GNG, 1000W 48V BB-drive, $400

[gknowes]

lightningrods, are you going to have a website where we can go , to see all the goodies you have to sale ?

 

[LightningRods]

lightningrods, are you going to have a website where we can go , to see all the goodies you have to sale ?

Gary, your timing is perfect. The domain just went live today. It's www.lightningrodev.com . Currently there's nothing there but a couple of tutorials moved over from my studio site. I'm going to get busy and build an informative site with all of my parts, tutorials, e-bike info and an online store. I really want to be a resource for this hobby. My background is technical illustration so as I keep learning how to build e-bike parts I'll keep sharing the information.

 

[rodgah]

I doubt I am the only one that has seen a general shift in the non hub section towards predominately GNG threads/builds. Not a bad thing by any means, anything that is cheap and works is great for this community getting a wider population involved. Lightning rods your developments are excellent making the cheerfull gng a real contender. I am wondering if there is enough interest to develop the drive around a 'given' frame. Obviously there is the problem with one size does not fit all, but there might be enough people in a certain genre to accommodate that. Just a thought. Frames like the DMR bolt, fireeye match, commencial absolut sx, Kona bass.....all dj'ish freeride frames but in large size wouldnt be too uncomfortable, optional gearing or singlespeed, middle ground suspension definitly not dh travel but enough.

 

[LightningRods]

Hi Rodgah- I love your high end builds. Matt's DiVinci drives with Astro 3220 are a great drive system. What a lot of us are trying to do with the GNG is what modders have been doing with '32 Fords, '55 Chevy's, VW Beetles and Honda Civics for a long time. If you have the money you can go out and buy a Porsche. If you have the knowledge and money you can build a race car from scratch, which is basically what you've done. Like any good hot rodding platform the GNG has potential. The motor is very solid and a fantastic deal for the money. The rest of the kit really just gives you a framework to work in. Every part of it besides the motor really needs upgrading to be good for much.

I chose a Specialized Hard Rock 29 hard tail for my build because they are very common bikes and again a great value for the money. I agree with you that "one size fits all" doesn't really work very well. I'm going to make some formed frame attachments for the upper sheets and a battery box. I'd like to be able to offer a kit to people that fits properly, works properly, and doesn't leave them with a lot of frustrating loose ends and no instructions.

I've crawled through your Electra-Punk build thread and was inspired by your design and craftsmanship. I'm looking forward to checking out your other builds. Cheers!
Mike

 

[skyungjae]

While doing some cleaning and lubing on my Stink-E, I decided to flip my belt in the other direction:

This is what my original GNG belt looks like after about 600 miles. I wonder how far I can take it.

 

[Tinto]

Wow! Great longevity effort.
I've been through 3 and I'm at around 600km.
You sanded / filed the small belt wheel didn't you?
I remember you giving me that advice, it will be the next thing I work on!
4 new belts are on their way to me at the moment.

 

[Secret1511]

Hello,

Question.
I try to get the adapter out of the big pulley. It is stuck. Any advice?

 

[speedmd]

Impact is the best method to get stuff apart! Small hammer and solid piece of soft metal (aluminum, brass, copper) hitting on the knock out areas of the pulley while holding the center hub from spinning freely. You may need a extra set of hands.

 

[skyungjae]

Wow! Great longevity effort.
I've been through 3 and I'm at around 600km.
You sanded / filed the small belt wheel didn't you?
I remember you giving me that advice, it will be the next thing I work on!
4 new belts are on their way to me at the moment.

I actually never rounded down the sharp edges on the output shaft pulley. I always planned on it when I had to swap the belt out, but I just felt it wasn't necessary with my belt wear. When I did take the belt off, the edges on the small pulley were indeed sharp. Perhaps when I put a "new" belt on, I'll do something about it.

