Posts
96
Joined
6/3/2019
Location
Jackson, WY
US
Edited Date/Time
3/26/2022 4:39pm
Long time lurker who doesn't post much. Before I get into the math, I wanted to point out I have no political bias or nostalgia bias. I own a Tesla and a diesel truck. I own a 2 stroke dirt bike and a 2 stroke turbocharged snowmobile. The common thread among all these vehicles is applying the right technology for your intended purpose.
I didn't read all of the 28 page Stark VARG thread, but I did start doing some basic math, all of which suggests it is highly unlikely the company's run time estimations are within the realm of realty.
Some baselines for everyone.
Stark VARGs battery size 6kw/h -- Claimed Range: "up to 6 hours" or say 30 minutes of MX style riding.
Alta Redshift battery size 5.8kw/h -- Claimed Range: "up to 4 hours of riding in the woods" - real life ended up about 90 minutes. *could* be run about 25 minutes of hard moto riding.
Zero SRS battery size 15.6kw/h - Claimed range ~110 miles
Tesla Model Y - 75kw/h - Claimed range 310 miles (which you can do in perfect conditions/tires/wind/driving etc).
Before I go further, we all know there are massive efficiency losses off road for a myriad of reasons including rolling resistance, wheel spin, elevation gains losses, "race" style riding (hammering on brakes and throttle) etc.
To try and make an apples to apples comparison, one gallon of gas is the equivalent of 33.7 kw/h (according to science). This means your normal moto bike has about 54 kw/h of power onboard (or roughly 2/3 the size of a Tesla battery pack!)
ICE however only has efficiency of around 30-35% versus a Tesla of around 80-94% efficient (newest supposed to be around 90-94% efficient).
So, adding these figures in...
Standard 1.6 gallon moto bike @33% efficiency has about 17.8kw/h vs a Stark at 6kwh running at 95% (lets give them the benefit of the doubt) about 5.7kw/h efficiency.
That's right, about 1/3 the energy of a fully gas'd up MX race bike (and 1/5th an off road bike w larger tank).
Stark can get some additional efficiency through regenerative braking, output controls etc. However, I don't think I'm alone in thinking they are *****wildly***** out of line with their claims, especially for the off-road guys.
I'd say "oh, battery technology will improve drastically over the next handful of years" but I don't think that'll happen for the $13,000 dirt bike set (we'll see it for the $100K car driver set).
I want to be proven wrong, but after listening to the CEO talk, I got some serious Elizabeth Holmes vibes.
Someone please chime in and show me where my math is off.
EDIT: I did some research on the mechanical efficiency of engines. More than likely, a 4 stroke dirt bike motor is very efficient when it comes to actually turning gasoline into mechanical (kinetic) energy (as opposed to thermal energy). My data point of 30-35% is probably accurate. This is not to say dirt bike engines have good MPGs, its just to say when energy is put into the motor, about 1/3 of it is going to be turned into rotating (mechanical/kinetic) energy. MPG, vehicle efficiency, etc are all driven by other factors.
I didn't read all of the 28 page Stark VARG thread, but I did start doing some basic math, all of which suggests it is highly unlikely the company's run time estimations are within the realm of realty.
Some baselines for everyone.
Stark VARGs battery size 6kw/h -- Claimed Range: "up to 6 hours" or say 30 minutes of MX style riding.
Alta Redshift battery size 5.8kw/h -- Claimed Range: "up to 4 hours of riding in the woods" - real life ended up about 90 minutes. *could* be run about 25 minutes of hard moto riding.
Zero SRS battery size 15.6kw/h - Claimed range ~110 miles
Tesla Model Y - 75kw/h - Claimed range 310 miles (which you can do in perfect conditions/tires/wind/driving etc).
Before I go further, we all know there are massive efficiency losses off road for a myriad of reasons including rolling resistance, wheel spin, elevation gains losses, "race" style riding (hammering on brakes and throttle) etc.
To try and make an apples to apples comparison, one gallon of gas is the equivalent of 33.7 kw/h (according to science). This means your normal moto bike has about 54 kw/h of power onboard (or roughly 2/3 the size of a Tesla battery pack!)
ICE however only has efficiency of around 30-35% versus a Tesla of around 80-94% efficient (newest supposed to be around 90-94% efficient).
So, adding these figures in...
Standard 1.6 gallon moto bike @33% efficiency has about 17.8kw/h vs a Stark at 6kwh running at 95% (lets give them the benefit of the doubt) about 5.7kw/h efficiency.
That's right, about 1/3 the energy of a fully gas'd up MX race bike (and 1/5th an off road bike w larger tank).
Stark can get some additional efficiency through regenerative braking, output controls etc. However, I don't think I'm alone in thinking they are *****wildly***** out of line with their claims, especially for the off-road guys.
I'd say "oh, battery technology will improve drastically over the next handful of years" but I don't think that'll happen for the $13,000 dirt bike set (we'll see it for the $100K car driver set).
