Maximizing Range for the Stark Varg

[Erwin P]

HP is also dictated by what the motor delivers. And by the gearing. HP is independent from the gearing of the motor.

Yes and no. The total amount of it is dictated by the motor. At what speed it happens is dictated by gearing.

For example an ICE with 6 gears and meets peak hp 6 times over the wheelspeed range. At say 15, 25, 45, 60, 80 and 90 km/h depending on the gear ratios per gear.
Same applies to different gearings (wich are actually just gears that you can't shift but have to swap sprockets for) on an E. The lower the gear the higher the horsepower at lower wheel speeds and the other way around.

 

[vic321]

And an Stark does not have any gearing. But delivers over the whole rpm band. With nearly konstant HP over the whole upper band. No need for switching gear and looking for the right rpm band. So no need to change gearing. As long as most riders dont even use the full 80HP, but chose to drive with 50HP-

 

[Johnny Depp]

The speedo uses gps, there's no pickup for a traditional gauge and I'm not sure why anyone would want one. I commute on the bike during the week and mostly run the BRP on the weekends.

I could run a smaller sprocket on the back and maybe pick up a few miles if I ran interstate at sustained speeds but that's not how I use the bike. I'm in and out of the throttle on tight backroads for the vast majority of my daily commute.

I did a 200 mile day on my 2t motard a few months back and by the end of the day I was wishing I had taken the truck.

IIRC the Stark uses a countershaft sensor for mpg? I really don't know for sure, but yeah GPS is best. You don't seem to have a range issue, but the rideability is enhanced with taller gearing anyway IMO. It's not just for Supermoto and freeways.

 

[Johnny Depp]

On this past Sunday I got 15 miles of slow mostly single track with some Enduro gnarly hills used about 35% battery. So I could comfortably get the same as @Johnny Depp in the slow gnarl.

I am mostly stock with my newer Varg. Some Acerbis parts and an AXP skid plate still running the Pirellies (with IRC heavy duty tubes) till they are worn out, they don't like the 8 psi...


View attachment 14695

Hopefully more people will report back as you did, we need to standardize the math so that we can say I got X mpbattery % today so that we can learn from the comparisons.

 

[Johnny Depp]

Just read the last post again

The HP per wheelspeed. That's what the car industry has been doing for over a century and it's actually what gearing does.

The horsepower curve is also not flat. It is an actual curve. Just look up that dyno i posted not that long ago.

Edit: Here it is:
View attachment 14700

The top ond is the 80hp, wich you can see collide with the 60 and 70hp near the end.

I'd love to see something more current, there have been several mapping changes and IIRC Bryan had problems with wheelspin and the 80hp setting not being unlocked?

 

[Johnny Depp]

And an Stark does not have any gearing. But delivers over the whole rpm band. With nearly konstant HP over the whole upper band. No need for switching gear and looking for the right rpm band. So no need to change gearing. As long as most riders dont even use the full 80HP, but chose to drive with 50HP-

The intent on this thead was to demonstrate range increases (or not) with super tall gearing and zero Regen. It also increases rideability, less abrupt response, less wheelspin and wheelies.

 

[Johnny Depp]

The phone app for Stark showed 12.63 miles using 35%, trail pace, but the GPS app showed 14.5 miles. It may be because of the gearing changes?

 

[Karinshi]

The phone app for Stark showed 12.63 miles using 35%, trail pace, but the GPS app showed 14.5 miles. It may be because of the gearing changes?

i think it can be that

 

[markhamr]

I found the 15 and even the 14 I didn’t have enough wheel speed in slower corners and it unloaded the rear easier coming out
Needs a few fixes mainly too much weight transfer well just too much weight

 

[Erwin P]

It's sad the adjustable power curve is behind the paywall. But that could fix that issue. You could then go up in torque for those corner speeds and leave the rest the same.

