Joaquin Suavve
10 mW
What reduction from a 3000rpm to a 26" wheel seem to be the best?
Motor to Wheel Gear Reduction
- Thread starter Joaquin Suavve
- Start date
Joaquin Suavve
10 mW
Thanks for the smart ass reply! I stated in my introduction thread that I was electric bike "green horn" seeking useful advice. Not smug BS!
He's still right. You'll want to know your estimated speed range, torque capabilities of the motor you're using, if your battery can provide said current at your goal speeds...
Play around with this and see if that helps. For example, I input 3000rpm, 26in tire diameter, and at the bottom i enter 30 mph. The calculator tells me that i would require a drivetrain ratio of 7.73.
Play around with this and see if that helps. For example, I input 3000rpm, 26in tire diameter, and at the bottom i enter 30 mph. The calculator tells me that i would require a drivetrain ratio of 7.73.
Joaquin Suavve
10 mW
Top speed: 40mph (65kph)
Motor at this point: Lightning rod motors "big block"
I desire to "put to bed" the mechanics before exploring the batteries and controllers because electronics is not my strong point, will need a lot of study time.
Motor at this point: Lightning rod motors "big block"
I desire to "put to bed" the mechanics before exploring the batteries and controllers because electronics is not my strong point, will need a lot of study time.
scianiac
10 kW
- Joined
- Oct 24, 2018
- Messages
- 634
See that's more useful, the LR big block has a KV of 62 if I recall so does that mean you are planning on using a 48V battery? Either way top speed at 80% of unloaded speed (KV times voltage) is a very rough area to start IF you are using a controller without MTPA or Field Weakening. LR motors are highly salient IPM motors so respond very well to these, even if you don't drive it beyond the unloaded speed with MTPA (which is a safer idea) it will still have lots of torque at that unloaded speed where a motor driven just with FOC will have zero torque at that speed. So you could use like 100% for that multiplier for instance.
In actuality I wouldn't worry too much, assuming you have a controller that can dish out the amps and a decent battery voltage to work with the range of gearing is pretty wide for a big block, that is lack of starting torque or lack of speed is generally not an issue. It's more often more torque than you can actually use and more speed than it feels safe to go.
For instance I have my Small Block geared incredibly low, 27.4:1 to a 26in wheel, geared for 5-10mph crawling and it will still do 45mph on pavement with draggy DH tires at low pressures. Now that is dumping full phase amps into MTPA so that could cause issues overheating if done for long periods of time in addition to a possibility to instantly nuke the controller but you see my point, I tried to gear it for a top speed of 20mph and it blows past that without trying while having more torque than can really be used with the smaller motor. Of course vehicle and rider weight are a factor as well.
So get the gearing approximately correct, focus on a good controller and battery and then after you ride it you can always tweak the gearing later.
And as for the electronics if you aren't good with them I would just get the high voltage EV ASI kit, pretty much plug and play with the LR motors, all you really have to do is the battery which there are a good number of suppliers of high power batteries out there now. If you do want to do lots of learning then a quality VESC would be my pick, just don't get a cheap shitty one.
In actuality I wouldn't worry too much, assuming you have a controller that can dish out the amps and a decent battery voltage to work with the range of gearing is pretty wide for a big block, that is lack of starting torque or lack of speed is generally not an issue. It's more often more torque than you can actually use and more speed than it feels safe to go.
For instance I have my Small Block geared incredibly low, 27.4:1 to a 26in wheel, geared for 5-10mph crawling and it will still do 45mph on pavement with draggy DH tires at low pressures. Now that is dumping full phase amps into MTPA so that could cause issues overheating if done for long periods of time in addition to a possibility to instantly nuke the controller but you see my point, I tried to gear it for a top speed of 20mph and it blows past that without trying while having more torque than can really be used with the smaller motor. Of course vehicle and rider weight are a factor as well.
So get the gearing approximately correct, focus on a good controller and battery and then after you ride it you can always tweak the gearing later.
And as for the electronics if you aren't good with them I would just get the high voltage EV ASI kit, pretty much plug and play with the LR motors, all you really have to do is the battery which there are a good number of suppliers of high power batteries out there now. If you do want to do lots of learning then a quality VESC would be my pick, just don't get a cheap shitty one.
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Okay, you want real power.
40mph is about 500rpm.
You need two stages.
Here's my 'just throw money at it' method for easily having the 1st stage done.. then you just need to build a mount.
Why shouldn't i build a Neumotor RC + planetary gear reduction drive?
40mph is about 500rpm.
You need two stages.
Here's my 'just throw money at it' method for easily having the 1st stage done.. then you just need to build a mount.
Why shouldn't i build a Neumotor RC + planetary gear reduction drive?
Joaquin Suavve
10 mW
I built my own planetary gear box for the Honda 50cc (19:1) and it could have been reused if I hadn't given it and the motor to a friend that had since died. I'll try to reach out to his wife, but doubt it is still around.
You can see in one of the photos on multiple intro thread.
You can see in one of the photos on multiple intro thread.
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I guess I missed the intro thread too. Is that a new thing here? I’m not currently one of your followers so I feel like I’m playing catch-up now.
Joaquin Suavve
10 mW
Joaquin Suavve
10 mW
Here is my planetary reduction inside case on the screen and the parts for the hydraulic clutch. This was in 2014!
Here is a closer look at the planetary gear set.
Here is a closer look at the planetary gear set.
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