I want to be proven wrong, but after listening to the CEO talk, I got some serious Elizabeth Holmes vibes.
Someone please chime in and show me where my math is off.
EDIT: I did some research on the mechanical efficiency of engines. More than likely, a 4 stroke dirt bike motor is very efficient when it comes to actually turning gasoline into mechanical (kinetic) energy (as opposed to thermal energy). My data point of 30-35% is probably accurate. This is not to say dirt bike engines have good MPGs, its just to say when energy is put into the motor, about 1/3 of it is going to be turned into rotating (mechanical/kinetic) energy. MPG, vehicle efficiency, etc are all driven by other factors.
If that time is not acceptable, its only a matter of more time until the battery technology meets expectations and I doubt that will be long.
Technology isn't there.
Anxiously awaiting to hear I'm wrong from someone quantitative.
The Shop
I don’t have better numbers for you, but just looking at the type of engine and conditions it requires to even get to 30% efficiency, then looking at a dirt bike where we tune for max hp, slip the clutch, bounce the limiter, and blast the intake port with a bunch of extra fuel literally every time the rider twitches his wrist, I just don’t see them as being in the same ballpark.
Edit: I’m not saying Stark can or will live up to its claims, just pointing out that your math might be unintentionally favoring the current mx engine.
Another way we could look at the math is in terms of horsepower used. Take supercross for example, it's all bursts of throttle, nothing really sustained like outdoors, save for the whoops. If you were off the gas 2/3's of the time and full throttle 1/3 of the time, that 60hp bike is using 20hp on average? Or, 15kw? Or, 5kwh used in a 20min main? Might be enough.
With that said, never trust a salesman in a turtleneck. Shit, don't trust anyone in a turtleneck.
Until you've collected that data, no one knows whether it's good enough, LOL.
As I see it... at the end of the day.... Gas equals lighter, longer runtime, and easier power delivery... electric equals quiet, heavier, less runtime, and more overall rip...
Another thing that should go into the equation is how long a ICE bike lasts with a full tank of gas. How much does a 450 consume in a 30 min moto? A gallon?
Edit:
I‘m really curious too see how long the bike lasts and if it’s a viable option for a day‘s training without a possibility to charge in between motos.
It looks like from the photos that the motor and the inverter are water-cooled and that there’s a heat exchanger in the back of the bike.
Pit Row
I love the electric technology, less maintenance, less noise...I'm excited to own one....but I'm not going to pay $15K for 30 minute battery life, (Possibly?) subpar performance and to a company with no history (I don't want to be without parts/service a few years after buying).
Edit: Jeff calculated with 1.6 gallons. So that was correct, but also over 1/4 gallon more than the Japanese brands have.
On race weekend he burns 2.5 gallons of T4 in his 450 race bike.. Apx 20-25 laps practice on Saturday . 2 classes
on Sunday apx 20 laps. Totaling 40 laps @ 110 sec per lap total 74 minutes of riding or 1 gallon per 29 minutes.
So to save the planet he is gonna buy the Power Max 5000 EV moto bike.
Friday night charge of battery assumed 4kw gen runs 4 hours for charge . ( .71 gallons per hour per an RV forum)
so 2.84 gallons. New bike so battery is at 2% charge.
So he tops off battery in between practices for an assumed hour of run time .71 gallons
He will recharge it sat night to be ready for Sunday so 3 hour assumed to be at full power so 2.13 gallons
Total fuel burnt for an EV moto bike 5.68 gallons. On race weekend.
Possibly he could pull a 30' gooseneck trailer to the track with solar panels on it. Then sell off excess power at the track? How will this charge at night Or sometimes we have clouds? Store it via Battery packs maybe then convert it back to 110v, 220v or what ever is needed??
This truck & trailer is in addition to his Diesel truck & 5th wheel toy hauler. His wife & kids wanted to come.
20 -25 gallons for 200 mile round trip. Each of his 2 trucks.
Power from wall at home , Coal, Gas/ oil, Nuclear , hydro, wind, solar . The last 3 are a drop in the bucket of the supply needed.
He's hopes they don't ban Generators . Or he will need 2-3 spare battery packs for a race weekend. Off road guys 4 with pit stops? 1k, 2k, 3k each??
He has to do something Right? So EV is the answer & no pollution . I'll try to explain this but he is fast not smart>>
The Horse & buggy was replaced naturally as automobile technology became better. This wont be allow to happen that way?
Add in 15k for the bike, He may have to give up Smoking, Drinking , Weed & definitely no side piece to afford all this. First world problems..
Can you help? Any suggestions? All I have for him is give up & get a e- MTN bike. # wut?
Also this board: “hey, look at this electric bike with a 60hp and 80hp model. Especially with the instant torque that isn’t rpm dependent, it will dominate 450s. I can’t wait until they have more availability.”
To get this.
You have to do that.
But this is worthless.
Without that.
So no matter what, to ride this.
I need that.
So why don’t I just put that.
In that.
Post a reply to: Stark's (crazy) claims and the reality of off road EVs