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[TheRan]

Anyone know whether the max speed limit (not in the app, what the bike is limited to with the custom setting maxed out) is based off the speedo reading or the motor RPM?

What I'm wondering is if changing the gearing (for example fitting the chain kit) and having the dealer modify the software so the speedo reading is correct lowers the max speed or if it remains the same. Obviously the motor can only spin so fast so changing the gearing too much would lower the max speed no matter what, so assume the motor can spin fast enough to reach the same top speed with the lower gearing.

Also, when getting the software adjusted do you think a dealer would be willing to input values different to what the chain kit comes with, say if you wanted to gear it even lower?

[Auriga]

I can't tell you much about the app, but I can tell you the typical chain kit gearing lowers the top speed. Lowering the gearing further would further lower the top speed. The motor rpm is limited somewhere between 5-6krpm(I think) and you get pretty vclose with the rated max speed Zero gives with a belt.

In short, there isn't really any RPM wiggle room to lower gearing while maintaining top speed

[Gains]

The motor rpm is limited to protect the rotor ( centifugal forces ).
If you change the gearing, you will change top speed.
This explains the difference in top speed between SR and S for example.

[TheRan]

So what about the European bikes that are limited to 86mph, where as the American ones are limited to 98mph with the same gearing? By my calculations that would mean the Euro bikes are limited to about 5800rpm and the American bikes go all the way to 6700rpm. So, if the speed limit is based on the speedo reading then a Euro bike should be able to maintain the same 86mph top speed with a front sprocket swap from 18t to 16t. If it's RPM based then the top speed drops to about 75mph.

[Auriga]

So what about the European bikes that are limited to 86mph, where as the American ones are limited to 98mph with the same gearing? By my calculations that would mean the Euro bikes are limited to about 5800rpm and the American bikes go all the way to 6700rpm. So, if the speed limit is based on the speedo reading then a Euro bike should be able to maintain the same 86mph top speed with a front sprocket swap from 18t to 16t. If it's RPM based then the top speed drops to about 75mph.

I don't think those are geared differently, I think the regulations for the EU and US surrounding what can be advertised as top speed are different.

Gains is right, there is a hard rpm limit to protect the motor, and the bike calculates speed based on pulley sizes, wheel size and motor rpm. Changing any of those should allow you to change top speed and/or torque, but motor rpm will limit top speed, since there isn't really any extra headroom before the limit.

[TheRan]

So what about the European bikes that are limited to 86mph, where as the American ones are limited to 98mph with the same gearing? By my calculations that would mean the Euro bikes are limited to about 5800rpm and the American bikes go all the way to 6700rpm. So, if the speed limit is based on the speedo reading then a Euro bike should be able to maintain the same 86mph top speed with a front sprocket swap from 18t to 16t. If it's RPM based then the top speed drops to about 75mph.

I don't think those are geared differently, I think the regulations for the EU and US surrounding what can be advertised as top speed are different.

Gains is right, there is a hard rpm limit to protect the motor, and the bike calculates speed based on pulley sizes, wheel size and motor rpm. Changing any of those should allow you to change top speed and/or torque, but motor rpm will limit top speed, since there isn't really any extra headroom before the limit.

That's what I'm saying, they're geared the same but the American bikes can achieve a higher top speed (and thus higher motor RPM). So, if the limit is determined by the speedo then the Euro bike can just spin the motor faster (up to whatever the American bikes can do) to achieve the same top speed with lower gearing.

What I'm trying to determine is whether the max speed limit = motor rpm*pulley size*tyre size (i.e. the speed displayed by the speedometer) or whether it is just the maximum motor rpm and Zero just converts that to whatever speed it results in with stock gearing and assumes no-one will change it.

I have a feeling it may be determined by the speedo reading judging it based off the FX and FXS. Both are limited to 85mph. If they both had the same max motor RPM then the FX should actually be able to do almost 88mph. Of course they could have the max motor RPM set lower for the FX so this is just assuming they're the same which would be the simplest method.

[Auriga]

Let me try and be clear. I think the gearing and software for the American and EU versions of the bike are identical. What Zero lists as top speed in their marketing materials is probably different due to differing regulations surrounding advertising and vehicle claims in the two countries.

