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

I picked up my new adjustable primary sheets for the GNG Gen. 1.1 today. The first production run is available now.

G1.1_product.jpg


In addition to providing better water and grime resistance the new jackshaft makes the entire primary assembly stronger and more rigid. I've added a second through bolt and two steel spacer tubes for even more strength. The final improvement is that I've added an additional 1/2" of length to the adjustment slide to create a better belt angle at the driver pulley and to allow for the use of up to 120 tooth driven pulleys with 18, 19 or 20 tooth drivers.

Coming very soon is my all new belt primary drive. I am changing the belt type to a more performance oriented belt, increasing the width of the belt from 15mm to 25mm and adding more teeth and a proper profile to the driver pulley. I estimate that the new drive will have about 4x the power handling capacity of the original GNG primary.

Many thanks to forum member hillyterrain for loaning me his GNG Gen. 1.1 drive for prototyping.

-Mike
 
Thanks guys! These new sheets will bolt right onto a Gen 1.0 kit because the motor hasn't changed. Even the jackshaft inside the tube is the same one with the same pulley and freewheel sprocket on it. The diameter of the end of the jackshaft tube is smaller than the diameter of the old outside bearing blocks. So if you want to run these new sheets you will also have to get the new 'waterproof' jackshaft from GNG.
 
LightningRods said:
Coming very soon is my all new belt primary drive. I am changing the belt type to a more performance oriented belt, increasing the width of the belt from 15mm to 25mm and adding more teeth and a proper profile to the driver pulley.
Click to expand...
Love your work Mike. :mrgreen:
How soon and is it a bolt on mod?

...
 
I don't my left crank will be able to clear a 25mm belt
Click to expand...

Good point skyungjae. Mine ends up just clearing the jack shaft end on the secondary side using the 122mm bb. May end up shortening the shaft a few threads. Stock belt pulley hub is gone in this build but would be a issue with going this narrow. Overall I am very happy with the much more compact and closer to center the chain lines are ending up on the bike. May be able to sneak in a support bearing but it is very tight. :oops:
 
I'm still waiting for the GT2 pulley stock to arrive so the 25mm width isn't set in stone. With the stock GNG spindle and crank there is over 1" (25.4mm) of clearance between the stock pulley and the inside of the crank arm. The particular company that I am ordering from offers GT2 in either 15mm or 25mm. I'm up for the extra width for when I start cranking up the wattage. After all of the headaches with this drive I want to go overkill.

I'm also planning on offering a nicely finished 18T HTD driver pulley in 15mm width. This will be for sane people who use their GNGs as commuter bikes and just want decent belt life at stock voltage levels.

You #25 primary chain guys are covered four ways from Friday and don't need my help. Don't heckle the belt customers. :mrgreen:
 
rp3 said:
Love your work Mike. :mrgreen:
How soon and is it a bolt on mod?
...
Click to expand...

Thanks Mate! My plan is for this to be a bolt on mod but it will probably involve pulling the motor spindle. I've ordered replacement spindles from China that are longer on the output than the GNG pulley. I'm going to machine these down to the 12mm standard that spinningmagnets has been promoting and then likewise make the bore of the GT2 pulley 12mm. The motor spindle and pulley will be available separately.

I'm going to push this forward as fast as I can. The weather is getting nice here in Western Oregon and I want to get my e-bike out on the roads and trails.
 
spinningmagnets said:
A smaller inner chainring on the bottom bracket would help relieve this a bit and give me a higher top speed, right?
Click to expand...

Go bigger on the inner chainring. If the 38T and 44T stock chainrings can have their locations swapped...I would put the 44T on the inner position, and the 38T on the outer. Then, I would find the biggest chainring I could fit onto the frame, and epoxy/bolt it to the side of the 38T (52T-60T?).

