Kingsong S20/S22 (Confirmed)

[RagingGrandpa]

23 hours ago, supercurio said:

Or 12x Hunteck HGB039N15M? In TO-263 package, in parallel.

Tho I'm not sure if 150V would be considered enough voltage margin for a 126V wheel.

TO-263 is surface-mount, which is very difficult for heatsinking. It would be new territory for an EUC.

Instead, I bet it's still through-hole TO-247, screwed to a heatsink.

I heard a rumor of IRF150P220, which is 3x the cost of Hooyi (+$100 per EUC) but otherwise logical... hope a teardown gets us real information soon.

[Tawpie]

29 minutes ago, Forwardnbak said:

I just wondered if the bad brake result might come from a power limit on the board similar to the first 3mtr thing but reverse? 

The amount of braking is controlled by hardware and software, and the system can be expected to limit the amount of braking in order to keep the electronics from failing. So if the braking is bad, it's because either the hardware isn't up to it or because the firmware is being too cautious. (that got me thinking... the V12 was faulted for lackluster braking—were they protecting the MOSFETs?)

But I'd be surprised if it was related to the 3 meter thing—I'm guessing the 3 meter thing is due to torque limiting when the wheel isn't turning, either because of a switch to senserless or because they don't want to blow up the MOSFETs when they're driving a near stalled motor (more power demanded than they want to deliver)

Edited March 4, 2022 by Tawpie

[fbhb]

17 minutes ago, RagingGrandpa said:

TO-263 is surface-mount, which is very difficult for heatsinking. It would be new territory for an EUC.

Instead, I bet it's still through-hole TO-247, screwed to a heatsink.

@RagingGrandpa, I have posted this information from the S20 website previously confirming TO-247 are used, but adding it again here in light of the current discussion:

 

Edited March 4, 2022 by fbhb

[supercurio]

After chatting today with someone who has been riding a S20 for some time now, I have some observations which should explain a few comments from people who tried a S20 also:

1/ Geometry (EDIT: might be wrong, would need confirmation)

It's one of the wheel which has the highest pedals.
The higher the pedals, the further forward or backwards the rider will need to lean, in order to move the center of gravity relative to the contact patch.
You will find that pads which restricts too much how one can lean forward for instance will give the impression that the wheel lacks torque and is difficult to accelerate or slow down.

Light riders might find it even harder to accelerate since the suspension will have less sag. However shorter riders might be used to lean far already so that might not be too surprising for them.
Very hard suspension settings, taking more time to sag when stepping on the wheel, will also give a feeling that acceleration is limited in the beginning, since the rider will initiate it from a higher pedals position.

On flat ground, geometry is the most significant aspect determining how easy it will feel to accelerate or not.
(when climbing, wheel diameter increase in importance)

2/ Foot placement on the pedals

Something that came up in a discussion was the feeling like the back of the wheel is heavier, a sluggish acceleration (but no problem to brake) and some foot pain. It typically indicates that this tester would have his feet offset towards the rear of the pedals, which automatically favors easy braking, requires more effort to accelerate and to carry more weight on the front of the feet during most of the riding.

Feet being offset front or back on the pedals is directly a consequence of power pad & foot lock placement. S20 stock pads for instance are kept back in their positioning due to the "boomrang" guides.

Conversely, if you hear from someone that braking was difficult (an outlier) it probably means that his/her feet were likely offset to the front in order to favor ease of acceleration - possibly to compensate for pads design which don't allow to lean forward sufficiently.

3/ Pedal mode

It looks like most are testing the wheel in hard mode, which keeps the pedals very flat on Kingsong wheels, including in turns.
Without assistance to lean forward and backwards, many riders will find difficult to move their center of gravity that much ahead or back, especially if the pads installed limit their range of motion.

We know that some wheels have pedal dipping in turns. In case it's not purely accidental due to bad sensor fusion data correction (on some buggy firmwares), I believe that the main goal is to facilitate acceleration out of turns. A wheel which doesn't have might feel not as easy to accelerate.

4/ Power Pads setup

For acceleration, the ability to transfer the center of center of gravity forward is key to an effortless access to torque (as well as foot placement)
For hard braking, same it's all about the shape, width and placement of the power pads.

