Hi everyone! I'm new to this forum so I should introduce myself. I'm a 24-year old guy from Finland who got really excited about E-bikes a few months ago. Since then I've read alot of this forum and decided to start my own build thread.
My experience with bicycles isn't too great, I know the basics and that's about it. With the RC-cars though I've played alot as a hobby in the past and later I studyed electronics. Jobs here in Finland were a bit tough to get so I decided to get education on different area and nowadays I'm working as a car collision mechanic (dunno what's it called in english). So electronics doesn't implement so much at my work now, but it is still fun to play with and that's one reason why I got excited about e-bikes. Second reason is that battery technology has improved so much from those days when I played rc-cars using nicads and nimhs. But that's about me, let's get to the build before this gets boring!
So my plan is to build something light, powerful , dead simple and reliable without spending k's of €€€ in it. This far I have bought a Kona Stinky from my buddy for cheap 400€. After watching some youtube videos I thought a 2wd hub motor build would be so badass, but I soon realised it's gonna be way too heavy and I'd probably mangle my rims at the first jump so I dropped the whole idea. Next idea was a mid-drive, where I still am, especially GNG got my attention when I saw what has been achieved with that setup. That looked so promising but the more I read about it, the more I got frustrated. Kit's price is 384€ including postages and what I've been readin' the only good thing in that kit is the motor! Controller is propably ok but it doesn't deliver the amp's what I'm seeking for, so that goes to thrash can aswell and everything else delivered with the kit goes there too.
Power aim in this build is above 4kW, so to get the bike reliably deliver that power to the rear wheel, I abandon bicycles original drivetrain and build it with 219 chain and sprockets. This way I can make it single stage reduction and the drive train doesn't eat too much energy.
As the title says I'm going to ditch the pedals too. This is for keeping things simple and there will be many advantages this way for example I can abandon that crappy front freewheel thing and use a bigger motor and put it infront of the bb. I planned on hooking pedals in the bb and run the chain straight from the motor to the rear wheel. It's yet to be seen do i have to use any idler in this setup, bcoz I plan to make the motor sheets adjustable so I can adjust the chain tension by motor.
What comes to the motor, I was very happy to find this big block GNG motor, it does look very promising and I hope to get more info about that motor like kv and max kW. So if anyone knows anything about it, let me know, I'd appreciate it very much! One reason why I started this thread is that I need help with certain things like controller, throttle and calculations, so if anyone has any recommendations I'd like to hear them.
GNG 450w motor has 67kv iirc, so a big block may have a smaller kv, but I made my calculations with that 67kv. So I planned to use an 18s Lipo coz what I've read here is that with the 450w motor, the eddiecurrent loss grows after those voltages. Correct me if I'm wrong I'd like to use even more volts if it makes any sense! What I don't know is how that big block reacts to higher volts, is the problem even worse?
This is my idea in a nutshell so tell me your thougths, ideas and improvements, any comments are welcome!
Here's some calculations:
450w motor is 67kv. Batteries I plan to use are 18s so that makes 74,7v if I charge cells to 4,15v. So the motor will rev 5005rpm max, so 70% of that would be 3503rpm. As I told earlier I planned to use the 219 chain and sprockets and that's because it will be much tougher than a bicycle chain and the chain pitch is much smaller so I can get very reasonable reduction with only single stage. The front sprocket would be 12t becouse everything under that would make terrible noise, severe wear and lumpyness as we know. The rear sprocket is 92t, biggest I've found yet, that will give me final drive ratio of 1:7,67, which is pretty descent with strong motor. So the rear wheel maximum rpm under load would be 456,7rpm, that makes 56,4kph with 26" rim. If we assume best efficiency would show about 40-60% load rpm, then it would be best to drive from 23 to 34kph. That's about what I'm seeking for, because this thing will be driven in the woodz.
Harri
P.S. I'm really sorry about this novel.
My experience with bicycles isn't too great, I know the basics and that's about it. With the RC-cars though I've played alot as a hobby in the past and later I studyed electronics. Jobs here in Finland were a bit tough to get so I decided to get education on different area and nowadays I'm working as a car collision mechanic (dunno what's it called in english). So electronics doesn't implement so much at my work now, but it is still fun to play with and that's one reason why I got excited about e-bikes. Second reason is that battery technology has improved so much from those days when I played rc-cars using nicads and nimhs. But that's about me, let's get to the build before this gets boring!
So my plan is to build something light, powerful , dead simple and reliable without spending k's of €€€ in it. This far I have bought a Kona Stinky from my buddy for cheap 400€. After watching some youtube videos I thought a 2wd hub motor build would be so badass, but I soon realised it's gonna be way too heavy and I'd probably mangle my rims at the first jump so I dropped the whole idea. Next idea was a mid-drive, where I still am, especially GNG got my attention when I saw what has been achieved with that setup. That looked so promising but the more I read about it, the more I got frustrated. Kit's price is 384€ including postages and what I've been readin' the only good thing in that kit is the motor! Controller is propably ok but it doesn't deliver the amp's what I'm seeking for, so that goes to thrash can aswell and everything else delivered with the kit goes there too.
Power aim in this build is above 4kW, so to get the bike reliably deliver that power to the rear wheel, I abandon bicycles original drivetrain and build it with 219 chain and sprockets. This way I can make it single stage reduction and the drive train doesn't eat too much energy.
As the title says I'm going to ditch the pedals too. This is for keeping things simple and there will be many advantages this way for example I can abandon that crappy front freewheel thing and use a bigger motor and put it infront of the bb. I planned on hooking pedals in the bb and run the chain straight from the motor to the rear wheel. It's yet to be seen do i have to use any idler in this setup, bcoz I plan to make the motor sheets adjustable so I can adjust the chain tension by motor.
What comes to the motor, I was very happy to find this big block GNG motor, it does look very promising and I hope to get more info about that motor like kv and max kW. So if anyone knows anything about it, let me know, I'd appreciate it very much! One reason why I started this thread is that I need help with certain things like controller, throttle and calculations, so if anyone has any recommendations I'd like to hear them.
GNG 450w motor has 67kv iirc, so a big block may have a smaller kv, but I made my calculations with that 67kv. So I planned to use an 18s Lipo coz what I've read here is that with the 450w motor, the eddiecurrent loss grows after those voltages. Correct me if I'm wrong I'd like to use even more volts if it makes any sense! What I don't know is how that big block reacts to higher volts, is the problem even worse?
This is my idea in a nutshell so tell me your thougths, ideas and improvements, any comments are welcome!
Here's some calculations:
450w motor is 67kv. Batteries I plan to use are 18s so that makes 74,7v if I charge cells to 4,15v. So the motor will rev 5005rpm max, so 70% of that would be 3503rpm. As I told earlier I planned to use the 219 chain and sprockets and that's because it will be much tougher than a bicycle chain and the chain pitch is much smaller so I can get very reasonable reduction with only single stage. The front sprocket would be 12t becouse everything under that would make terrible noise, severe wear and lumpyness as we know. The rear sprocket is 92t, biggest I've found yet, that will give me final drive ratio of 1:7,67, which is pretty descent with strong motor. So the rear wheel maximum rpm under load would be 456,7rpm, that makes 56,4kph with 26" rim. If we assume best efficiency would show about 40-60% load rpm, then it would be best to drive from 23 to 34kph. That's about what I'm seeking for, because this thing will be driven in the woodz.
Harri
P.S. I'm really sorry about this novel.