What I've been doing is really watching the torque through finer throttle modulation. I also make sure I'm already moving or give a little more pedal when I'm initially applying the throttle so there's less shock from that almost on/off power. There are times when I do start from a stop with the throttle as well as full throttle it up hills, but I try to make the power delivery as smooth as possible. It probably also helps that I'm usually pedaling all the time though my pedal effort is probably similar to a normal person just cruising on level ground.

I'm waiting for LightningRods' complete line up before I decide on any upgrades.

 

[speedmd]

Hi Skyungjae

Great riding getting this to last as long as you have. Good advise also.

I have been doing the opposite with my chain modded kit. Burning out in the gravel drive way while leaning over the bars, flipping it over doing wheelies while clipped into the pedals , trying to climb stuff from a stand still that it just can not do while in too big a gear . I know something is going to break Still not any play in the little chain . Dog hates the sound of this bike and I hope we can make friends with it. :?

 

[skyungjae]

Hi Skyungjae

Great riding getting this to last as long as you have. Good advise also.

I have been doing the opposite with my chain modded kit. Burning out in the gravel drive way while leaning over the bars, flipping it over doing wheelies while clipped into the pedals , trying to climb stuff from a stand still that it just can not do while in too big a gear . I know something is going to break Still not any play in the little chain . Dog hates the sound of this bike and I hope we can make friends with it. :?

Despite wider belt options being available via LightningRods, I'm starting to think that his future chain drive options may be the way to go. It seems like, due to the less wrap, some people are getting teeth jumping on belts using just the adjustable sheets alone. Of course there are other factors that may come into play such as improper alignment or not enough tension, but I'm not sure if a wider belt kit will remedy this. This is why I want to wait for everything he has to offer than simply get the slip on sleeve pulley and adjustable sheets.

We'll see. I'd love to let loose doing wheelies and burn outs. Unfortunately, I am running into a battery problem since I've done my shunt mod. I think I'm overusing my Zippy LiFePO4 packs and will have to find a more suitable power source. At about 4Ah, if I put the batteries under heavy load, the voltage will sag under 41V and that causes my 44V LVC, set by my Cycle Analyst, to cut power. If this happens while going up a steep hill, the power cutting in and out will cause the belt to jump teeth. This used to happen when I was at around 6Ah...

 

[Secret1511]

Impact is the best method to get stuff apart! Small hammer and solid piece of soft metal (aluminum, brass, copper) hitting on the knock out areas of the pulley while holding the center hub from spinning freely. You may need a extra set of hands.

Thanks man. Heating up did it!!!

 

[speedmd]

Great, it came apart easy. If you plan on reusing the hub, I would file some opposing flats on the small barrel section for a spanner to hold it while you unscrew the pulley. Never seize the threads also. I have a small box full of new unused original parts for this kit now.

Best wishes on the chain drive mod.

 

[LightningRods]

Despite wider belt options being available via LightningRods, I'm starting to think that his future chain drive options may be the way to go. It seems like, due to the less wrap, some people are getting teeth jumping on belts using just the adjustable sheets alone. Of course there are other factors that may come into play such as improper alignment or not enough tension, but I'm not sure if a wider belt kit will remedy this. This is why I want to wait for everything he has to offer than simply get the slip on sleeve pulley and adjustable sheets.

We'll see. I'd love to let loose doing wheelies and burn outs. Unfortunately, I am running into a battery problem since I've done my shunt mod. I think I'm overusing my Zippy LiFePO4 packs and will have to find a more suitable power source. At about 4Ah, if I put the batteries under heavy load, the voltage will sag under 41V and that causes my 44V LVC, set by my Cycle Analyst, to cut power. If this happens while going up a steep hill, the power cutting in and out will cause the belt to jump teeth. This used to happen when I was at around 6Ah...

You should get that original belt bronzed when it finally packs it in. I have no doubt that you will be the high mileage king on a stock GNG. I am too much like SpeedMD. I like wheelies and burning it from a standstill. Being so well behaved defeats a lot of the purpose of an e-bike for me.