 

[markhamr]

I am thinking maybe a 2 speed
Would be the way to go

 

[Erwin P]

I am thinking maybe a 2 speed
Would be the way to go

I agree. And that could be be very crude if needed to keep it cheap. Just stacking 2 gears and a simple mechanism wouldn't widen the bike a lott nor add serious costs. A "quickshifter" doesn't need a clutch and quickshifting something as smooth as a E motor is easy to program.
And well i guess having to stand still would even cut it since you probably only use it for street connections.

Sure this will add weight, but for the Enduro this would be huge for the rides you have quick street sections and crawl Enduro.

 

[Calicarver]

15/42 gearing
Zero Regen (parking brake)
Power setting is a minor factor, I leave mine on 60 all the time, I control it with my wrist rather than a setting.

This week I did 29+ miles and finished with 48% battery, a mix of hard pack single track, a flat track, and 3 loose MX tracks over 3 hours with stops. This seems to have surprised some owners who don't get this kind of range. I'm a slow old guy, 68 and C speed.

The key is no wheelspin and lowering the engine revs. If I would have done this gearing mod just for the rideability (it was never bad) it would have been worth it. Obviously the range is a benefit. I don't even bring my generator anymore, and have never needed it.

With the most torque in any dirt bike ever (including a Maico 700) this thing can absolutely pull the gearing, and I feel like Stark has made a big mistake with stock gearing. A side benefit is moving the rear axle all the way back to improve the rear suspension and minimize wheelies. The throttle response is much less sensitive to little inputs and irregularities from trail chop, so it's less tiring and faster and more effective.

Flame on if you want, but you can try it yourself for under $100.View attachment 14656

How much do you weight?

 

[Johnny Depp]

How much do you weight?

220

 

[Calicarver]

220

I'm 225 naked and so far getting 30-38 spirited single track miles with stock EX gearing (12/48?) with 15-20 % battery left. Next year I will try some taller gearing to compare. Would love to get 50 mile plus loops in if possible.

 

[Erwin P]

The higher your speed the more you will gain from taller gearing.

 

[AbnormalWrench]

I was a bit suspicious the premise of this thread was questionable - that higher gearing on an electric motor would lead to higher efficiency. That makes perfect sense on a gas engine, because more load = higher efficiency on a gas engine. That isn't how electric motors tend to work. I haven't played with gearing, but I offer this link as something to consider. Electric motors have really bad efficiency at lower RPMs, they tend to be most efficient over 2000 RPMs. Assuming the stark drivetrain isn't some wildly different situation, you are not increasing your efficiency by going with taller gearing - in fact, you are probably reducing it.

The biggest thing that effects EV bikes is speed and throttle. The faster you go the crappier your range. And the more throttle you use, the crappier your range. If you cruise at 20-30mph you will get great range regardless what your gearing is.

The REAL Average Efficiency of an Electric Motor

What is the average efficiency of an electric motor? We used test data from 48 electric motors and found that the typical motor efficiency (percent) was...

www.tytorobotics.com

 

[Johnny Depp]

I was a bit suspicious the premise of this thread was questionable - that higher gearing on an electric motor would lead to higher efficiency. That makes perfect sense on a gas engine, because more load = higher efficiency on a gas engine. That isn't how electric motors tend to work. I haven't played with gearing, but I offer this link as something to consider. Electric motors have really bad efficiency at lower RPMs, they tend to be most efficient over 2000 RPMs. Assuming the stark drivetrain isn't some wildly different situation, you are not increasing your efficiency by going with taller gearing - in fact, you are probably reducing it.

The biggest thing that effects EV bikes is speed and throttle. The faster you go the crappier your range. And the more throttle you use, the crappier your range. If you cruise at 20-30mph you will get great range regardless what your gearing is.

The REAL Average Efficiency of an Electric Motor

What is the average efficiency of an electric motor? We used test data from 48 electric motors and found that the typical motor efficiency (percent) was...

www.tytorobotics.com

If 2000 RPM is optimal, that is exactly what taller gearing will help you stay closer to. Even if it’s not more range inducing, it definitely helps the right ability and pulls longer, power wheelies are much different. Only cost $100 for anybody to try.

