Kingsong S20/S22 (Confirmed)

[Forwardnbak]

1 minute ago, Marc Roberts said:

Seems most people are reporting it being easy to overpower at low speeds, and Adam’s pedal dipping going up stairs is bothering me. This might be the only thing that concerns me so far.

Yes I agree with that. I was holding on with all the issues staying really positive. But the dip was very disappointing. 
Also lack of testers willing to do speed tests says something is off to me. 

[Rawnei]

31 minutes ago, Marc Roberts said:

Seems most people are reporting it being easy to overpower at low speeds, and Adam’s pedal dipping going up stairs is bothering me. This might be the only thing that concerns me so far.

Yes I agree, that's the most concerning thing, wonder what technically causes the dip, maybe it has some relation to the ramp up time in fw going from standstill? Hopefully it's something that can be further tuned in software I can't imagine why it would be a hardware issue.

[EMA]

On 3/5/2022 at 1:52 AM, Tawpie said:

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

 

On 3/5/2022 at 2:49 AM, supercurio said:

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?

yes, the higher position decrease the leverage of the rider, simply that 

[EMA]

13 hours ago, Seba said:

While it's not recommended to do this regularly (in general it's best not to deeply discharge the battery), 18XL is fully safe to do so when needed (for example when you're on long-distance ride). Here's the last year ride, during which I fully discharged battery several kilometers before my planned end of the tour. To get into a place where my hotel was located I had to restart the wheel several times to get out of low battery tiltback, then final kilometers were ridden in tiltback (battery was fully discharged so restarting the wheel helped only for just few seconds) - https://euc.world/tour/599513067607328. When riding last kilometers I just watched voltage to avoid dropping it substantially below 60 V (3.0 V per cell). The lowest voltage recorded was 58,9 V, what translates into 2,94 V per cell. A value absolutely safe for battery, as every cell can be discharged down to 2,5 V according to the specs. Apparently, you can't do this on S20. Actually, one should avoid riding S20 when battery voltage drops to 99 V.

remember also 18xl has a super thin street tire which is probably around 1.2kg (cst 1488 is 1.3kg) and s20 has a beefy rim with a 50/50 tire

[Eucner]

Thanks for welcoming reminder of riding basics.

1 hour ago, mrelwood said:

The rider’s CoG vector is vertical only when stationary, and when there’s no wind. When accelerating, the vector points a bit backwards.

The CoG vector is always toward to mass center of the Earth. The sum vector with wind resistance and other forces could point differently.

1 hour ago, mrelwood said:

But I think what’s more important here is the the distance from the pedals to the axle, ie pedal height, since it’s the lever we use to tilt the wheel. When braking, the force of our weight trying to continue forward is applied below the axle, which tilts the wheel backwards. If the pedals are close to the axle, the lever is short and the force is small.

The high pedals will just raise the riders CoG and create a bigger moment against the braking moment.

[Eucner]

41 minutes ago, EMA said:

s20 has a beefy rim with a 50/50 tire

That's really thin and low profile tire .

[Seba]

1 hour ago, EMA said:

remember also 18xl has a super thin street tire which is probably around 1.2kg (cst 1488 is 1.3kg) and s20 has a beefy rim with a 50/50 tire

Yes, I know. S20 tire is also wider and the rolling resistance is higher due to knobby tread. Still, I hoped for little more range from a 2200 Wh battery.

[techyiam]

4 hours ago, mrelwood said:

The rider’s CoG vector is vertical only when stationary, and when there’s no wind. When accelerating, the vector points a bit backwards. For the rider to be able to stay standing on the pedals, the vector (+wind) must pass through the pedals, otherwise the rider falls.

But I think what’s more important here is the the distance from the pedals to the axle, ie pedal height, since it’s the lever we use to tilt the wheel. When braking, the force of our weight trying to continue forward is applied below the axle, which tilts the wheel backwards. If the pedals are close to the axle, the lever is short and the force is small.

The force due to mass being acted on by earth's gravitational field is commonly known as weight. The direction of gravity is always radial if you are observing from outer space, or vertical if you are on earth's surface. Therefore, the direction of the force due to the weight will always be vertical.

Torque equation:    τ = r x F

Or in simpler term in our case, torque is equal to the force multiplied by the component of the positional vector that is perpendicular to the force vector (moment arm).

Since weight always acts in the vertical direction, the moment arm will always be the horizontal component.

For acceleration, if the pedals are mounted above axle height, the moment arm can increase in length. If the pedals are mounted below the axle height, the moment arm can decrease in length. In fact, the lower, the shorter.

However, in practice, the forward tilt is not insignificant enough to really make a serious difference in torque.

Edited March 6, 2022 by techyiam

[Paul A]

Is the S20 better than the other suspension wheels?

[OldFartRides]

It’s different. Next year at this time we will know much more.

Edited March 6, 2022 by OldFartRides

[techyiam]

2 hours ago, Eucner said:

The high pedals will just raise the riders CoG and create a bigger moment against the braking moment.

