GNG Drive Gen2

spinningmagnets · Dec 7, 2012

roberthle · Dec 8, 2012

i took data on a bike ride and the top speed is 35mph. not bad for stock but i think this bike can handle higher speeds

Gab · Dec 9, 2012

Hi roberthle what application is that ? On android ?

Whiplash · Dec 10, 2012

HMM not bad at all for stock! What does it do in LOW gear? What are your sprocket sizes??

roberthle · Dec 10, 2012

the program is called Strava on the appstore.

I''m using a 11t in the highest gear. 32 is my lowest. What would you guys suggest to get more top speed out of it? I feel the torque is good but not at all strong to where it will wheelie like some folks say about their gen 1 kit.

roberthle · Dec 10, 2012

here is a graph showing a ride on level ground.

parajared · Dec 10, 2012

I think it would be pretty neat to put a 56 tooth chainwheel on it next to the 36. You likely couldn't use your derailer to change the gears, but you could stop your bike and use your fingers to move the chain.

According to my calculations with the motor spinning around max speed at 44volts you would see the following ranges of speed on a standard rear cassette.
36t= 10 - 31 mph (16 - 51 km h)
56t= 16 - 50 mph (26 - 80 km h)

Upping the voltage will make it wheelie easier and up the maximum speed, but you may rip chains, teeth, and interplanetary gears; also it will make it so that the efficient speed for the motor is way faster than you can peddle.

AlSpong · Dec 11, 2012

Hi, I'm new to this , I've been following the gng threads for a month or more . Can anyone help me understand how I can choose a motor that is going to be most efficient . I see a lot of posts that are about beefing up the output for maximum speed or hill rock climbing , but I want to build a bike that will be a good tourer , be able to carry a bit of wait , maybe deal with some soft sand from time to time and rough roads but nothing extreme .... I'm thinking of building a 12s A123 20ah pack and the gng mid drive interested me because it seemed that it might do more for less .
I was leaning on the 36 v side , but now there is a gen 1 and a gen2 , how do I compare these for my needs?
The gen1 looks like it has less moving parts and when it's not pushed is not problematic? Can anyone support or offer suggestions?

parajared · Dec 11, 2012

Brushless motors like to run around top speed. Most hit about 80% efficiency at their ideal rpm. When you are not in the efficient range they consume more power and generate heat. I say this because you want to run your motor around top speed if you want to go the furthest and not have to stop along the side of the road and wait for the motor to cool down.
This is why the GNG is a neat kit. You can change gears and keep yourself in that efficient range.

I have gen1 and I think gen2 looks better. My gen1 kit has reliability issues. 36v sounds good for GNG. A123 also sounds like a good battery.

For the dirt, your stock 38t chainwheel will push your bike up anything; your tire will lose grip before the engine runs out of power; however 38t will only get you in high 20s mph. For a good touring bike you may consider swapping for more teeth to get a higher top speed. A good 50t chainwheel can be had and easily swapped for around $40 assuming it will fit on your bike.

melodious · Dec 11, 2012

AlSpong said:
Hi, I'm new to this , I've been following the gng threads for a month or more . Can anyone help me understand how I can choose a motor that is going to be most efficient . I see a lot of posts that are about beefing up the output for maximum speed or hill rock climbing , but I want to build a bike that will be a good tourer , be able to carry a bit of wait , maybe deal with some soft sand from time to time and rough roads but nothing extreme .... I'm thinking of building a 12s A123 20ah pack and the gng mid drive interested me because it seemed that it might do more for less .
I was leaning on the 36 v side , but now there is a gen 1 and a gen2 , how do I compare these for my needs?
The gen1 looks like it has less moving parts and when it's not pushed is not problematic? Can anyone support or offer suggestions?

The gen1 kits uses a belt drive. Any debris (i.e. sand, dirt) wears away at it, unless you get some protective cover to deflect it.

IMHO, I'd get the gen2 36V kit. It's a brushless geared middrive system. It uses a chain. The motor sprocket "running the show" is a 9t, which can be easily replaced/upgraded to a higher tooth count from (I'm assuming your from the USA) websites that specialize in scooter parts, robotic parts, and custom metal fabrication (http://www.mcmaster.com/#). The gen2 kit run above 48V probably will see even more chain wear as you ride it more, unless you can feather your initial throttle. Once again, protecting the chain/sprocket from flying debris would only prolong it's life.

AlSpong · Dec 11, 2012

Thanks for your replies.... I am in Australia , we have a 250w law , or you need to have a motorbike license.... Soooo I'm thinking I don't want too much speed ... Just wanna keep that motor spinning at peak efficiency , not go too fast and hopefully appear invisible! Yes the motor will stand out , but what they see first is a cyclist going unusually fast ! So 20 mph, 32km/hr sounds reasonable ....... I kinda like the look of the belt drive aesthetically , but I'm interested in serviceability ..... Can those gears in the gen 2 be replaced easily ? Is it more efficient setup than gen 1?
Thanks in advance
Alistair from oz

melodious · Dec 11, 2012

Serviceability is still probably too early in the game of this motor. Haven't heard anyone doing it yet.