My chain solution is for the secondary side, not the primary. I don't have anything against chain drive. I just think that belt is better for the high speed/low torque primary. Noise is way more of an issue at 6x the drive speed. The secondary has converted speed to torque through reduction and that's where a chain shines. We'll see once I get the large pulley finished which will be very soon. I'm casting other parts in the high impact TASK resin and it's getting to be pretty routine. Once it fully cures it is TOUGH stuff.

IF there is going to be a problem it's that the two pulleys are still too close together for their size and tooth count. When you move pulleys closer the belt angle on the driver gets wider and it disengages teeth. Even though I've added over an inch to the upper sheet length over the original GNG the pulleys are still too close given the diameter of that bigazz 120T. Everything else on my drive, the 20mm wide GT2 belt, the 18 tooth GT2 driver, the ability to properly tension the belt, is overbuilt for the GNG motor. I'm hoping that will make up for the belt angle. If not I'm going to make a ball bearing idler to bring the belt in to the correct spread angle. On my eventual scratch designed mid drive I'll set the pulleys the correct distance apart. We're all still trying to correct for what GNG did and didn't do.

Thanks to all of the people prepaying for parts. I've sold most of the 73mm sheets already and they aren't even plated yet! I am pushing hard on finishing that 120T with freewheel. I'll make lots of noise when I have them available.

Thanks,
Mike

 

[skyungjae]

I can't wait to see your finished products.

 

[E-Norco]

I've been working for weeks developing a #219 secondary drive for the Gen 1 kits. I designed a 3/4" to 11mm adapter so that I could fit a 12 tooth 219 driver on the secondary. I also designed a freewheel to 5 1/4" kart sprocket adapter plate. The 3/4" to 11mm will work with 12T, 13T and 14T 219 sprockets with a 3/4" bore. There is a HUGE range of kart sprockets available from 65T to 93T. A 75T is almost identical in diameter to a 48T 1/2" chain sprocket. The difference is the .3" link pitch. Because of the quality and side plate thickness of good Japanese and German 219 chain they are good up to 15+ horsepower. More than enough for the GNG.

Great idea to use 219 chain LightningRods.

Question:

If i use (48v) a 13t motor pinion with 68t chainwheel with 25h chain the jack shaft will spin = 622RPM (ratio 5,2:1)
then i need a 15t 219chain kart pinion and a 63t kart chainring and the cadence will be 148RPM (ratio 4,1:1) = overall geardown 21,3:1
With a 42t chainring that drives the stock chain to the rear wheel it will be a nice setup to pedal with at 48v.

Is this right?

 

[LightningRods]

Great idea to use 219 chain LightningRods.
If i use (48v) a 13t motor pinion with 68t chainwheel with 25h chain the jack shaft will spin = 622RPM (ratio 5,2:1)
then i need a 15t 219chain kart pinion and a 63t kart chainring and the cadence will be 148RPM (ratio 4,1:1) = overall geardown 21,3:1
With a 42t chainring that drives the stock chain to the rear wheel it will be a nice setup to pedal with at 48v.
Is this right?

Thanks E-Norco. It's a great idea once it works. I am eager to see how it works on the road.

I think your reduction gearing is too high. The primary side is just a bit high at 5.2:1. On the secondary side I would go for a 12T driver and at least a 72 tooth chainring for 6:1. A cadence of 100 is considered fast. I prefer pushing harder at a slower rpm myself. I like 75 to 80 rpm. I am setting my own bike up with 18/120 on the primary for 6.66:1 and 12/80 on the secondary for 6.66:1. This gives an overall of about 44:1 or 75 rpm @ 48 volts.

One of the tricky bits about mid drives is that you have to reduce the motor rpm way down to match the puny human powerband of 0-100 rpm and then gear it back up again to turn that 100 rpm into enough wheel rpm to have the top speed that you want. The reduction gearing and final drive gearing are two totally separate issues. Trying to apply all of the power in a mid drive to high speed is a problem because small rear sprockets can't take the torque without skipping. If you want a high top speed bike you want to use the largest chainwheel driver sprocket that will fit.

