Is ks18l top speed really 50kph?

[joku]

I've been using digihud on my phone to track my speed, and it seems to match car speedometers. Tonight i was testing my speeds and digihud said my max was 40.76 while the kingsong app says 44.72. I don't think the ks18l can truly go 50kmh. What do you guys think? I'm riding with the tire at 38psi

[Rob Valley]

measuring speed with either GPS or the unicycle itself is like trying to measure inches with your thumb. 

 

[joku]

I get what you're saying, but I use the same GPS app in the same phone to test speeds on several esk8s and cars and all those speeds correlate to exactly what's being shown on the app - the ks18l doesn't. Anyways, it's max speed is not 50kmh and probably something closer to the ninebot z10(if the advertised speed is correct)

[Rob Valley]

what i would like to see is more measurments using laser, ie. speedguns, this would give some answers and not guesses

[joku]

I have a tachometer. I can test the rpm without load. I understand why you guys would disregard the GPS test even though that's been tested against 3 cars and 4 eboards and all speeds match the measurement. Ultimately, I already know the max speed of the 18l is below what's advertised, but I'm looking for other people who have tested it too 

Edited August 19, 2018 by joku

[Rob Valley]

i would say that the problem with GPS measurements is relativity, wich they compensate for, the same way you could say the wheel compensates to convert to a speed reading from a tacho meter, so there is a lot of "head room" for errors, now when we are down to measure speed by +/- 1 Km/h accuracy , oh no sorry, tenth of a kilometer, like you posted.

either way, to have a accurate measuring device, like a calibrated speed gun, would be the best, for the discussion, overall

[joku]

2.5mph off difference so far. Unfortunately I don't have a speed gun

[Lutalo]

4 hours ago, joku said:

Ultimately, I already know the max speed of the 18l is below what's advertised

How do you know this? I don't have a gun, but I have my third alarm set at 49kph and I deactivated it twice earlier today on some speed runs. I know speed is reduced somewhat aggressively when battery levels drop. Can the alarms go off early with a full charge?

[joku]

3 hours ago, Lutalo said:

How do you know this? I don't have a gun, but I have my third alarm set at 49kph and I deactivated it twice earlier today on some speed runs. I know speed is reduced somewhat aggressively when battery levels drop. Can the alarms go off early with a full charge?

The wheel is calculating 49kph, but it's not really 49kph and probably closer to 45kph.

Edited August 20, 2018 by joku

[Lutalo]

4 minutes ago, joku said:

The wheel is calculating 49kph, but it's not really 49kph and probably closer to 45kph.

???? I think this conversation is best served by the most accurate device possible to measure speed.

[joku]

Sure.  For most of us 46kph is more than fast enough, but don't be surprised if a z10 can keep up with you or maybe even pass you :p

[cbgti]

With a low pressure of 2.3bars in the tire (smaller diameter), I have a gap about 6% between the GPS Speed and the speed shown in the app.

[baracuda50]

I didn't see any video that ks18 l reaches 50km/h after 200 unlock?

Have you seen one of them?

[Jerome]

Interesting. My KS18L is unlocked, but it never occurred to me that it wouldn't reach 50 kmh as advertised. I don't need 50 kmh speed, but it is somewhat disappointing if KS deliberately lied. Unless I find someone with a calibrated speed gun, I will never know.

[Rob Valley]

i dont think it is such a big deal, the 50 km/h is a theoretical max of power, that the wheel can output, if the limit would be say, 70, you could cruise along all nice and dandy and record your 50. but since it is the limit of power, all kinds of factors come in, how wide you are, the road, your psi etc. 

GPS is a positioning system, not a speed meter, tacho meters are measurments of two or more points on a rotating axis, not a speed meter.

a laser measures the difference between two beams, and since, it is based on a fixed constant, the speed of light, is the most accurate tool to measure velocities. 

Edited August 20, 2018 by Rob Valley

[US69]

On 8/20/2018 at 5:10 AM, joku said:

Sure.  For most of us 46kph is more than fast enough, but don't be surprised if a z10 can keep up with you or maybe even pass you :p 

Did you ever get the idea that perhaps a Z10 or whatever brand Wheel isnt that highly exact in measuring Speed, too? The best example may be my Monster which is off by up to 20% regarding the Speed shown by the apps…….

On 8/19/2018 at 9:13 AM, joku said:

I've been using digihud on my phone to track my speed, and it seems to match car speedometers. Tonight i was testing my speeds and digihud said my max was 40.76 while the kingsong app says 44.72. I don't think the ks18l can truly go 50kmh. What do you guys think? I'm riding with the tire at 38psi

Perhaps you try it with some higher psi Setting...Speed measured by apps only depends on revolutions of the wheels...The real kmh which can be done with that Rotation highly depends on tire radius, tire brand, state, pressure, so also riders weight etc etc....

17 hours ago, Jerome said:

but it is somewhat disappointing if KS deliberately lied.

And thats how rumours get to Facts........ :-) 

I can absolutly promise that "KS did not deliberately lie"!!! 

Edited August 21, 2018 by US69

[Nils]

On 8/19/2018 at 9:13 AM, joku said:

I've been using digihud on my phone to track my speed, and it seems to match car speedometers. Tonight i was testing my speeds and digihud said my max was 40.76 while the kingsong app says 44.72. I don't think the ks18l can truly go 50kmh. What do you guys think? I'm riding with the tire at 38psi

Not that car speedometers are not really accurate as far as I know, they're typically designed to never show speeds lower than your actual speed (and are required by law to do this in the UK for instance). This  means they employ a safety margin which means the reading from the car's speedometer will normally be higher than your actual speed. This is more noticeable at higher speeds than lower, but given this it seems somewhat strange that digihud would correspond well with your car. In the US the regulations are somewhat different so perhaps your car doesn't do this, but for European brand or I'd expect this to be the same regardless of the target market.

[Lutalo]

2 hours ago, Jerome said:

but it is somewhat disappointing if KS deliberately lied

Why on God's spinning blue ball would they "deliberately" lie over a few kph difference?

Children lie about stealing cookies because they don't like upsetting Mommy, A girlfriend might lie about her whereabouts and who she's with to avoid exposing her true nature and/or intentions with you. A student might lie about why a homework project is incomplete to avoid getting a bad mark, employees might lie to their supervisors when they need a day off to avoid being fired or written-up, etc. If one is going to lie, all the above scenarios represent good reasons to do so. But Kingsong lying about a speed capability....?????. 

It is already widely known that speed and range varies according to the rider, terrain, and environmental characteristics.

Perhaps all manufacturers overstate speed capability. If overstating speed is an industry norm then there is probably a good reason aside from deliberately trying to hoodwink the customers upon whom they depend for their survival; many of whom are enthusiasts that tend to instrumentally confirm the real world performance parameters of the machines after purchase.

Edited August 20, 2018 by Lutalo

[Jerome]

10 hours ago, US69 said:

Did you ever get the idea that perhaps a Z10 or whatever brand Wheel isnt that highly exact in measuring Speed, too? The best example may be my Monster which is off by up to 20% regarding the Speed shown by the apps…….

Perhaps you try it with some higher psi Setting...Speed measured by apps only depends on revolutions of the wheels...The real kmh which can be done with that Rotation highly depends on tire radius, tire brand, state, pressure, so also riders weight etc etc....

And thats how rumours get to Facts........ :-) 

I can absolutly promise that "KS did not deliberately lied"!!! 

Bingo! I have seen this feeding frenzy happen before on the forum. I am embarrassed to have participated even a little bit. My KS18L is unlocked and fast. I am sure under some conditions it will hit 50 kmh for sure. It may do it with me on it or not. That has nothing to do with KS credibility.  US69 I am sure you had no idea that you were signing up for all this. The KS18L is a superb machine in bill quality and performance. It was toss-up between the Z10 and the KS18L and I made the right choice for me.

[joku]

Yes I've considered that the Z10 might not have advertised or even tested true speed. I never said it would be faster than the KS18L. I just said don't be surprised if it is. The speed measurement displaying on the kingsong app has very little(possibly some) to do with my weight - I'll eat 2 whole pizzas to prove it.

Edited August 21, 2018 by joku

[squirt]

55 minutes ago, joku said:

Yes I've considered that the Z10 might not have advertised or even tested true speed. I never said it would be faster than the KS18L. I just said don't be surprised if it is. The speed measurement displaying on the kingsong app has very little(possibly some) to do with my weight - I'll eat 2 whole pizzas to prove it.

I would suspect, though, that your weight in combination with tire pressure would have an effect on a GPS app that measures speed based on time and distance, instead of revolutions of a wheel...  I believe with a heavier weight and a lower tire pressure, the effective diameter of the tire would be less, which means you would travel less per revolution, which would make the kingsong app indicate one speed and a GPS app indicate another.  I try to keep my wheels at a higher pressure to account for that.

[US69]

6 hours ago, Jerome said:

US69 I am sure you had no idea that you were signing up for all this. T

That brings it on point....sometimes I am really speechless about some of the assumptions and/or false information flattering around on social media :-)

For the announced speed...I find it much more questionable when a brand promotes and announces a wheel for example at 40kmh...and in truth the wheel can only do that speed on 95-100% battery and then at 60% battery already got down 32-34kmh....Is that a 40kmh wheel? 

 

[mrelwood]

18 hours ago, Rob Valley said:

the 50 km/h is a theoretical max of power, that the wheel can output

It’s not. The top sustainable riding speed is limited by the firmware on all other than Gotways. On the 18L the limit is set at 50km/h (40 for the first 200km). The free lift speed shows the theoretical maximum, and it will likely be closer to 70 even with the 18L.

[joku]

1 hour ago, mrelwood said:

It’s not. The top sustainable riding speed is limited by the firmware on all other than Gotways. On the 18L the limit is set at 50km/h (40 for the first 200km). The free lift speed shows the theoretical maximum, and it will likely be closer to 70 even with the 18L.

Free lift speed doesn't show the theoretical max wheel speed. It just shows what the firmware is willing to do without load or high amperage. The speed on a BLDC motor is a function of the voltage & duty cycle of the pulse width modulation which is controlled by the firmware

Edited August 21, 2018 by joku

[mrelwood]

11 minutes ago, joku said:

Free lift speed doesn't show the theoretical max wheel speed. It just shows what the firmware is willing to do without load or high amperage. The speed on a BLDC motor is a function of the voltage & duty cycle of the pulse width modulation which is controlled by the firmware

I consider them to be the same thing. Theoretical max speed of a separated motor itself is of course a different thing, I think ”a wheel” is considered to include the firmware (and tire, shell etc, everything that makes it an EUC the vehicle).

But I think we are now entering semantics of an unnecessarily precision. The point was that 50km/h is not a theoretical maximum power output on the 18L, but a predetermined, firmware limited top speed.