Electric Bikes

[Gazza M]

It would be quite easy to incorporate the equivalent of pedal maps as well as a speed/torque limit into the controller as well to cover various different scenarios - surprised it hasn't been done yet!

Hypothetically if the motor can produce enough torque to wheelie the bike and some, you're not going to want any more at the peak. Generally this will be available across the full speed range (albeit with a drop at the top end as friction takes over) so the mid-range as you put will always be more than is possible to use which is a function of the centre of gravity and mass of the bike. So, the gearbox isn't necessary!

The only time you might want one is if you're wanting to run so the motor will be spinning too fast for its mechanical components to cope with, but if that's necessary the motor/final drive ratio has just been done wrong
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Past: '07 YBR125, '00 GPZ500S, '99 ZRX1100, '98 CBR600 track bike, '97 ZX9R
Present: '05 R6 track bike, 140 pit bike

[martin734]

[Nobby the Bastard]

[Kawasaki Jimbo]

Starting to think, "sock."

[Easy-X]

[Nobby the Bastard]

[Easy-X]

[Coby]

OK Dudes,

Would anybody like to explain, in simple terms:

Why did we invent the 'star & delta' starter for electric motors?

Why did we invent 1,2 & 3/ B,C & D Type circuit breakers?

[The Shaggy D.A.]

[Coby]

Why did we invent the 'star & delta' starter for electric motors?

Why did we invent 1,2 & 3/ B,C & D Type circuit breakers?[/quote]



No other electricians?

OK, in simple terms:

To absorb the 'massive' current flow requirements, associated with starting and accelerating an electric motor!

[Coby]

Listen Guys,

I don't believe for one minute that I'm more intelligent than anyone else, I certainly don't want to be thought of as some smart-arse.

But anyone who really is 'smart' must believe that as an old grizzled electrician, given my life's experiences, what I have to say on the subject of electric bikes has got to be worth a listen.

[Nobby the Bastard]

Are any of them mechanical gearboxes with multiple gears?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Coby]

Let's try to give you some figures; don't worry I'll keep it as simple as possible, I'm fully aware that electrical equations are enough to make the most mild mannered among us kick the shit out of their Labrador.

OK: You should of all seen this before at some point;

P=IV

Where - 'P' refers to Power, measured in Watts (or Kilowatts for our purposes).
- 'I' refers to Current, measured in Amps.
- 'V' refers to Potential Difference, measured in Volts.

Therefore a 2.3Kw electric motor, supplied at a potential difference of 230v, will draw current at a rate of 10amps.

or 230v x 10amps = 2300w

Therefore I can say that my 2.3Kw motor is going to draw 10amps when it's up and running.
Therefore I can choose a 10amp (motor rated) 'D' Type circuit breaker as my over-current protective device (that's just a glorified fuse really).

Now a 'D' Type 10amp circuit breaker has to be designed to absorb an initial starting current of....200amps!

[Nobby the Bastard]

You didn't answer the question.

How many of these are mechanical gearboxes with selectable gears?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Coby]

I guess what I'm saying is this:

If you road your ICE powered bike around all day in sixth gear, your fuel consumption would be diabolical!

Therefore if you run an electric powered bike around all day in top gear, the drain on the battery is going to be diabolical!

It stands to reason;


and the only complaint I hear about electric bikes is "the batteries don't last long enough".

I ain't surprised!

[Coby]

Sorry Nobby; in a world of my own.

What are you saying?

I'd have as many gears as an ICE engine given the choice; and change gear just like an ICE bike because it's the best bit about biking or driving for me.

You ride/drive on your gearbox, that's how you control a vehicle at speed.

[Nobby the Bastard]

[Coby]

An electric motor doesn't become efficient until it has stopped accelerating!

[Coby]

Look closely at how a 'star & delta' starter works:

You initially provide a three phase motor with power in a 'star' formation at 230v, therefore allowing the motor to draw massive amounts of current:

Only once the motor has almost reached optimum rpm do you then switch to the 'delta' formation at 400v, when the current flow then drops right off; and the motor becomes cheap to run.

[Nobby the Bastard]

[Easy-X]

Why this obsession with gearboxes? High powered eBike/eMotorBikes have either direct drive hub motors or simple "final gear" fixed systems.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Nobby the Bastard]

I was going to mention hub mounting because if they are small and light enough the lack of a final drive would offset the unspring weight cost of the motor, bearing in mind it can also replace the brake, removing that weight but I dont know enough about optimising the rpm for efficiency and speed.

It's a well and good using a motor that's efficient at 20k rpm but that's quite useless of that means about 400 mph.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[iooi]

[TheIncredible...]

[andy-b2]