Electric Motorcycle - Where to start?

[quelsurprise]

If you want good acceleration torque even as you approach max speed, you'll have to gear it for a higher speed by some amount. I'm not sure exactly how much, but you can use the ebikes.ca motor simulator to get the approximate idea--the torque curve it has will intersect the speed curve at the point you don't get any faster. Change parameters (voltage, current, and/or gear ratio for a middrive) until the torque is still as high as you want it to be while at the maximum speed you want to go.

Thanks!
I'm still not 100% sure if I have the custom motor settings correct, will be digging into J Bjork's posts to compare what they'd used.

Is it the case that motor torque starts decreasing once the supplied voltage reaches half the battery voltage, or did I dream that? if it is true, what's the best terminology to start searching and understanding that with?

 

[amberwolf]

AFAIK motor torque should be greatest when there is the highest phase current, which is at the lowest possible RPM, since that is when there is the least BEMF generated by the motor's spinning to oppose the incoming phase current. This is the blue line on the graph.


Motor *power*, however, is torque x RPM, so that probably does peak at half the full speed of the motor (which would be at about half the battery voltage, with no load). This is the red line on the graph.

 

[quelsurprise]

Hi, I've been seeing what I can use for the jackshaft set up, and seems like I should be able to go with Gates 8m 21mm Carbon belt and pulleys, think I've figured a way to mount the pulleys, rfndzc advised that I can just use one of the QS180 splines with a key Belt drive conversion on honda CB350F, but I've been enjoying Fusion360 so just put in an order with sendcutsend to see if this'll work in between the motor shaft and pulley taper bushing.

Also been playing with gear ratios, planning to design the motor/jackshaft mount so I can tension the belt by moving the motor, and also allowing enough movement to accommodate a few combinations of pulleys if I need to change the ratios.

Here's what I have so far, if I go with a 110v battery it should do 70mph at around 50% of the battery, at which point the effects of bemf will start to be noticed, if I've understood this correctly, maybe? thanks Amberwolf for the responses. I loath using spreadsheets but chatgpt helped me get together some formulas so I can easily see what different combinations should yield.