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Tech => Home Brew => Topic started by: IhaveaWelderandaDream on February 15, 2022, 01:37:03 AM

Title: Ebike Wattage Recommendation
Post by: IhaveaWelderandaDream on February 15, 2022, 01:37:03 AM
I'm working on converting a 90cc motorcycle to electric. I have been looking at a 5kw and a 10kw motor to run it with, but that seems pretty low compared to some of the commercial bikes I've seen.

I live in a pretty rural area so it's pretty much a requirement for it to hit 60-65 just to keep from getting tailgated. Are the listed wattage capable of hitting that mark? If not, what kind of wattage should I be aiming for? Any advice is appreciated.
Title: Re: Ebike Wattage Recommendation
Post by: princec on February 15, 2022, 01:43:57 AM
11kW should manage 70mph, just about, but that'll be flat out of course.

Cas :)
Title: Re: Ebike Wattage Recommendation
Post by: IhaveaWelderandaDream on February 15, 2022, 02:17:45 AM
Do you have any motor recommendations around that wattage?
Title: Re: Ebike Wattage Recommendation
Post by: princec on February 15, 2022, 02:32:11 AM
Me, no unfortunately but there's a few knowledgeable types around here who will be able to come up with something.
One thought: get a motor out of a crashed Zero FX. Insane of course but nobody said you had to be rational :P

Cas :)
Title: Re: Ebike Wattage Recommendation
Post by: TheRan on February 15, 2022, 03:49:51 AM
If it's a 90cc I'm going to assume you won't have much frame space to play with for the motor and battery. You could get 11kW out of a hub motor. The Stealth Bomber comes as a 12kW version and the 8kW model will apparently do 70mph.

https://www.gtelectricscooters.com/product/stealth-bomber-5000w-8000w-72v-80a-dirt-e-bike-2021/
Title: Re: Ebike Wattage Recommendation
Post by: hotsauce on February 15, 2022, 10:36:45 PM
If you're going with a hub motor, which is probably the simplest conversion, then I'd recommend the QS motors 12kW
https://www.qsmotor.com/product/17-inch-12kw-hub-motor/
I have it on mine and get a max speed of 85mph on a cold day with a 200lb rider off of a 72v battery. Probably shouldn't go more than 55 for more than a brief time though, to get the longest life out of the motor.
People will warn you about handling with the unsprung weight of a hub motor. In my experience it doesn't make a big difference, and probably only matters if you're going as fast as possible over really bumpy terrain.