The gen2 have the more robust gearing material found in the current generation of geared hubs, so they last a while. As a stock setup, I highly doubt you ever get into any problems with your gearing, that is unless you push the gears with a ton of resistive torque.

Is the world really cracking down on 350-1000W E-bikes? You really want the 250W? The higher rated geared motors can typically be undervolted (i.e. 48V to 36V) to save on your battery capacity. And if you get bitten by the speed bug, you have the option of just upping your battery voltage.

Animalector · Dec 11, 2012

Fyi in Australia, if you have anything greater than 250 W whether you have a motorcycle license or not you will cop a fine.. Don't be disillusioned.

Plus side is, pedal hard and you will be left alone 98.4% of the time by everyone. Just get the kit and be sensible on the road

Andy

Geebee · Dec 12, 2012

If you get caught in Oz for over the 250w limit, I would take it to court as the new 250w limit is the rated continuous power, my UK legal bike is 250w but it's peak current is 17 amps at 36v, ie. over 600 watts.

RustySpokes · Dec 12, 2012

I have the Gen 1 kit on my bike, and as mentioned, provided you're always pedalling when it make sense to be, you should have no problems. Once I'm up to speed, I'm commonly well under 200W according to my Cycle Analyst, but I cycle partially for exercise. The extra watts really help with getting going, and for maintaining speed/reducing effort when you hit inclines.

heathyoung · Dec 12, 2012

Yeah I worried about the 250W limit but around here its only the stink bikes that get picked on. (Ie. 2 stroke)

Pedal like you should, dont ride like an ass and you will be fine.

I was commuting daily with 2.5KW - hehehe... Till I broke something (long story).

AlSpong · Dec 12, 2012

Yep, totally agree... I've seen the petrol driven mods get picked up by the cops in the city .... They're regular cop magnets although where I used to live that description could have easily applied to the rider. Now I'm in sw w.a, Margaret river ..... I think I will be fine , thanks for the tips and confirmation ...yes to those who don't know over 250w is illegal here and that's after a law change from 200w ... I think there is a speed limit too .... Which all in all the stay under the radar approach is one I'm going for ...... As far as taking it court ... It'd be easier to change to a 250w hub system ... Court cases can take years and money , lobbying government would probably be a better use of time ....... But while ebiked are still a novelty I think it's time to make hay and not worry too much, keep things close to legal spec ... But then its not like these motors have 350 printed on them in bold type either!

Geebee · Dec 12, 2012

I was suggesting that if a legal bike can pull 600w a home built should be able to as well, I was not suggesting breaking the law but it being applied evenly.
The previous 200w was supposed to be the absolute max wattage but none of the legal bikes were.

Cyclebutt · Dec 15, 2012

So how is the testing coming on this Gen 2 kit? I see I can order it (48v) for just over $400USD delivered by sea-mail. Anyone put this thing through the ringer yet? Miles? Crossbreak? Caijunze? Anybody?

Animalector · Dec 29, 2012

I am also interested to see some results of this latest kit...

Andy

mr.electric · Dec 29, 2012

Was the gen 2 GNG inspiration for converting a hub motor to a middrive?
The motor in this kit looks like a little hub motor.

crossbreak · Jan 7, 2013

mr.electric said:
Was the gen 2 GNG inspiration for converting a hub motor to a middrive?
The motor in this kit looks like a little hub motor.

It was not. I had this idea 2 years ago and build the first converted hub one year ago, so it could have happened the other way around.

mr.electric · Jan 8, 2013

Hillhater · Jan 8, 2013

parajared said:
According to my calculations with the motor spinning around max speed at 44volts you would see the following ranges of speed on a standard rear cassette.
36t= 10 - 31 mph (16 - 51 km h)
56t= 16 - 50 mph (26 - 80 km h).

Whilst 30 mph needs less than 1kW, you need to consider that in order to run at 50 mph you need 3+kW of power...probably closer to 4kW if you dont have narrow road HP race tires, and not wearing lycra !.
so, better be sure you have the controller and battery pack that can feed that level of power ! ( 80-90 A )

crossbreak · Jan 8, 2013

parajared said:
...
According to my calculations with the motor spinning around max speed at 44volts ...
36t= 10 - 31 mph (16 - 51 km h)
56t= 16 - 50 mph (26 - 80 km h)

Any idea about KV and phase resistance yet? Your nubmbers dont tell me much since I dont know your wheel size rather than what a standard cassette means to you.

Would someone who owns this motor a lab PSU and a multimeter be so kind and measure phase resistance for us?

GNG Drive Gen2

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