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

[speedmd]

I dont get this graph, seems like the GNG is made for more than 25amp battery current...
or in other words, it's just made for 36Volts or geared horribly too fast. The motor never spins in a region where it can make use of its back EMF, even at 36Volts.
This way a lot of energy is wasted due very high switching loss all the time.

http://www.peakeff.com/GraphKIR.asp...s=True&apc=False&all=False&title=GNG+Drive+V1

Ordered my gen 1 kit and planning to swap out to the #25 chain drive on the primary side. 12s4p 20ah lipo pack and 700c x 32mm wheel/tires. Hard pack/ road /country-suburban use. Looking at the chart, it looks like I should be looking for much more gear reduction to the crank than stock. With the #25 sprockets, possibly 66/11 or 72/12 or even 75/12 tooth reduction with the stock secondary ratios to match a good spinning pedaling pace.

 

[Denisesewa]

[q
Ordered my gen 1 kit and planning to swap out to the #25 chain drive on the primary side. 12s4p 20ah lipo pack and 700c x 32mm wheel/tires. Hard pack/ road /country-suburban use. Looking at the chart, it looks like I should be looking for much more gear reduction to the crank than stock. With the #25 sprockets, possibly 66/11 or 72/12 or even 75/12 tooth reduction with the stock secondary ratios to match a good spinning pedaling pace.

I would recommend the larger driven gear rather than anything under 12 tooth for the drive gear, even with 12 the wrap and tooth engagement is pretty minimal although I havnt had a problem running 12, I have an 11 and a 13 you are welcome to if you need them.\
"D"

 

[speedmd]

Thanks. You still running a 12/65? Standard final? 14s? How is it to pedal with?

 

[Denisesewa]

Thanks. You still running a 12/65? Standard final? 14s? How is it to pedal with?

Yep, still 12/65, final is 34 /28/22 , I dont pedal much, havnt found too much the bike needs pedal assist with but its not pleasent when I do pedal, 12 / 75 or 80 would be better but you'll need Lightingrods sheets to go that big.

 

[LightningRods]

Picked up a new bike and finally put it all together. The adjustable sheets work great!

Sweet looking bike, Bee! That's going to be a blast to tool around on! I wish I could come up with a universal battery box that would fit a wide range of full suspension bikes. There are so many shock and frame layouts that it makes it tough.

 

[speedmd]

Yep, still 12/65, final is 34 /28/22 , I dont pedal much, havnt found too much the bike needs pedal assist with but its not pleasent when I do pedal, 12 / 75 or 80 would be better but you'll need Lightingrods sheets to go that big.

Found a nice alloy 72 tooth sprocket that may be a good stating place. 12 tooth on the motor. 5.714:1 stock vs 6:1. Stock final for starters. If I can fit two wheels simply I am shooting for 50/34 or 48/32 tooth rings in the crank long term to be able to get a bit more speed on the road down hills.

 

[LightningRods]

I'm still working on the belt primary solution. I've ordered both a 95T and a 120T driven pulley that should be here on Monday. I'm waiting for a bid on a laser cut 18T sleeve adaptor for the drive pulley. 18/95 is 5.28:1, just a bit worse reduction than stock (but with way better tooth engagement). 18/120 is 6.66:1. If that 120T is a decent quality pulley it will solve all of the belt problems. It's only $29.95 at Electric Scooter Parts.

https://cart.electricscooterparts.com/ProductDetails.asp?ProductCode=SPR-COG120.

Can't beat the price if it's any good. We'll see.

 

[speedmd]

Is the center thread right hand or left hand on the large stock pulley. Can not tell from the pictures.

 

[LightningRods]

Is the center thread right hand or left hand on the large stock pulley. Can not tell from the pictures.

It appears to be a righty-tighty.

 

[Denisesewa]

Is the center thread right hand or left hand on the large stock pulley. Can not tell from the pictures.

it is Right, standard freewheel threads

 

[Miles]

It's only $29.95 at Electric Scooter Parts.

https://cart.electricscooterparts.com/ProductDetails.asp?ProductCode=SPR-COG120.

Can't beat the price if it's any good. We'll see.

Well, you can..... It's $15-00 at TNC.... Curious that it says TNC have discontinued it, on the ESP site............

http://tncscooters.com/index.php?route=product/category&path=63_94

 

[rp3]

I had to get a new bike for the gng. Needed some rear suspension,only a cheapy but it'll do for now.

 

[gorach]

I was wondering what the technical difficulties would be in swapping the primary drive pulleys with appropriately sized cogwheels? If there was a strut supporting the outboard ends of the two shafts, and some kind of lubrication, wouldn't this be a great way of going backwards at high speed???

