third GNG - The Kona Stinky

Joined
Aug 22, 2012
Messages
265
Location
Falun, Sweden
I couldn´t resist this little nimble thing. Got it for for 270$
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GNG will be ordered through aliexpress.
 
Yup. I'm just waiting for one to show up in a "for sale" section in my area :arrow: NICE FIND :!:

Hey is that a 69er? 26" in rear 29" in front :?:
 
Nice find. Might be my eyes, but it looks like the rear brake rotor is larger then the front.
 
Very nice, watching this one with interest.

D
 
On my build, the inner chain ring was already quite close to the hex bolts going through the motor mount bracket. Hopefully you don't run into any clearance issues there.
 
48T is nice! but for gearing it right for human speed, you would need 60-64T @ 44.4V/12s lipo ;)

Edit: Ok, that's BS, since I see you install a larger final drive chainring? Why do you do that?
Since it seems like you dont pedal anyway, it should even LOWER both torque and efficiency?!?! :shock: :shock:

for your needs a 36T final drive chainring would fit a lot better, you still use your 74V/20s lipo battery, do you?
 
OK is see you even want to use 24s lipo. That absolutely makes no sense at all. You will waste most energy to eddy current parasitic loss. The motor is made for 72V MAX for a reason.

If you want more speed, then you need more current, since your setup never runs into the good efficiency region.

I would try 12s lipo @ 60amps battery current limit.

But now that you own this setup: It would help a lot, if you could measure no-load current @24s lipo. this way we could see how much eddy current loss rises in fact!
 
I´m aware of the eddiecurrent problem. It´s easy to reroute the wiring for 72v if 88v seems bad.
This is a realworld test is to see if these "eddies" will be a obvius loss i accelleration at higher rpm:s. Or maybe it isn´t?
Even if there is a loss it would be nice to have a motor able to pull, both at low trail climbing speed (no losses and good torque, we already now that the GNG has massive torque), and HIGH speed ability. That´s what i meant in the GNG-thread, where you showed the diagrams. At first i didn´t realize that the diagram was without eddies.
It´s always better to make watts out of more volts. More amps gives more heat, thicker cables, thicker windings and so on. But ofcourse high voltage also got it´s problems.

Tonight i did finish the back drivetrain. A cheap Acera mesh will do the shifting. I liked the stable and big cage-wheels of this derailleur. But the angle of the shifting-cable is horrible. Not for off-road use. :?
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crossbreak said:
48T is nice! but for gearing it right for human speed, you would need 60-64T @ 44.4V/12s lipo ;)

Edit: Ok, that's BS, since I see you install a larger final drive chainring? Why do you do that?
Since it seems like you dont pedal anyway, it should even LOWER both torque and efficiency?!?! :shock: :shock:

for your needs a 36T final drive chainring would fit a lot better, you still use your 74V/20s lipo battery, do you?
Since the first reduction in this setup now is a 12/72 chain-kit, i got 6:1 reduction.
The 72v setup did never need to use the 20 - 34 coggs in the cassette, so thats why i want 48t finaldrive chainring. This will also help pedal cadense at >50kph. Ideally the chain would almost never need to use the smallest gears in the cassette, since these will be worn out too fast.
48t maybe was overkill, 46t would been more reasonable. My dream is to test this setup on the sea-ice soon. The first GNG above 100kph? :shock: :shock:
 
Great that you did not fix your battery voltage. Can you measure no-load current at 88.8V for us. I'm waiting keen to see this figure!

The graph below just looks too good to be true ;)

made some calcs about your setup. Seems like 100 km/h is out of range. Power is just too low. Needs a second GNG :twisted:
 

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crossbreak said:
Great that you did not fix your battery voltage. Can you measure no-load current at 88.8V for us. I'm waiting keen to see this figure!

The graph below just looks too good to be true ;)

made some calcs about your setup. Seems like 100 km/h is out of range. Power is just too low. Needs a second GNG :twisted:

Even at 88 Kph with your graph his ebike is faster than a Stealth Bomber :shock: :shock: :D
Black Arrow
 
Finally i got it out on a little test.
I´m still on 18S 72 volt, need to re-program the controller before we fly on 88volt.
Anyway, i had some fun before the motorpulley was sliding on the shaft. Never got those setscrews in good thgtened way, it´s some strange size of the screw that i didn´t have the right tool for.
Was afraid that the gearing with 48t final drive would be too high, but in the big 34 cassette ring it felt really nice for some lounge-riding. Never had it in the high speed gears since i had to walk it home when the motorpulley said: stop.
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I had a brutal ride yesterday. Got the controller configured for 24s 95A phase current and 65A rated. Also added power levels. I never got to open field to try full throttle at max power beacuse the chain jumped and destroyed the 52 chainring. The chain jumped at no power but a little jump when i was in the lowest gear (11t). Probably my homemade chaingudie wasn´t tight enough. Power was insanely brutal. CA was reading 100volt and 50 amps. It felt totally out of control. Gonna look for the magura/denisesewa throttle setup. And of course a professionally made chainguide.
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Made some more tests today.
Added a mud and waterprotection coat. Really ugly but all things (battery, motor, chains, frewheels and gears) are totally protected.
The freewheel was in the beginning of unscrewing itself so i added a little welddot to it.
The phase current was set down to 30A ,was 95A before. I just wanted to feel the difference.
30A Feels almost soft and lame. But there is just enough power to make a wheelie.
95A Is furious.
40% power in lowest power mode(out of three) gives ultra-slow creeping speed. Really stealthy and fun in the woods.
The gearing with 12/72 ,12/48 and 48/ 11-34 is absolutely great.
Another thing to notice is how silent the #25 first reduction is. It's maybe even more silent than the original belt.
The Kona original rockshocks fork is awful, probably needs a rebuild.
Kona frame feels nice for slow trail. Good low gravity balance with this setup. A little nervous in higher speed.
No possibillity to try the topspeed yet. 8)
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