Stark range video(s)

[vic321]

And still the Yamaha 450 only has around 50Nm on the output shaft. How can a ICE engine make more power at lower speed? Power is the multiplication of rpm and torqe. In reality an ICE engine can make more power at high speed. In an ICE engine the torque does not fall as drastic at high speed than in a BEV engine. So you can reach exorbitant power from a small ICE engine running at 30.000 rpm.

 

[Erwin P]

No a Yamaha 450 makes around 50Nm at the crankshaft. That is something 3 reduction gears removed from the output shaft.

An ICE can make more power at lower speeds because it can make more rpm at lower speed due to the greater reduction. Less torque but way more rpm makes for more power. If first gear only goes until 30 km/h it can make that 65'ish hp before that 30 km/h. A Stark doesn't have anything close to a 65 hp at that speed.

Edit: There is no reason an E couldn't do that too, but that would require a gearbox or a gearing that is so low that you sacrifice all topend speed for low speed grunt.
However the Stark as is has enough power that, again its smoothness and never being outside of the powerband, make it a very fast bike (apart from range issues etc).

 

[vic321]

Dont change your wording everytime. We speak about what comes out at the primary pinion. That is all that matters for us.
The reduction from primary pinion to the wheel is exactly the same in the Stark and the Yamaha. HP is NOT torque. Also please dont exchange these two words everytime.

 

[vic321]

These two graphics may help you

 

[Erwin P]

I don't change it all the time, but it might be a bit technical.
Oke, but we don't have the torque number of that Yamaha on the output shaft/primary pinion. So comparing is quite hard.

I have however taken some YZ450 gear ratio's from Chat GPT (but for our simple calculation that should do).
Lets asume 50Nm at the crank (all numbers given by a ICE OEM are at the crank). Primairy reduction (crank-clutch) is 2,6. First gear is 1,93.
50 * 2,6 * 1,93 = 250Nm at the output shaft/primary pinion. Awfully close to that Stark 275Nm isn't it?
If we then add the 14-48 sprocket reduction to the wheel we are talking 857Nm at the rear wheel. Were we to swap out the sprockets on that YZ (as i meant in that first reply) to lets say 12-53 we end up with 1104Nm. So it would be quite possible to have more torque with an ICE MX than the Stark has.

Edit: I Saw your dyno sheets too late so i used different numbers, but you get the picture. That is a WR450 so less power than a YZ450.

Edit 2: If both were 1 speed transmissions indeed the Stark would make a lott more HP on low speeds than the YZ450. However both are not 1 speed transmissions. The Stark has to make due with 1 long gear and the YZ450 has 5. If we asume 14k rpm is 160 km/h then it does not reach top power before 8k rpm or 91km/h or 60 hp (the same as a 450) at 5,5k or 62 km/h. By that time a 5 speed gearbox would be hamering top power for the 3th time.
If we asume peak power in first gear is around 30 km/h (so the full 60'ish hp). That would translate on the Stark to 2,6k rpm where it would only do something a tad below 30 hp.

 

[vic321]

Awfully close only for a very small band of rpm. And you cannot use it without using the clutch. Or your wheel will turn wild without moving you or your engine will die. also without movement.

 

[vic321]

Up to 8K rpm the Stark will give you double as much torque over the complete rpm range as the 450 does.

 

[Erwin P]

See my edit.

 

[vic321]

But you realize that you made the usable power band of the 450 so small, that it is useless?

 

[vic321]

You will never get the necessary speed to overcome the obstacle.

 

[vic321]

So with double as much torque in any rpm, you can build a secondary gearing that gives you double as much speed at the same torque.

 

[Erwin P]

I do realize that it is small and for that reason i think the Stark is superior, just not for it having more raw torque.

This one i've been looking for and superbly tells what i used a lott of words for.
Were you to change a sprocket on the YZ you could actually make fun of it having more rear wheel torque than a Stark. Since the SX450F actually makes more power than a YZ450 its not impossible that it's on the specsheet more torquefull on the rear wheel than a Stark.


Edit: That's why i think it's a bit unfair marketing from the EV OEM's to name the rear wheel torque. That number is always much bigger that the Crankshaft torque that the entire industry is using. And since 99%+ of people don't have a technical background that translates into wild claims like the Stark having 20x as much torque as a normal ICE while 1,2x comes closer to the truth if both were using the same metrics.

 

[vic321]

So when you need max torque (heavy terrain) the 450 just gives you a very small band, you have to keep by extensively using the clutch. Especially when you dont weant to climb the rock with 30mph. When driving faster, the Stark has always much more torque or HP as the 450. QED.

 

[vic321]

BTW you can also change the sprocket on a Stark. But it makes no sense due to overall much more usable torque.

 

[vic321]

The Problem on the Stark is not lack of torque, but the ability of the driver to transform the usable torque into movement.

 

[markhamr]

I was trying to keep away from comparisons as I said there's a lot of different factors.
Gearing was not the magic answer either. The bike rode better with the 13 front sprocket.
It developed push at low speed with the 14 and suspension windup which unloads the rear.
I just did it for range and too carry the front. It did make it better over all though and at least useable.
It did not make the bike any lighter and the constant firmware problems are even a safety issue.
By slow I meant the amount of times it just did not go at all or had some other issue.
Which has been a lot.