 

[bee]

I can't get the belt tight enough so that it doesn't skip teeth on the small pulley when hammering the throttle for power wheelies. Because of the slightly imperfect wobble of the large pulley, the belt will be tight, and then 1/4 turn later it gets some slop. My plan is to abuse the hell out of this bike, I'd like to wheelie up curbs and commute up and over the mountain I normally have to drive around, so I might be doing the chain conversion sooner than later. First I'm going to try 3d printing some small pulleys to see how they hold up though. Replacing the 18t pulley with a 22t will reduce the reduction ratio, giving me less torque but more high speed, correct?

 

[speedmd]

Is the center thread right hand or left hand on the large stock pulley. Can not tell from the pictures.

it is Right, standard freewheel threads

Locks against the left side shoulder of hub. The final side is also standard right hand thread?

 

[gorach]

Cogs instead of sprockets instead of pulleys anyone?

 

[spinningmagnets]

Gorach, with enough money and time, just about anything could be done. Staton-inc sells a $200-ish gearbox for their gasoline and electric bicycle drive kits. You could couple a motor directly to the gearbox input shaft. Like the second pic below, you could make your own box to install purchased gears, if you have the tools. Water-proof the motor with a proven conformal coating, fill 1/3rd with ATF for lubrication and cooling and then test to see what power levels you could achieve.

The benefit of the #25 chain primary is the $40 price for the parts, allowing 3,000W. The benefit of the belted primary would be quieter operation. The gearbox would be more expensive than chain, and noisier than the belt, but it is certainly doable.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=43062&start=75#p638179

 

[Denisesewa]

Cogs instead of sprockets instead of pulleys anyone?

Way too much work for too little gain in my opinion , $30 worth of chain and sprockets and a couple hours work to fit them ( which also eliminates any runout), this has proven to be reliable up to 45 amps/ 72 volts ( Christers and others bikes), quiet when coupled with lightingrods adjustable sheets ,replacement parts are off the shelf items , its easy to do , easy to change ratios and in keeping with the spirit of the kit, ( quick, cheap and dirty 8) ).
I understand the desire to keep a belt primary and for some its a matter of a fun project and having the tenacity to make an idea work ( Applause ! ) but for me it just isnt worth the headaches , trying to fabricate the parts to do a gearbox ( which must be precise with lash tolerances to the thousands of an inch and sealed for lubrication) would be expensive and problematic.
I've beaten the snot out of my setup and its working great.

On a side note, I took my bike to visit a freind who is a supperb trials rider, within 5 minutes of playing around on it he wheeled it around a city block without setting the front wheel down, sure wish I would of had a means to video that! ( Dang young-uns )

 

[LightningRods]

I understand the desire to keep a belt primary and for some its a matter of a fun project and having the tenacity to make an idea work

Thanks for not just coming out and calling me mule stubborn.

I can't help it. I just think the belt drive is sexier. It may be the supercharger drive connection that another poster mentioned.

 

[speedmd]

http://www.youtube.com/watch?v=l_1TJQIMdEg

Some good riding on the gassers. Amazing stuff.

Was thinking 10- 15kw needed maybe, for suitable e drive in much the same/ lighter chassis?

 

[gorach]

thankyou for your kind replies denis and spinningmagnets. I do like the gearbox/reducer units on both the aprilla and tonaro, quiet, efficient and overvoltable.
The gas trials video there reminded me of the Gen2 at 44v and 30amps :lol: the jerky unicycle effect is a bit excessive for me even on a full suspension bike. Dread to think how the gng1 at 72v & 45amps takes off, flipping madness I say!

 

[LightningRods]

flipping madness I say!

Literally!

 

[LightningRods]

If you have some 12V car batteries at your disposal you can make a series battery pack to do some bench testing. The only thing that's seriously wrong with lead acid is that it's bulky and heavy. For bench testing they're actually great. 12+12+12+12=48. I may try to round up a couple more and see what 72 volts in a GNG sounds like. Amp draw was super low because of low load, around 2 amps. I guesstimate that the amp capacity of this lead acid array is at least 100 amps. It would be interesting to load the motor in some way and see how it handles the heavy load + high amps.

If any viewers are unclear as to how series wiring works this video shows it pretty clearly. Positive to negative seems wrong at first, but any time you loaded up a flashlight with C cell batteries you were stacking batteries plus to minus in series for more voltage.

http://youtu.be/r3lTO2NUBPQ

 

[Denisesewa]

It would be interesting to load the motor in some way .

Riding it would do just that.
You ought get that puppy mounted on a bike, I promise its more fun than bench testing

 

[LightningRods]

It would be interesting to load the motor in some way .

Riding it would do just that.
You ought get that puppy mounted on a bike, I promise its more fun than bench testing

LOL. Busted! Today was actually a decent weather day here in Oregon and it did get me wanting to be out on a bike. I'm up against both battery pack purchase and bike purchase right now. I should have charged more for the adjustable sheets! :lol: