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1000 km., MSX Review...

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8 minutes ago, Meelosh123 said:

I can't get over how it affects quick turns left and right when carving, slaloming, and just swishing around.  The hard mode feels much more in control and exact when doing those actions.

Hmmm.... I don't feel this at all; hard mode has less nuanced control, I can't ride it anymore if I have the option of Gotway soft mode.

Do you utilize your heels and toes while maneuvering on soft mode? (ie. heels up and toes up on opposing feet)

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I can see there is room for debate on the wattage of motors in EUC's. If the motor wattage given by a manufacturer cannot be believed that may be for another conversation. I understand the measurement of watts in an EUC motor to roughly translate into power. In comparing an MSX to a Monster and to an MCM5 I am only making the point that most buyers/riders would prefer that the larger the wheel, the more watts (power) they prefer. If two different sized wheels have the same exact motor (same watts/power), than the larger wheel with the same motor will not perform as well as the smaller wheel using the same motor. I referred to this concept as watts per inch (size of tire), not a measure of distance travelled.

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3 hours ago, Mrd777 said:

Try to give soft mode a couple of days to really adjust to the sway of the pedals. I ride with about 3 degrees of backwards lean. I’m not sure how you ride with an 8 degree forward lean, as that might be screwing up your perspective on riding soft. The monster 100volt preforms beautifully in soft mode.. 

Thanks, I think I will. I find the forward tilt comfortable and agile. It also allows for heavy, sit-down-style, pendulum braking on the trailing edge of the pedal. I've found technique is crucial on the MSX under heavy braking to avoid death wobbles. It's not the most balanced wheel on the planet and carries its weight pretty high. One of my concerns about the Nikola is how high its weight seems to be... I might have to ask about that over in the Nikola thread. :) 

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9 hours ago, Michael Tucker said:

I can see there is room for debate on the wattage of motors in EUC's. If the motor wattage given by a manufacturer cannot be believed that may be for another conversation. I understand the measurement of watts in an EUC motor to roughly translate into power. In comparing an MSX to a Monster and to an MCM5 I am only making the point that most buyers/riders would prefer that the larger the wheel, the more watts (power) they prefer. If two different sized wheels have the same exact motor (same watts/power), than the larger wheel with the same motor will not perform as well as the smaller wheel using the same motor. I referred to this concept as watts per inch (size of tire), not a measure of distance travelled.

I can understand your reasoning behind this approach - seems sound and it feels compelling to "follow".

I just tried again, to follow this the physical/mathematical way. Mechanical Power is defined as

P(ower in Watt) = M(torque in Nm) * omega(radiant per second in rad/s).

M = F(orce in N) * r (radius in m), v (speed of the EUC in m/s) = 2 * r * pi * omega / ( 2 * pi) = r * omega, omega = v/ r .

So P = F * r * v / r = F * v  (pfff... tataaaa ... the definition of power for translation.....)

So to overcome some force F (wind resistance, friction, incline and/or acceleration) at a given speed v a certain Power P is needed - regardless of the wheel diameter! A 2000W motor will behave exactly the same - no matter if on a 14, 16, 18 or 20 inch wheel! So the felt, experienced and reported  differences must have some other origin/reason.

With a 2000W motor at 10 km/h (=2.8 m/s) one could reach a force of 2000/2.8 = 720 N. Thats enough to accelerate 100 kg with 7.2 m/s².

At higher speeds - for example 40 km/h this would lead to a "available" force of 180N, accelerating 100 kg by 1,8 m/s². But about ~70N are already needed to overcome air drag and friction, so "just" 110N stay available for acceleration.

The interesting point here is, that this power at 10 km/h is never available in real life - a wheel with a lift cut off speed ~80 km/h and 84V battery would need to deliver a motor current of 190A to reach this 2000W power output. That would vaporize the mosfets and cables quite instantly - so the current limiting is already active.

Maybe as wheels with smaller diameter reach lower (lift cut off) max speeds (?do they really?) they'd have higher back emv at lower speed and so lower motor currents (low speed high torque motor) and by this they reach higher accelerations at lower speeds with less motor current? Is that maybe the reason for the higher "performance" of smaller wheels? Because they are not so acceleration limited by the needed current limit?

 

Edited by Chriull
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4 hours ago, Chriull said:

wheels with smaller diameter reach lower (lift cut off) max speeds (?do they really?)

The same motor installed on a smaller rim already delivers smaller max speed, so generally yes.

 

4 hours ago, Chriull said:

Is that maybe the reason for the higher "performance" of smaller wheels? Because they are not so acceleration limited by the needed current limit?

The word ”performance” should be defined to be able answer. But every time the difference has been bought up, it has been about how effortless the acceleration is on a smaller wheel. Not a hard acceleration where current limiting might occur, but the difference that exists already when accelerating very peacefully. For example at 1/10 of the reported maximum nominal power handling.

The reason for the difference is that a larger wheel requires a greater CoG shift to create the same amount of imbalance which the wheel will then try to remedy. For the same lean a large wheel stays upright with a smaller distance travelled, and the contact point on a large wheel is also longer.

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6 hours ago, Chriull said:

So the felt, experienced and reported  differences must have some other origin/reason.

You feel a difference in oomph (the best definition on "performance" I can give, quick acceleration and braking) when accelerating or decelerating, not when going at constant speed. You feel no difference at constant speed. So one needs to look at acceleration, not any constant speed.

If you can come up with some nice lines of math that explain why smaller diameter wheels have more oomph or torque (at least in the layman's sense how they feel, maybe not mathematically/physically), as is obviously the case looking at reality, that would make me very happy:) I'm afraid some second order stuff (derivatives) must appear, and while I haven't tried yet, as a non-physicist not sure that would go so well.