I have a feeling it may be determined by the speedo reading judging it based off the FX and FXS. Both are limited to 85mph. If they both had the same max motor RPM then the FX should actually be able to do almost 88mph. Of course they could have the max motor RPM set lower for the FX so this is just assuming they're the same which would be the simplest method.

I know Zero calculates bike speed to display on the dash based on pulley sizes, wheel size and motor rpm, from settings configured on the mbb. This is why people who install chain kits or larger/smaller tires have inaccurate speedometers.

I think you're forgetting tire sizes. FX and FXS have different size tires, which would lead to different top speeds assuming the same gearing and max motor rpm.

Max speed the bike can obtain is at max motor rpm.

[TheRan]

It's not, it's the actual top speed of the bike (my EU bike will only hit 86mph and I'm sure one of you Americans can confirm your's will get to 98mph). I think the reason for the lower top speed is due to how the continuous power output is calculated (which allows them to sell it as an 11kW bike for the European A1 class), it being measured at a certain percentage of the max speed. For the R model bikes that don't need to fit into the A1 class the top speed is the same whether it's an American or a Euro bike.

[Crissa]

Well, don't Zeros get mph from counting the motor rpms?

-Crissa

[Auriga]

Was your bike sold as a 11kw bike? All I know about those is continuous power is limited to 11kw. I don't know how that calculation is performed, but I imagine that could easily limit top speed.

We don't really see many of those in the US, but I have seen one imported from the EU.

Well, don't Zeros get mph from counting the motor rpms?

-Crissa

Yes, but you have to consider tire sizes and gear ratio to calculate mph. Those are set in the MBB.

[TheRan]

Well, don't Zeros get mph from counting the motor rpms?

-Crissa

Yes, but I'm not sure if the top speed limit in the spec sheet is based on the speedo reading or the motor RPM.

Was your bike sold as a 11kw bike? All I know about those is continuous power is limited to 11kw. I don't know how that calculation is performed, but I imagine that could easily limit top speed.

We don't really see many of those in the US, but I have seen one imported from the EU.

It is an 11kW bike. The 11kW continuous power output is based on how much power it takes to maintain a certain speed and I think that speed is a percentage of the max speed, thus lowering the max speed lowers the continuous power output. There's not actually any power limiting and it doesn't take full power to maintain the top speed. Other than the top speed, which is an artificial limit, they have performance identical to American spec bikes and so should be able to reach the same 98mph should the software limit be removed.

[Gains]

In Europe ,we have drivers licenses for 125 cc motorcycles with a max power of 11kw.
Zero has some models (S DS FX FXS ) with software that limits the performance of the motor to fit the regulations for those licences, so people that don t have the full drivers licence can ride a zero. There is also an other limit of 35kw in some european countries .
The idea is that motorcyclists can t start on a powermonster without experience but have to learn step by step .

[Fifty3]

I don't believe it is limited by the speedometer.  I just rode my '16 FXS to an "indicated" 90 MPH, at which point, it shut down and coasted to a stop.  I'm not convinced it was going that fast.  My town has a radar speed check set up to inform drivers of their speed as they drive by.  The radar speed shows 29 MPH while my Zero speedometer shows 34 MPH.  If that discrepancy is correct, my actual speed would have been 77 MPH when the speedometer indicated 90 MPH

[TheRan]

It should, or rather can be, very accurate as it uses the RPM of the motor and some math to figure out the speed and it knows quite accurately how fast the motors is spinning. The only way it should be able to be inaccurate is if the math is off. There are three ways that could happen, you've changed the gearing without changing it in the software, the gearing in the software has been changed, or you've fitted a different size tyre.

The fact that your bike can get up to an indicated 90mph (on flat ground?) and I assume the limit is supposed to be 85mph like current FXS models (I wouldn't have thought they'd lower it) indicates that the limit is motor RPM based.

[Gains]

On the 2013 models it is the MBB that limits the speed ,it receives the rpm of the motor from the contoller.
I think the dashboard receives this info via the MBB
When you change gearing ,you have to change the setting on the dashboard to get a correct speed reading again.
I replaced my MBB ,and the bike now goes to 123 km/h in eco while it should be limitted to 113 km/h  (70 mi/h ) and it does indicate 123 on the dashboard.