 

[Theo]

I was a bit suspicious the premise of this thread was questionable - that higher gearing on an electric motor would lead to higher efficiency. That makes perfect sense on a gas engine, because more load = higher efficiency on a gas engine. That isn't how electric motors tend to work. I haven't played with gearing, but I offer this link as something to consider. Electric motors have really bad efficiency at lower RPMs, they tend to be most efficient over 2000 RPMs. Assuming the stark drivetrain isn't some wildly different situation, you are not increasing your efficiency by going with taller gearing - in fact, you are probably reducing it.

The biggest thing that effects EV bikes is speed and throttle. The faster you go the crappier your range. And the more throttle you use, the crappier your range. If you cruise at 20-30mph you will get great range regardless what your gearing is.

The REAL Average Efficiency of an Electric Motor

What is the average efficiency of an electric motor? We used test data from 48 electric motors and found that the typical motor efficiency (percent) was...

www.tytorobotics.com

Unfortunately, I doubt that the article you linked is relevant for our bikes: they write «This data has been collected and uploaded by the users of one of our electric motor test stands» and if you click the link in that sentence they show a BLDC motor test bench: brushless direct current; the Varg has a permanent magnet synchronous AC motor instead.
Secondly, the graph with high efficiency at more than 2,000 rpm has a top rpm value of 4,000: is it because it's only part of a bigger chart? I don't know, but the Varg reaches 14,000 rpm.
What I know is that, for an AC permanent magnet motor like ours:
• at very low rpm, the efficiency is lower than the peak for reasons I haven't understood yet,
• at high rpm the efficiency is reduced because of field weakening: basically, the motor behaves like a generator, too while spinning and this produces a voltage that goes against the one that moves the motor in the desired direction and this problem becomes more and more serious as the rpm increase. That's why the so called field weakening happens: some current is intentionally used to weakens the magnetic field of the motor so that it doesn't behave so much as a generator, but of course this is an inefficient way of operating it. With taller gearing, you delay the rpm at which field weakening is needed.

 

[Emmeffe]

rapporto 15/42
Zero Regen (freno di stazionamento)
L'impostazione della potenza è un fattore secondario, io la lascio sempre su 60 e la controllo con il polso anziché con un'impostazione.

Questa settimana ho percorso più di 46 km e ho finito con il 48% di batteria, un mix di single track compatto, un percorso pianeggiante e 3 piste MX sconnesse, per un totale di 3 ore con soste. Questo sembra aver sorpreso alcuni possessori che non hanno questo tipo di autonomia. Io sono un vecchio lento, 68 e cambio C.

La chiave è evitare lo slittamento delle ruote e abbassare i giri del motore. Se avessi fatto questa modifica al cambio solo per la guidabilità (non è mai stata male), ne sarebbe valsa la pena. Ovviamente l'autonomia è un vantaggio. Non porto nemmeno più il generatore e non ne ho mai avuto bisogno.

Con la coppia più elevata mai vista su una moto da cross (inclusa una Maico 700), questa moto riesce a gestire al meglio il rapporto di trasmissione, e ho la sensazione che Stark abbia commesso un grosso errore con il rapporto di serie. Un vantaggio collaterale è lo spostamento completamente arretrato dell'asse posteriore per migliorare le sospensioni posteriori e ridurre al minimo le impennate. La risposta dell'acceleratore è molto meno sensibile ai piccoli input e alle irregolarità del terreno, quindi è meno affaticante, più veloce e più efficace.

Se vuoi, puoi provarlo tu stesso, spendendo meno di 100 $.View attachment 14656

Ho fatto qualche ricerca e effettivamente ad alti giri il rendimento dei motori elettrici a magneti permanenti è più basso. Proverò anche io un rapporto 15/42