 

[LightningRods]

All of the sheet metal parts are back from the platers! I have the following available and shipping right now:

Gen 1.0 adjustable upper primary sheets
Gen 1.1 adjustable upper primary sheets
Screw tensioner for Gen 1.1 primary sheets
68mm adjustable BB sheets
Screw tensioner for 68mm BB sheets
73mm adjustable BB sheets
Screw tensioner for 73mm BB sheets
GNG 4 bolt freewheel to 219 kart sprocket adapter

Cast Polyurethane resin:
18 tooth 20mm wide GT2 slip on driver pulley

Coming next week:
95 tooth 20mm wide driven pulley, no freewheel
120 tooth 20mm wide driven pulley, fits ACS or White Ind five bolt freewheel
3/4" to 11mm sprocket adapter (for fitting 219 driver sprocket on secondary)
12 tooth and 13 tooth 219 driver sprockets

 

[E-Norco]

Thanks E-Norco. It's a great idea once it works. I am eager to see how it works on the road.

I think your reduction gearing is too high. The primary side is just a bit high at 5.2:1. On the secondary side I would go for a 12T driver and at least a 72 tooth chainring for 6:1. A cadence of 100 is considered fast. I prefer pushing harder at a slower rpm myself. I like 75 to 80 rpm. I am setting my own bike up with 18/120 on the primary for 6.66:1 and 12/80 on the secondary for 6.66:1. This gives an overall of about 44:1 or 75 rpm @ 48 volts.

One of the tricky bits about mid drives is that you have to reduce the motor rpm way down to match the puny human powerband of 0-100 rpm and then gear it back up again to turn that 100 rpm into enough wheel rpm to have the top speed that you want. The reduction gearing and final drive gearing are two totally separate issues. Trying to apply all of the power in a mid drive to high speed is a problem because small rear sprockets can't take the torque without skipping. If you want a high top speed bike you want to use the largest chainwheel driver sprocket that will fit.

I have got a 11-34t casette and the biggest fitting chainring will be a 42t.
calculated with 26inch wheel:
1.At 148RPM and 42t chainring the max speed at 34t will be about 22km/h and at 11t about 67km/h
2.At 100RPM and 42t chainring the max Speed at 34t will be about 15km/h and at 11t about 45km/h

If my calculations are right at the first option you can use the gears in the middle of the casette for less chain skipping.
For a good highspeed at 100RPM you'll need a large chainwheel and this will make it hard to move the bike without battery.
The question is if the first reduction like i planned (13t-68t) is good to bring the motor power to the jackshaft?

 

[LightningRods]

I have got a 11-34t casette and the biggest fitting chainring will be a 42t.
calculated with 26inch wheel:
1.At 148RPM and 42t chainring the max speed at 34t will be about 22km/h and at 11t about 67km/h
2.At 100RPM and 42t chainring the max Speed at 34t will be about 15km/h and at 11t about 45km/h

If my calculations are right at the first option you can use the gears in the middle of the casette for less chain skipping.
For a good highspeed at 100RPM you'll need a large chainwheel and this will make it hard to move the bike without battery.
The question is if the first reduction like i planned (13t-68t) is good to bring the motor power to the jackshaft?

Your final drive calculations seem correct. Again what we are dealing with is how puny our own powerband is. We are basically a 250 watt motor with a 100 rpm effective powerband. Even the wimpy little 250 watt motors dictated by the EU standards have a few thousand rpm to play with.

I am going to use my bike in a mix of very hilly urban and country roads and urban bike paths. The only place that I could ride at high speed without pedaling (a huge red flag to the law that you are above the legal power limit) is out on the country roads. It's not very impressive for bragging rights, but 45 kph (almost 30 mph) is pretty good speed on a bicycle.