If the resulting ratio is too fast (hurting the hill-climbing ability), then you can use a larger gear on the rear. This is good because the more teeth that are engaged with the chain at the rear, the less stress is applied to each individual link/tooth.
Click to expand...
hello members....

a thankyou to spiningmagnets for this simple mod

i had a shimano 52t...5 bolt...chainring in my bike parts box......the pcd/bcd was the same as the 38t....5x4mm hole pcd......

so i drilled the 4mm holes in the 38t chainring to 10mm holes.....now the sprocket mounting hardware would fit.....

a 30min mod...

i hope that the pics show what i mean...IMG_0245 (640x480).jpgIMG_0243 (640x480).jpg
 
hello spinningmagnets....

no...not yet...my frame is at the platers till next tues/wens...

i did a bit of a mock-up beforehand and i had clearance on my chainstays....

going 3mm inboard with the 52t chainring has given me a better alignement to the 12t jackshaft sprocket......

for my set-up i can't see any issues....all looks good.
 
christerljung said:
I run a similar configuration on my GNG-kona Stinky. (48/48) Can pedal normaly at 70kph and still climb in slowmotion. 8)
Click to expand...
hello christerljung....

i have been reading you posts....very impressive results.....you're earlier posts settled my purchase of this kit....

i'm at the bottom of the learning curve so i'm only playing with 48v......i'll sort out all running issues at this voltage....

latter on i can look at better batteries...higher voltages ect.....should i wish to go that way....

if i zoomed around my town at 70km.....and the boys in blue got me .......it would cost me the best part of $2,000 dollars....minimum......
 
tri-lobe said:
christerljung said:
I run a similar configuration on my GNG-kona Stinky. (48/48) Can pedal normaly at 70kph and still climb in slowmotion. 8)
Click to expand...
hello christerljung....

i have been reading you posts....very impressive results.....you're earlier posts settled my purchase of this kit....

i'm at the bottom of the learning curve so i'm only playing with 48v......i'll sort out all running issues at this voltage....

latter on i can look at better batteries...higher voltages ect.....should i wish to go that way....

if i zoomed around my town at 70km.....and the boys in blue got me .......it would cost me the best part of $2,000 dollars....minimum......
Click to expand...

It's interesting... just when I think I'm done tinkering with the kit, there's more I want to do with it. As soon as there is a reversible chain drive option (probably never going to happen), I'm probably going to start tinkering with higher voltages as well. Not looking forward to having to re-wire everything with heavier gauge wire though. I should have thought ahead instead of thinking, "12ga will be fine for 20A." :|
 
I read earlier in this thread that with the stock gear ratio and 50V the cadence might be too fast to pedal comfortably and that 36V might be better, but that the stock controller won't play along because of the low voltage cutoff.

I'm not worried about top speed but about torque, I'm climbing really long really steep hills, so my current understanding is higher Voltage means higher top speed, higher amperage means more torque. Hence I'm considering going less volts and higher amps, how many amps can the GNG handle? Which controller should I get for that?

I currently have two 6s 30C HK LiPo, I guess there is no good way to reuse them for a 36V setup ..is 22V to small for usable hill climbing? Any ideas? Thanks for you input!
 
I'm climbing really long really steep hills, so my current understanding is higher Voltage means higher top speed, higher amperage means more torque.
Click to expand...

In general, your above statement is correct, but I don't think it's practical to try to shove enough amps at the lower voltages without larger wires, etc.

I put a stock 48V GNG on a bike with big 29" wheels and worried a little about it being able to climb good. The road coming up to my house has sections of 15% grade and my Path trike pulls the hill okay in third gear. I gave that bike to a sister that has steeper and longer hills than I have and when we went for a test ride, her on the GNG equipped bike and me on my trike, I was going up hill full throttle in first gear and she buzzed ahead and out of site. She was literally running circles around me, as she came back a couple of times to check on my progress. Neither the motor nor the controller heated up at all on the GNG unit.

So my guess is this unit would handle most San Francisco hills with ease, particularly if mounted on a bike with 26" wheels or less.

Good luck with whatever you decide to do.
 
Most GNG owners who have experimented have posted that they are fairly happy at amperages up to 30A. Above that, there seems to be excessive heat generated faster than this motor can shed it. Of course it depends on how often and how long you are feeding it 30A peaks. Just once in a while means the motor has time to shed the heat while you are just cruising.