6 hours ago, Chriull said:

- a wheel with a lift cut off speed ~80 km/h and 84V battery would need to deliver a motor current of 190A to reach this 2000W power output. That would vaporize the mosfets and cables quite instantly - so the current limiting is already active.

2000W/84V = 23.8A (100% battery) and 2000W/66V = 30.3A (0% battery on Gotways, 3.3V per cell) and 2000W/60A = 33.3A (0% on KS18XL, 3V per cell). So anything under 35A is in the nominal area of a "2000W motor", and the motor can take much more the shorter the high current (high power) appears. And the batteries can give much more current.

Not sure how you get 190A:)

Again, let's not confuse power (as in: the actual power delivered by the batteries and used at any point in time to keep the wheel balancing, the power requirement) and nominal motor power (the highest continuous power the motor can do without overheating*, a very imprecise number, handwaved by the motor supplier). Motor power (nominal and max) are more or less meaningless numbers in this context unless they're an order of magnitude different to typical actual power numbers (they're not).

(*This is actually what nominal motor power means, right?)

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7 minutes ago, meepmeepmayer said:

You feel a difference in oomph (the best definition on "performance" I can give, quick acceleration and braking) when accelerating or decelerating, not when going at constant speed. You feel no difference at constant speed. So one needs to look at acceleration, not any constant speed.

This is the maximum power and acceleration available being available from (at) any "constant" speed. So the possible umpf one can get at the given speed. 

7 minutes ago, meepmeepmayer said:

If you can come up with some nice lines of math that explain why smaller diameter wheels have more oomph or torque (at least in the layman's sense how they feel, maybe not mathematically/physically), as is obviously the case looking at reality, that would make me very happy:) I'm afraid some second order stuff (derivatives) must appear, and while I haven't tried yet, as a non-physicist not sure that would go so well.

Everything already here/answered: :D

2 hours ago, mrelwood said:

The reason for the difference is that a larger wheel requires a greater CoG shift to create the same amount of imbalance which the wheel will then try to remedy. For the same lean a large wheel stays upright with a smaller distance travelled, and the contact point on a large wheel is also longer.

All 2000W motors regardless of wheel diameter are able to perform the same oomph (i like this "definition" :) ) it's just "easier" to achieve on smaller wheels.

And as written in my post above - smaller wheels with less lift cut off speed can provide more oomph without getting into the current limit...

 

7 minutes ago, meepmeepmayer said:

2000W/84V = 23.8A (100% battery) and 2000W/66V = 30.3A (0% battery on Gotways, 3.3V per cell) and 2000W/60A = 33.3A (0% on KS18XL, 3V per cell). So anything under 35A is in the nominal area of a "2000W motor", and the motor can take much more the shorter the high current (high power) appears. And the batteries can give much more current.

Not sure how you get 190A:)

Sorry i skipped to show this step in detail in my post.

At  lift cut off speed a wheels motor produces a back emv equal to the battery voltage. If this lift cut of speed is 80 km/h, the battery voltage 84V then the motor produces at 10 km/h a back emv of 84V / 80 km/h * 10 km/h = 10.5V. So the electrical power put in is this back emv times motor current. This equals the 2000W mechanical output power - so the motor current in this example is 2000/10.5 = 190A.

 

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17 hours ago, houseofjob said:

Hmmm.... I don't feel this at all; hard mode has less nuanced control, I can't ride it anymore if I have the option of Gotway soft mode.

Do you utilize your heels and toes while maneuvering on soft mode? (ie. heels up and toes up on opposing feet)

Unless I'm on a very straight and boring multi-use path, my feet are constantly shifting and moving, not sure what they're doing at this point :lol:

On soft mode, when zig-zagging, I inevitably put weight forward and backwards as well, so the spongy soft action/dip comes into effect.  For me, I couldn't get used to that tiny bit of lag when it comes to quick little turns.

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6 minutes ago, Meelosh123 said:

Unless I'm on a very straight and boring multi-use path, my feet are constantly shifting and moving, not sure what they're doing at this point :lol:

On soft mode, when zig-zagging, I inevitably put weight forward and backwards as well, so the spongy soft action/dip comes into effect.  For me, I couldn't get used to that tiny bit of lag when it comes to quick little turns.

Ah, I see.

I like the lag because I tend to load up all my weight for each push, plus it emphasizes the upper torso moving a step ahead of the lower legs.

But to each their own!

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I also love soft mode , love the feeling, love the sway and it's just a smoother nicer ride for me 😊

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I started this riding season on the MSX soft mode, but as I started riding more aggressively, I had to go back to medium mode for two reasons.

1) The MSX soft mode is still rock hard for fast movements. It only tilts if you keep the lean for at least a second. This gives a nice natural curve to medium acceleration and braking. But during fast braking it feels as if the wheel is slowly running out from under me, or losing grip. Also the tilt gets severe enough that my ankles struggle with keeping the weight on my heels. I feel like I’m falling on my back.

2) When the tire slips even slightly on a steep bumpy off-road hill, the riding position changes suddenly, and the wheel will start to make up for it quite slowly. So the riding angle changes uncontrollably. I need to feel precisely if I’m losing the grip, and the soft mode often makes me think that’s the case.

The new MSX 2 has been said to have 30% ”better” acceleration and 50% ”better” braking, whatever that means. I would be extremely interested to try the different modes on the MSX 2, as it might indeed be a huge improvement.

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Ive always rode on hardest, but after these conversations I tried soft :blink1:, It dips so so much I thought I was gonna fall off and when cornering Im afraid to touch the ground as I generally turn my body into a corner. So far its been very good on hard, I do like how responsive the wheel is, but gonna give it a shot on Med...

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