That plus, the best braking techniques seem to involve some form of sitting, which is utilizing the length of our body to move the CofG more rearward than higher, anyways. Which makes sense when one thinks about it. In fact, that's what EVX used.

Which leads us to the conclusion that we can't really blame the S20's high pedal height for its weak braking performance perceived by some. 

 

Edited March 6, 2022 by techyiam

[Rawnei]

15 hours ago, Rolzi said:

 

So, Adam took his V11 to that same hill today and it completely burned out at the same spot that the S20 was struggling. 😅

https://www.instagram.com/tv/CawyLD_FE8D/

[OldFartRides]

Funny, someone commented “ most biased YouTuber ever..”

I asked biased how, exactly ?

I like his vids. 

[fryman]

Due to the top heaviness, do you think s20 uses more power to balance? A test may prove this to be true.

[Eucner]

2 hours ago, techyiam said:

That plus, the best braking techniques seem to involve some form of sitting, which is utilizing the length of our body to move the CofG more rearward than higher, anyways.

That plus, the more rearward to CoG is moved, the more likely it is to get braking wobbles.

[Miko.cz]

Its interesting how Adam is OK with breaking, but not so fine with suspension. A bit rare opinions I think.

[meepmeepmayer]

7 hours ago, Marc Roberts said:

Adam’s pedal dipping going up stairs

A thought about that:

Older wheels (Gotways certainly) had a consistent forward dipping if you rode over something that rapidly and regularly shook the wheel, like going over a cattle grid. "Brrrrrrrr" and the sensor apparently couldn't deal with this kind of fast, regular vibration, and the pedals skewed forwards more and more until they reset when you were off the grate. (Not sure about newer wheels.)

The going up stairs in the video comes close to this kind of vibration.

So I'm not 100% sure the pedal dipping there was due to overpowering the wheel. It might just be this "cattle grate phenomenon".

But probably 90% sure it was still just overpowering, which would mean lackluster firmware or power delivery. Just wanted to mention the other possibility.

[mrelwood]

25 minutes ago, meepmeepmayer said:

So I'm not 100% sure the pedal dipping there was due to overpowering the wheel. It might just be this "cattle grate phenomenon".

The cattle grate phenomenon that In familiar with happens rather slow though, and developes over a time period of several seconds. The way Adam made the wheel dip looked like the tire simply got stuck in one of the stairs and dipped right away.

 I’d say it was 100% an overlean, ie. insufficient power for the demanded task. Just like what happened at the steep sandy hill.

[UniVehje]

Cancelled. I think going with 4p was a mistake. 

[Seba]

4 minutes ago, mrelwood said:

The cattle grate phenomenon that In familiar with happens rather slow though, and developes over a time period of several seconds. The way Adam made the wheel dip looked like the tire simply got stuck in one of the stairs and dipped right away.

 I’d say it was 100% an overlean, ie. insufficient power for the demanded task. Just like what happened at the steep sandy hill.

Today we had a S20 demo day in Gdansk and some folks that tried this wheel, experienced this short lack of torque when trying to accelerate a bit more aggressively. Just now I updated this wheel from 2.14 firmware to 2.15, as its descripton says "curr overload time longer". While KS firmware descriptions are somewhat cryptic and written in Chinglish, it may suggest that 2.14 was too conservative and King Song relaxed overcurrent detection thresholds. But this is just a speculation.

[Seba]

3 minutes ago, UniVehje said:

Cancelled. I think going with 4p was a mistake. 

Definitely it's not a wheel for long distance riding, especially when you're going for a multi-day trip.

[meepmeepmayer]

31 minutes ago, UniVehje said:

Cancelled. I think going with 4p was a mistake. 

I wouldn't blame 4p, other 4p wheels have been fine. For example, havs anybody overpowered the RS or Nik 1800Wh at low speed?

It's just weird power delivery by KS.

[fbhb]

9 minutes ago, meepmeepmayer said:

I wouldn't blame 4p, other 4p wheels have been fine. For example, havs anybody overpowered the RS or Nik 1800Wh at low speed?

It's just weird power delivery by KS.

Agree with the weird power delivery statement, but it also needs to be remembered that the S20 is still currently pre-production. Along with the fact that even at this stage King Song have Already put out 2 firmware updates and 2 BMS updates.

So who knows, given time they may manage to get the firmware dialled in further to address some of the power delivery concerns, King Song tend to work away on multiple firmware releases historically!

Edited March 6, 2022 by fbhb

[Paul A]

Maybe the pedal dip/insufficient power is due to:

the first three meters power limit to protect mosfets thing?

[Seba]

All right... Yesterday I did a range test that ended up yielding a lot of interesting conclusions, but also ended up destroying my jacket, pants, gloves and hip bag . I regret the gloves the most, because they were a gift from my lovely wife, but the pants and jacket were my favourite Marmot Precip's that accompanied me during all my long-distance, multi-day trips...  Today I organized a demonstration meeting, which was attended by many riders and thanks to which we managed to gain more conclusions and experiences. Now it's time to work on improving the support for S20 in the EUC World app. And this time the experience with S20 is only positive, because I managed to introduce into application support for smart BMS in this wheel