A guy who has a very long uphill and has heavy cargo in a headwind may overheat at 25A continuous...and another guy who rarely hits his max might get away with the higher performance of 35A occasional peaks...

Perhaps add a temp sensor and keep an eye on it, but I'd want 30A available with this kit, based on several reports...
 
Rather than opening a new thread i wanted to post on a couple of issues pertinent to this thread:

a) tensioning the secondary drive chain - i have discovered it is straightforward to do this by shiming out the space between the hoseclamp/jubileeclip mont on the motor and the down tube of the frame - currently i have a small block of wood in there - it also occurs to me that it would be fairly easy to fashion an aluminium mount/clamp that wouldact as both a spacer and a frame mount which would do away with the jubilee clip and could be designed as a tensioner too

b) rounding off the teeth on the razor sharp primary drive motor output shaft - i got a round chainsaw file broke it in bits and put a bit in an electric drill , pulled the washer /belt retainer off the end of the shaft and then used the file in the drill to round off the sharp edges on the teeth - a variety of different file diameters will facilitate a 'proper' rounding off

i would be interested to know if others have discovered the same solutions and if so if there are any disadvantages i have missed
 
An update on my resin cast pulleys.
Before I make a housing to cover the new pulleys and belt I have been making a few test runs. So far it’s looking promising the belt has not slipped and the pulleys have not given out yet, but I have only done a few miles on the road and tracks. The large sleeve pulley is 107T and the motor sleeve pulley 18T, as I describe in an earlier post I have gone up to a 20mm belt.

I added some guide bearings on either side of the drive pulley to engage a couple more teeth as the large pulley gives a rather shallow angle for the belt onto the motor pulley. This has introduced a few extra watts of ‘waste power’; but not as much as the original GNG belt pulley arrangement.

I will do a few more test miles in the next few days and decide if I will continue with the belt pulley setup, or go down the #25 chain and sprocket arrangement. I have a spare GNG1 now so it means that one of them will have to have the motor drive shaft turned down for the sprocket, if I decide the belt is not reliable.

8672329654_50267404ce_c.jpg


8672333970_0f40778d61_c.jpg
 
For those of y'all running a pair of 6S liPos for 44v. What are you setting your LVC's at? Is the 36v LVC on the controller adequate?

I'm considering picking up a pair of the Turnigy 8Ah 6S batteries.
 
tri-lobe said:
spinningmagnets said:
A smaller inner chainring on the bottom bracket would help relieve this a bit and give me a higher top speed, right?
Click to expand...

Go bigger on the inner chainring. If the 38T and 44T stock chainrings can have their locations swapped...I would put the 44T on the inner position, and the 38T on the outer. Then, I would find the biggest chainring I could fit onto the frame, and epoxy/bolt it to the side of the 38T (52T-60T?).

If the resulting ratio is too fast (hurting the hill-climbing ability), then you can use a larger gear on the rear. This is good because the more teeth that are engaged with the chain at the rear, the less stress is applied to each individual link/tooth.
Click to expand...
hello members....

a thankyou to spiningmagnets for this simple mod

i had a shimano 52t...5 bolt...chainring in my bike parts box......the pcd/bcd was the same as the 38t....5x4mm hole pcd......

so i drilled the 4mm holes in the 38t chainring to 10mm holes.....now the sprocket mounting hardware would fit.....

a 30min mod...

i hope that the pics show what i mean...
Click to expand...
Great idea! just picked up a similar 52t chainring to do this mod.

I've done an 11:80 reduction on my primary and at 14s the cadence of the motor is much closer to that of my legs. Hopefully with this mod it will be even better!
 
hi

I just started working on a gng chain drive conversion, i would like to drive it with lower voltage 36V but some higher amp peaks up to 50 A i just read about putting bigger wires on the kit.

are there any photos on changing the wires because I'm not sure where and how they are welded to the inductor.

thanks for tips and help

notger
 
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