If top speed is your #1 priority, choose a speed and work backwards for the gearing. Keep in mind that you will not be able to keep up pedaling at 150 rpm. For flat ground high speed runs this is fine. But it will also be true in every gear. So in order to climb a really steep hill you will have to stop pedaling and rely 100% on the motor. This is specifically what I don't want. Even though my 250 watts isn't a huge addition, I don't want to have to stop pedaling up steep hills. How am I going to blow motorists and lycra bikers minds if I can't make them think I'm pedaling my mountain bike 30 mph up a 45 percent grade?

For someone like yourself who doesn't want to completely match the motor to your pedaling, you don't absolutely need the #219 setup. The main advantage would be that you would have the ability to change the driven secondary sprocket to anything between 65T and 93T. So if you were going off roading in a hilly area you could go for a large sprocket to gear down and match the motor to your pedaling. If you then wanted to hit the open road the next day and be able to do 70 kmh, you could just swap out the driven sprocket for a smaller one. 1/2" bicycle chainwheels will give you the high speed options, but not the low off road gearing. There just isn't room for a 75 tooth 1/2" sprocket.

 

[Denisesewa]

I love cruising by traffic pedaling at about 50 rpm and doing 35 mph uphill, blows people's minds even though my pedaling does absolutly nothing, it also keeps the cops from taking notice as long as I am cruising at normal bicycle speeds, I sometimes pedal backwards just to get people really thinking .
Lighteningrods, you have gone above and beyound in your quest to legitimise the GNG, very cool, Now get your bike built !
On another note, I ditched the Super-V chassis on the second build and started over building another " trials" type bike , just didnt like the geometry of the Super-V, the new bike is much like the first and has a couple hundred miles of hard offroad use without issue so far, just for fun I cranked up the Lyen controller to 45 amps at 14S , couldnt really keep the front wheel on the ground when I needed to though, still it was a blast but the battery duration was so short the way I ride that I put it back to 36 amps.
The Bike works great for hard trail riding and I just pop out the seat for serious trials riding.
I still have to build the carbon fiber bodywork and do paint but at least the mold is made ( which I am using as bodywork temporarily), but have been too busy with camping, fishing riding and a 2 month kitesurfing trip that I have been putting it off.
Second build in progress >>


First build finished >>


"D"

 

[LightningRods]

Great to see you on the GNG thread again Denisesewa! Great looking builds as always. Next on my Skills Acquisition List is forming and laying up panels. Carbon fiber is such great looking material.

My bike is very close to being on the road. I know I've gone at this kind of weird, re-engineering the whole kit before building my bike, but I HATE shoddy junk that doesn't work properly. I have just a couple of missing parts to get made and then I finally get to have the other kind of fun you can have with an e-bike.

Don't be a stranger. We need you on here.

 

[Secret1511]

Here is my chain mod.
I keep breaking belts so let's hope this is the solution
I used the freewheel 65T that bzhwindtalker came up with. The small spocket is a 11T. Makes a bit noise.
Question: I want 1 freewheel in the system so the small one has to go. What is the best sprocket to go for?

 

[LightningRods]

Here is my chain mod.
I keep breaking belts so let's hope this is the solution
I used the freewheel 65T that bzhwindtalker came up with. The small spocket is a 11T. Makes a bit noise.
Question: I want 1 freewheel in the system so the small one has to go. What is the best sprocket to go for?

My opinion would be 12 tooth. If you can't find anything with an 11mm bore, look for a 3/4" bore. I'm making a 3/4" to 11mm adapter. I'm going to make 12T and 13T #219 drivers ready to bolt on. If enough people prefer staying with 1/2" bicycle chain I'll make 12T and 13T 1/2" drivers with an 11mm bore as well.

 

[Secret1511]

Ok i will go for the regular chain. I don't know what type ot is.
Is the 11t on the first drive a good choise? Is a 12t less noisy?