The permanent adhesive on the S20 pads makes adjustments difficult, resulting in many riding with suboptimal pads setup, not tuned for their morphology or shoes.

 

TLDR: just the usual reminder that until it's over-powered, a wheel can accelerate or brake harder. But the ease to do so depend on these 4 parameters.
The S20 is an outlier in all 4 category because:

• it keeps the rider higher up (EDIT: might be wrong, see 1/)
• comes with difficult to adjust footlocks
• has one of the hardest pedal mode out here keeping the pedals always flat: no assistance to shifting the center of gravity
• power-pads design is limiting

Some riders like Adam (Wrong Way) and Ginger On Wheels reported to over-power the S20 already, but for many others, it'll be all about ease of access to the torque for the reasons developed.

My advice:

• make sure your power pad choice and placement allows you to move freely your center of gravity wherever you need it to be, and you are fully supported even in the extreme cases (aka no going around the pads to accelerate more, stuff like that)
• adjust the pedal height if necessary. (EDIT: might not have an effect, need confirmation)
• let the suspension sag sufficiently (by changing the coil if required) (EDIT: might not have an effect, need confirmation)

 

11 hours ago, RagingGrandpa said:

TO-263 is surface-mount, which is very difficult for heatsinking. It would be new territory for an EUC.
Instead, I bet it's still through-hole TO-247, screwed to a heatsink.

I heard a rumor of IRF150P220, which is 3x the cost of Hooyi (+$100 per EUC) but otherwise logical... hope a teardown gets us real information soon.

Oops, I mixed up TO-247 with TO-263. Thanks for pointing the error!
Yes the spec says TO-247 as @fbhb noted while I've been writing this 😂 .This IRF150P220 rumor gives something to check against, cool!
Let's ask people who have access to a S20 and are willing to look.

Edited March 5, 2022 by supercurio
note that point 1, on geometry might be wrong.

[Blunzn]

1 hour ago, Tawpie said:

... either because of a switch to senserless or ...

there is no switch. 

the S20 has a hall sensor cable 

and in the 2021 S20 Reveal video Kingsong stated ...

 

so as probably none of the hallsensors broke down till now, nobody really experienced how the hall-sensorless emergency mode feels.

 

 

[Tawpie]

41 minutes ago, supercurio said:

The higher the pedals, the further forward or backwards the rider will need to lean, in order to move the center of gravity relative to the contact patch.

My geometry is rusty, but I'm having a difficult time understanding this.

[Tawpie]

5 minutes ago, Blunzn said:

there is no switch.

My apologies, poor choice of words on my part. There's some thought that when you start out, you must use a conventional hall sensor so the system uses them during the first 2 meters. Once the wheel is moving and the senserless system is pretty sure which direction the wheel is moving, the speculation is that KS may 'switch' to controlling the motor using the sensorless control. This would be handled in firmware.

That is of course, speculation. We just don't know. Me, I'd just use the conventional hall sensors and keep the sensorless system in reserve in case a hall sensor breaks but I can easily see an argument for using sensorless as much as you can so that a broken hall sensor doesn't result in as bad of an accident. Especially since the speeds are much higher than KS has been comfortable with in the past.

[supercurio]

58 minutes ago, Tawpie said:

My geometry is rusty, but I'm having a difficult time understanding this.

A drawing would be better, but I agree the formulation I used wasn't the best, and writing it as "angle" probably would work better.

Maybe this extreme (unrealistic) exemple could help - let me know

Moving the rider's center of gravity situated at 1m of height, 1m forward: the angle between the contact patch and the center of gravity would be 45°, introducing a high amount of torque applied by the rider onto the wheel via pedals and power pads

Now, with really really high pedals: moving the rider's center of gravity, situated at 2m of height, 1m forward: the angle between the contact patch and the center of gravity would be 26.57°, resulting in a lower amount of torque applied onto the wheel despite the same amount of forward learn by the rider.

Therefore less acceleration from the wheel, which seems less responsive.

Does that check out?

Edited March 5, 2022 by supercurio

[Tawpie]

41 minutes ago, supercurio said:

Does that check out?

