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Author Topic: Motorbikes < 1000 cc by torque  (Read 637 times)

Moto7575

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Motorbikes < 1000 cc by torque
« on: January 20, 2019, 12:56:18 PM »

The first production models in the list are electric motorcycles.

* : turbine engine (the 1st in the list cost 160.000 euros, an helicopter engine turbine)
**: electric
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hubert

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Re: Motorbikes < 1000 cc by torque
« Reply #1 on: January 20, 2019, 03:21:15 PM »

What torque is it? On motor shaft or on the wheel?

The guys always chatting about engine torque make me smile, because the effect depends on the transmission ratio. Even the torque at the wheel end has to be divided by the wheel radius to get the thrust. In fact, the only significant figure for "performance" is the thrust you get from the powertrain. Simply expressed in Newtons. Or (old)tons!

Thrust is the parameter you can drive an acceleration from. Same as with rockets.
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Moto7575

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Re: Motorbikes < 1000 cc by torque
« Reply #2 on: January 20, 2019, 03:38:10 PM »

Not false Hubert. Real parameter would be "size of the kick in the ass" =f(torque, ratio, weight, transmission efficiency). Unfortunately it does not exist. What is left is 0-60 mph or 0-100 kmh times...
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Killroy

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Re: Motorbikes < 1000 cc by torque
« Reply #3 on: January 21, 2019, 11:42:46 AM »

Power vs Torque is often misunderstood as other people have already pointed out.

I advise that Torque numbers should typically be ignored.  The quality or shape of the torque is more important.

Power is a function of torque and speed. You should pay attention to those numbers.   8)
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Doug S

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Re: Motorbikes < 1000 cc by torque
« Reply #4 on: January 21, 2019, 09:01:56 PM »

I agree with Hubert. Torque is a useful number to compare if we're talking about similar machines. ICE vehicles with gearboxes giving similar overall gear ratios, for instance. Or EVs, again with similar gearing. But it's not too helpful if you're comparing an ICE vehicle with gearbox to an EV without. Of course the relationships between motor torque, gearing and vehicle acceleration are pretty simple and well understood, but it's just not intuitive.

But thrust is the linear force pushing the vehicle (and driver) forward, which is proportional to acceleration (Newton's second law: F = m*a). Of course it's also a fairly simple function of the torque produced by the motor and the overall gearing of the vehicle...but more importantly, it's what you feel pushing your butt into the seat. It's relatable in a fundamental way by anybody who's ever ridden a motorcycle. It's what makes a bike feel quick (as opposed to fast).

I think it's a better way of comparing vehicles on an apples-to-apples basis. Doesn't matter how you generate it, gearbox or no, a vehicle with more thrust will accelerate harder.
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Richard230

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Re: Motorbikes < 1000 cc by torque
« Reply #5 on: January 21, 2019, 09:10:46 PM »

For me, it is not the amount of torque an engine produces, but the shape of the power curve.  The broader and more level the curve, the more powerful the vehicle will feel while you are riding it.  That is what I like about an electric motor. The power curve is almost completely flat across the rpm range. This gives the feeling of your vehicle being more powerful than the maximum torque numbers would indicate.  Most people will prefer riding with a motor having this kind of power curve.   :)
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hubert

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Re: Motorbikes < 1000 cc by torque
« Reply #6 on: January 22, 2019, 12:01:57 AM »

Yes! In fact the "flat power curve" of an EV is not really related to the motor. It is rather the power handling ability of the battery. Somehow the power (or torque...) will be limited via software by the motor controller in order not to exceed battery's maximum amps rating and also not to get overheated or undervolted or so.
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