found tilt-back on my RS works really well, I set a speed and if I go much above that I can feel the wheel tilting me back.  But if you over-lean and the wheel doesn't have enough power to match your lean and therefore cannot balance you, surely it does not have enough power to tilt you back either.  So, as you approach too high a speed the tilt-back is an effective tool, but for over-lean it can't help you?

Correct. tilt-back requires more power (the wheel must speed up) in order to work. So an aggressive overlean typically means immediate face-plant due to insufficient power.

Something I always try and keep in mind when riding a wheel near the top speed - only use minor inputs on acceleration when near the limits.

[chanman]

Yep you hit the trifecta there, 1. Hard acceleration 2. Near top speed 3. Lower on battery charge. Glad you and the wheel weren't badly damaged.

Actually maybe not all that low battery, voltage sag made it look low but I see now 122V at rest so mostly charged. Just curious if your wheel has 40T or 50E cells?

Tiltback won't always kick in if there's no more power available, and beeps can be delayed, too quiet, or at the same time as the overlean occurs.

I do find it problematic that safety margin was reported to still be above 15%, meaning the controller should have been able to give more PWM, so maybe there's something to 60A being a hard current limit being enforced. 

Edited December 30, 2022 by chanman

[Rawnei]

There are couple of factors that can make tiltback reliable:

It needs to be noticeable and not too weak but also not too strong, you need to feel and understand that it's happening and it also needs to be responsive to go back down as you ease off, the back and forth responsiveness is an important feedback to the rider.

Tiltback needs to rely on wheel power output and have a decent enough margin, speed based tiltback is not great as there are many more factors than speed that determines power output of the wheel.

19 minutes ago, chanman said:

Yep you hit the trifecta there, 1. Hard acceleration 2. Near top speed 3. Lower on battery charge. Glad you and the wheel weren't badly damaged.

Actually maybe not all that low battery, voltage sag made it look low but I see now 122V at rest so mostly charged. Just curious if your wheel has 40T or 50E cells?

Tiltback won't always kick in if there's no more power available, and beeps can be delayed, too quiet, or at the same time as the overlean occurs.

I do find it problematic that safety margin was reported to still be above 15%, meaning the controller should have been able to give more PWM, so maybe there's something to 60A being a hard current limit being enforced. 

Almost full battery, 92%, stock KS cells.

Tiltback on S22 is not reliable, it's too weak i.e. hard to feel and it's also speed based.

[redfoxdude]

Oh man, this gives me flashbacks to my overlean on a 16X a few years ago. I'm glad to hear you are alright. 

1 minute ago, Rawnei said:

Tiltback on S22 is not reliable, it's too weak i.e. hard to feel and it's also speed based.

I really hope they will significantly improve this. If they moved it to PWM threshold and implemented a similar tiltback to Begode's in conjunction with Freestyler's custom FW, that would be pretty ideal. I've tended to quite like Begode's tiltback, it's smooth and not jarring, but can absolutely make it harder to pass a given speed. I recall accidentally having it set to 28mph on my 100V Nikola when I still had it, and it was genuinely difficult to push past. I'd love to see this on more wheels - it would be a major step towards safer EUCs for all of us.

[Rawnei]

53 minutes ago, redfoxdude said:

Oh man, this gives me flashbacks to my overlean on a 16X a few years ago. I'm glad to hear you are alright. 

I really hope they will significantly improve this. If they moved it to PWM threshold and implemented a similar tiltback to Begode's in conjunction with Freestyler's custom FW, that would be pretty ideal. I've tended to quite like Begode's tiltback, it's smooth and not jarring, but can absolutely make it harder to pass a given speed. I recall accidentally having it set to 28mph on my 100V Nikola when I still had it, and it was genuinely difficult to push past. I'd love to see this on more wheels - it would be a major step towards safer EUCs for all of us.

Yeah I think it should be the standard all manufactures should strive for.

[Chriull]

18 hours ago, Rawnei said:

According to this chart, shouldn't 15% safety margin be reached around 40A and raise an alarm?

Sorry for posting this chart with not more detailed comments - it's made with, i assume the from the s22 reported _battery_ curent - which is "wrong". As i wrote battery current equals motor current at overlean (pwm = 100%) below motor current is higher than battery current.

Motor current is proportional to torque, battery current is just some more or less "unrelated value" the lower pwm% get.

Also the lift cut off speed value of 112 is just any guess - no idea which soc your wheel had and how much the lift cut off speed is at all for the s22.

The upper right point, about were your accident happened still reported a safety margin of 16% - so pwm reporting, averaging or whatever is somehow off with the s22 phone combination you have or just another point is missing with lower safety margin were you really overleaned. So the red line should be somewhere steeper and starting from some "real lift cut off speed" which will shift the blue line accordingly.

Battery current is no value to base an alarm which can protect from an overlean. As some fixed speed is not. One can restrict oneself with high safety margins with some combined alarm...

Additionally the overlean limit changes with battery charge state.

Imho changing to soime 18-20% safety margin should be better.

Make such scatter charts of your graph showing you points with 0-5%, 5-10%, 10-15%, 15-20%, ... ranges of safety margin and decide from this what could work?

But then again - the pwm ranges are "very intermixed" in the higher burden parts... Maybe they make more sense with more data?

[Chriull]

BTW: here an old graph from https://forum.electricunicycle.org/topic/7855-anatomy-of-an-overlean/?do=findComment&comment=307699 i made trying to extrapolate the overlean limit from battery current vs speed with the pwm values:

As one sees the overlean limit from the reported values is more a range than a limit...

 

[Student4Life]

Thanks Rawnei and everyone who shared!  I was looking for what a shoulder joint support harness would protect, but it was really great to see what Rawnei's gear protected.  His shoulder pad saved him from road rash but not joint trauma, and the skid plate seems to have been adequate joint protection.

I've had one cut-out, it was a hard acceleration from a dead stop at an intersection so I don't understand why the spec sheets focus so much on speed, I can see everyone here understands it's about rider over-lean which is about system (battery, motor, controller) over-current.  My understanding is that the Battery Management Controller is prioritizing the battery and wiring and motor at the expense of rider safety and I sure wish new battery management / control circuits would fail with a reduced-but-not-zero power output mode.