Not really... and yes, a drawing would be helpful. My problem is that the green triangle's dimensions stay the same, no matter how far above the ground you are (the lean angle doesn't change or you're trying harder/less). If the lean angle and the hypotenous don't change, the length of the adjacent and opposite sides of the triangle cannot change either.

THIS IS HARD MODE, where there is zero pedal dipping and the pedal stays directly above the contact patch.

 

When you have pedal dipping (soft mode), the dip will move your CG forward of the contact patch. With the same dip angle, your CG will move farther forward if you're higher off the ground so this seems backwards to what is described. Except the part where soft mode improves your ability to accelerate.

???

I get that when you're higher off the ground you might not want to lean at the same angle because your brain objects... maybe that's it?

Edited March 5, 2022 by Tawpie

[Tawpie]

oh wait. A very important part is the length of the lever between the pedal hanger and the axle of the wheel. Raising the pedals makes that lever shorter because the pedal hanger is closer to the axel and thus applies a lower tipping force to the wheel.

That makes sense now. It's the relationship between the point of force application and the rotational center of the wheel that matters. Yes, moving the CG further forward matters, but it's probably swamped by the reduction in the lever arm when applying the resulting force.

(for the record, I loathed statics and dynamics when I was in school, and this is why)

maybe... if, as the math people like to do, you take the distance from the pedal to the rotational center of the wheel to the limit (zero), then all of the force is trying to twist the wheel forward, none is spent trying to swing the pedal backwards and up. Help! I'm way out of my league here.

sorry, this is all nonsense, I have no idea what's actually happening. I think the lever we're actually worried about is the one that rotates around the contact patch—we're trying to tilt the wheel relative to the contact patch.

Edited March 5, 2022 by Tawpie
nothing to see here, clueless idiot rambling

[SanDiegoGuy]

So does geometry and physics indicate that a short and light weight rider would have a harder time riding the S20 because of the relatively higher ratio weight of the wheel compared to the rider as well as having less torque exerted on the wheel when leaning forward?

[techyiam]

Sorry, I am too lazy to search for yoos post which states: (I am paraphrasing)

Maximum torque exerted by the the rider on the wheel to accelerate is only dependent on the weight of the rider and the length of the pedal (specifically the distance measured from axle to the front edge of the pedal).

However, as the diameter of the wheel increases, the motor needs to produce more torque in order to accelerate at the same rate. Which means the rider needs to exert more torque on the wheel. And hence, on larger wheels, most rider use power pads. 

Moreover, a taller rider doesn't have to lean as much to move his center of gravity to the front edge of the pedal.

The rider's weight to euc weight ratio is not one of the primary factors that affects acceleration. However, from the maneuvering viewpoint, it is.

In conclusion, the short answer to your question is a yes.

Edited March 5, 2022 by techyiam

[.....]

2 hours ago, SanDiegoGuy said:

So does geometry and physics indicate that a short and light weight rider would have a harder time riding the S20 because of the relatively higher ratio weight of the wheel compared to the rider as well as having less torque exerted on the wheel when leaning forward?

thoeretically makes sense. In practice tho, theres a bit more to it than that. We also must assume that KS used a Chinese midget when setting up the algos for torque delivery. Just as most wheels werent designed with power pads in mind, and adding them makes it much easier to overlean. Perhaps the s20 was designed with a midget AND power pads in mind. If so, the FW makes worry of limited power from limited height, somewhat moot. IN the end tho, being tall > being short. No I aint biased, Im 6'3". Im also easily capable of overleaning ALL of my wheels with power pads, at a mere 130lbs.

Edited March 5, 2022 by ShanesPlanet

[techyiam]

41 minutes ago, ShanesPlanet said:

thoeretically makes sense. In practice tho, theres a bit more to it than that. We also must assume that KS used a Chinese midget when setting up the algos for torque delivery. Just as most wheels werent designed with power pads in mind, and adding them makes it much easier to overlean. Perhaps the s20 was designed with a midget AND power pads in mind. If so, the FW makes worry of limited power from limited height, somewhat moot. IN the end tho, being tall > being short. No I aint biased, Im 6'3". Im also easily capable of overleaning ALL of my wheels with power pads, at a mere 130lbs.

