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Discussion Starter #1 (Edited)
Hi All,

THanks for the great resources here.
I leave in the south of france, passionate with motorcycles & I've been contemplating the idea of a cool vintage styled ebike, based on an eighties trail/ebduro, at an affordable price... I can't find that on the market today and I'm decided to test & try to do it myself.
I have moderate motorcycle mechanic competences but no electric competencies so I'd like to keep things simple.
Her is my plan :
- Find a bas bike (like that one for instance below)
- Add a motor, like that one here
- Add a battery & build housing here
- Do all the appropriate modifications


My goal is to have a 90 to 100Km/h top speed & 50kms range.
Do you think this combo works (I have no idea if the electric part fits) & meet my goals?
Thanks for your insights !

 

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Discussion Starter #2
Is it that my questions are wrong or that the members are more interested in cars or other? ;)
 

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Is it that my questions are wrong or that the members are more interested in cars or other?
Generally, cars.

You might have better success at Emoto ( http://www.elmoto.net/ ) or EMF (https://www.electricmotorcycleforum.com/).

We could give general advice, and there's some motorcycle people here, but a big part of having a successful project is knowing people who know the current meta of hobby. I.E. "No one does that anymore, that brand isn't reliable, what you probably want is X, but Y is easier to install for a beginner, here's where better prices are." And that kind of knowledge I think would be generally lacking here. Also, there are motorbike-specific concerns that they'll have a better head for than most of the people here.

My goal is to have a 90 to 100Km/h top speed & 50kms range.
Do you think this combo works (I have no idea if the electric part fits) & meet my goals?
The kit you selected was for a 3000w motor.

750 horsepower per watt, so, that's a 4hp motor.

I don't think that 4hp is enough for you to reach 100km/hr top speed. You probably need closer to 10 or 12hp (8000 watts), and 15-20 (12000 watts) would be more comfortable to still have some acceleration.

I am also skeptical of that little motor's ability to handle 3000w continuous.

Look at a motorbike chain, and then look at that delicate little this motor comes with. Looks thinner than a normal bike chain.


Let's consider top speed of the motor next, to see if it's geared appropriately:

The little sprocket is roughly 12 tooth, the larger one roughly 60 tooth, so, ~5:1 geardown. The motor says it's rated for about 5000rpm, so, about 1000 rpm at the wheel.

1000 revolutions per minute is 60000 revolutions per hour. You want 100km/h, so you need a tire circumference of 1.66 meters so that a tire rotating 60000 times actually rolls at least 100km. That's a diameter of 0.53m, which is 17.5"... that would be a pretty small tire, so, it looks like, roughly speaking, this motor can probably spin fast enough for a normal range of motorcycle tires to reach 100km/h.


... next, you chose a 3600watt-hour battery. (72v x 50ah = 3600 watt-hour)

Supposing you need 8000 watts to travel highway speeds, that 3600wh battery will last you 45% of one hour at that rate of discharge. At 100km/h, that's 45km. So, that battery is pretty close to what you'd need, and if you were driving slower like you usually would be at the starts and ends of your trip, you'd probably be okay. You only need 1500 watts to travel 70km/h (that's what most mopeds are, and about how fast they can go), so, at 70km/h you'd have 240km range.
 

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Discussion Starter #4
Thank you very much for that detailed on all matters answer.
I don't have a lot to reply besides doing what you suggested.

And I'll head to a more specialized forum (but google yeled yours first on "home made electric motorcycle forum" ;))
Have good day.
 
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