First time electric motorcycle/scooter build questions

Hi!

I am building my first electric motorbike/scooter. I have some questions for the experienced builders and techs here. Mainly what I want to know is if you all think I will achieve what I am after with the build direction I am going in. Thank you in advance for any ideas and suggestions. I plan for this to be a twist and go chainless build. Simplicity is what I am after.

Here is what I am planning:

Custom stretched frame sorta boardtracker style with 26" fat wheels (same measure front and back, TBD street tires)
Custom leaf springer in the front and hard tail rear.
Tektro Dorado HD-E710 hydraulic piston disk brakes with ecutoff.
QS 205 5000w V3 3T winding motor, 72v/26.1ah battery, custom computer and controller kit from Leili in China
All led electrics to make it street legal plus horn and plate holder

Top speed I am after is 50-55mph for 2-3 miles max & adv cruise speed is 30-40mph on flat land. Distance desired is 15-25 miles on single charge. I live in the Caribbean and it's adv temp is 86 year round and high humidity with salty air. I am 5'8" and 170lbs.

Is this going to cut it or do I need to move up to the QS 273 8000w and something like 40ah(or more???) battery?

If you want to go 50, I do not recommend a hard tail rear.

One possibility: https://endless-sphere.com/forums/viewtopic.php?f=3&t=86342

First of all, notice that the swingarm seems to include the cranks. Haven't built a truly suitable example yet but I've worked on some (Now stolen) bikes experimenting putting that swingarm with the crank onto a Currie scooter. (That link said "FS" and I thought he'd mean a 'Missle FS,' a Currie scooter.) Fits in the back where the wheel is now and you find a good mount for the shock, then the forks with the shocks go on front. It's still a bicycle with those pedals, eh? My other Curries I put steel tubing across the front for some meathooks, you come up with a way to drive the wheel with the existing motor, or a replacement. There are 750w, 900w and 1000w Curries, not many parts needed on whatever conversions I've tried in the past, you can play games with controllers and overvolts but if you have too small a motor there's bigger that bolt in easy enough. I"m not saying I'm ready to believe that's a comfortable 50mph bike, but I'd say you might be closer. I don't think 8kw, etc., is really necessary but I haven't built such a think. I have a Pagsta, it's not clear if they were really 50cc or 100cc but the dang thing can do 50 (If you're patient) and at most have to be the equivalent of 2.5kw.

You could also take whatever hard tail you were thinking of and put a swingarm without cranks on there the same way, etc.

Dauntless said:

If you want to go 50, I do not recommend a hard tail rear.

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You could also take whatever hard tail you were thinking of and put a swingarm without cranks on there the same way, etc.

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I am gonna have a spring gel pad wide seat. I had a 110cc hardtail w/springer front before. The roads here are pretty good and very flat. Feel pretty comfortable with the frame.
My main concern is if I can get the speed and distance I am after. It's a 5000w Qs which I think can be over volted. The included controller is 80A sine wave and the battery is 72v 26.1ah. I am not sure the math and the calculators I found don't make a ton of sense to me.

The kit is pretty close to straight plug and play. The fun will be getting the ebrakes and lighting system & horn wired in correctly. Doesn't look too difficult and I work with a bunch of wiring savy guys.

I trust the op there, and harley. https://www.google.com/search?q=harley+hardtail&biw=914&bih=404&source=lnms&tbm=isch&sa=X&sqi=2&ved=0ahUKEwiZxNva44rSAhXKTSYKHeJqCBkQ_AUIBigB I'd prob go FS, and mimic something like zero for an enduro, but also would prob just stay with the benefits afforded by gas for on-road and when I'm going fast enough not to hear it.

Anyway, I'm unfortunately no expert, but can offer a 'Welcome!', and my amateur opinion that you'll be on the brink of your goal with what you propose.

Assuming standard bike aerodynamics and rolling resistance, what is the proposed rough total GVW (rider included)? How much will weight increase with the larger system? How important is money and acceleration?
Since you'll be very close with such a small battery, and the general good practice to oversize ev batteries, and since there's room for acceleration improvent of 5kw to 50mph, I'd opt of the larger system. Then balance wattage against range as desired. The lighter build will have less room to adjust and be inherently easier to over-stress both battery and motor.