Look at what euc girl can do on her V11. And how she can ride her dad's monster pro, a wheel that is heavier than her. The talent, the courage.

[Seba]

6 hours ago, Tawpie said:

There's some thought that when you start out, you must use a conventional hall sensor so the system uses them during the first 2 meters. Once the wheel is moving and the senserless system is pretty sure which direction the wheel is moving, the speculation is that KS may 'switch' to controlling the motor using the sensorless control. This would be handled in firmware.

I think that Hall sensor is used all the time, and sensorless mode (back-EMF sensing) is used as a backup, in case of Hall-sensor failure.

[supercurio]

8 hours ago, Tawpie said:

Not really... and yes, a drawing would be helpful. My problem is that the green triangle's dimensions stay the same, no matter how far above the ground you are (the lean angle doesn't change or you're trying harder/less). If the lean angle and the hypotenous don't change, the length of the adjacent and opposite sides of the triangle cannot change either.

THIS IS HARD MODE, where there is zero pedal dipping and the pedal stays directly above the contact patch.

 

When you have pedal dipping (soft mode), the dip will move your CG forward of the contact patch. With the same dip angle, your CG will move farther forward if you're higher off the ground so this seems backwards to what is described. Except the part where soft mode improves your ability to accelerate.

???

I get that when you're higher off the ground you might not want to lean at the same angle because your brain objects... maybe that's it?

thanks for the peer review @Tawpie 

Agree the angle is lower, but the lever is higher so maybe the result is the same? Will have to look into it another day 😁

[supercurio]

8 hours ago, SanDiegoGuy said:

So does geometry and physics indicate that a short and light weight rider would have a harder time riding the S20 because of the relatively higher ratio weight of the wheel compared to the rider as well as having less torque exerted on the wheel when leaning forward?

Short yes, unless willing to lean forward more than a tall rider in order to move the center of gravity forward as much.
Light no, because the lighter a rider is the lower amount of power is required to accelerate.

Although clearly not impossible as demonstrated by kids riding big wheels, hard accelerating and hard breaking will be more difficult to achieve for light and short riders since the weight they can transfer is small compared to the weight of the wheel itself.

[Miko.cz]

Seba ride of KS-S20 now online https://euc.world/tour/607550710424222 (also visible in his signature). Go Seba, go!

[Paul A]

Outstanding slope climbing ability of S20 Eagle.

Mar 5, 2022

King Song International

3.52K subscribers

 

[fryman]

Do you think the wider hanger style effects handling.

 

 

[Curt8892]

72 km in 0c temp. Sounds good to me. 

[Miko.cz]

1 minute ago, Curt8892 said:

72 km in 0c temp. Sounds good to me. 

Exactly, waiting for a note about his brutto weight.
I think his ride and EUCWorld ride record gaved me better info than 75% of all "reviews". As I am not extreme raider.

[Planemo]

3 hours ago, Miko.cz said:

Seba ride of KS-S20 now online https://euc.world/tour/607550710424222 (also visible in his signature). Go Seba, go!

Jesus, is it right that the wheel is maintaining a temp only just above ambient??!!

[Planemo]

Ok so looks like 50 miles/80Km at 15mph and 0 degC. 

[Blunzn]

16 minutes ago, Planemo said:

Jesus, is it right that the wheel is maintaining a temp only just above ambient??!!

marty's overheat hill test was pretty great for a fanless system. strange that in most of the review videos its almost never mentioned ... maybe some pendulum tests comparing it to other wheels would be interesting too  

outsidetemp: 25°

1st stop: ShermanMax - 55°C , Hero - 53°C, S20 - 42°C

2nd stop: ShermanMax - 50°C,  Hero - 45°C,  S20 - 33°C

3rd stop:  ShermanMax - 55°C  , Hero - 50°C  , S20 - 45°C

after the last superstep part of Overheat Hill:  ShermanMax - 58°C , Hero - 57°C , S20 - 57°C

 

and you can switch the stock thermal pads against some modern overclocking ones

 

 

Edited March 5, 2022 by Blunzn