GNG Drive Gen2

thank you for taking the time to reply Cyclebutt & d8veh,

Given that I have only 1 hill that stresses my 350W BPM, I guess that I'll just stick with it + the lyen controller which'll feed it up to 1400W. It's great to get feedback from folks who've actually tried both :)

I love overtaking the lycra boys on their £3000 whippet-like bikes, I know it's childish but it makes me happy :twisted:
 
johnamon said:
thank you for taking the time to reply Cyclebutt & d8veh,

Given that I have only 1 hill that stresses my 350W BPM, I guess that I'll just stick with it + the lyen controller which'll feed it up to 1400W. It's great to get feedback from folks who've actually tried both :)

I love overtaking the lycra boys on their £3000 whippet-like bikes, I know it's childish but it makes me happy :twisted:
Click to expand...
Whether they admit it or not, all ebike people get a kick out running the "lycra" set. And the more stealthy we are, the better....HA!

cheers!
 
Have replaced the stock controller(20amps) for the gen2 kit with a K123 controller. The bike is now running on 12s lipo at up to 33amps. Naturally the bike is now extremely responsive and quick but I am concerned about the narrow guage of the motors phase wires - 18 or 20awg. Havn't ridden this setup far but suspect this current level is way more than the motor will cope with for long, has anyone tried the Gen2 at these power settings yet?
 
How long a run of wire are we talking. 20 gauge Cu wire at 4 feet will have a 3 percent voltage drop with 35 amps/48v. The Old timers in the shop always used a rule of staying below 2% drop to keep things from getting too hot. The 18 gauge will be under 2% drop at 4 feet length which going by their rule will still warm up but should give reasonable service / duty cycle. A good Calculator link. http://www.powerstream.com/Wire_Size.htm
 
Many thanks for the link and your advice speedmd. The phase wires are about 3 feet at 18gauge which on the table gave 2.5% voltage drop which I guess is right on the brink. 30 amps peak is one thing but normal operating current prob more like 10amps and thus within your 2% guideline. Will keep it as is for the moment with an eye on the motor/phase-wire temperature. Appreciate your response, thankyou.
 
Thanks Gorach for the kind words. Honestly, it brings back lots of good memories of my first job getting mentored by the old guys. Some had great stories of how the early Stanley, Stienmetz companies/groups would conduct the daily business of developing better dynamos /generators. They worked only with rectangular copper most recently. All are long gone now.

I never questioned the 2% guide line, but would look to add cooling if losses go above it for long. They built things to last a life time. I am sure some other members can share some insight as to how close to the edge this may be from a thermodynamic view. Look forward to your temperature measurements /duty cycle analysis.

cheers
 
Perhaps by "motor phase wires" you mean the connection wires to the motor? The phase wires internal to the motor (windings) will be the same aggregate gauge or less and will be in a far worse situation with regard to heat dissipation. Motor coils are usually run at a greater load than the normal cable ratings for the same gauge, though. Lacking an accurate specification for the motor, the only way to determine the maximum sustainable amp rating is to monitor the temperature. Without any information to the contrary, you'll have to assume that the magnet temperature shouldn't be allowed to exceed 80 deg. C. and the windings around 120 deg. C.
 
I purchased a GNG Gen 2 a couple of weeks ago and it arrived very quickly, but i am having problems with the freewheel crank assembly. When mounted on the BB the crank wheel oscillates away from and to the frame when rotated. It does this if i rotate the crank gear by hand with the freewhel open ( which i think rules out a bent bb), and if i rotate the crank arm forward or backward with the freewheel in the open or locked postion. I have stripped it down and inspected the bearings etc and it looks ok to me , everything is tight....actually the freewheel is too tight once the crank bolt that secures the crank arm is on ... i guess there is not enough space for it to move in its oscillation sideways.....does anybody know whats going on here? here are two short vids[youtube]http://www.youtube.com/watch?v=8IGq5WAv6Jk[/youtube],[youtube] http://youtu.be/FU38wbi4pL4[/youtube]

I am also not to impressed by the fit of the inner bearing..it seems pretty loose to me ....if i was putting it on a car i would have a very big question mark about its safety.
 
I believe the wobble in your chainring would be called "axial runout".

Take the chainring off and lay it on a perfectly flat surface. If the chainring is not bent, then I would suspect the joint between the crank-arm and spindle-shaft. Either one part or the other is bad...perhaps both.

If run this way, I believe your run-out is bad enough the chain will "throw itself off the cliff" under speed.
 
Also check if the crank arm is fully seated on the bottom bracket spindle. The square shaft interface may be defective causing the runout noted.
 
Thanks spinning magnets and db baker . I'm rulling out the connection b/w the crank arm and spindle because when I rotate the freewheel with the crank arm and spindle stationary I get movement through the crank arm .... To and away from the frame .The bolt that attaches the crank arm to the axel cannot be tightened otherwise the freewheel just doesn't move .......when it is only tight enough to allow movement I get this sideways movement through the crank arm ............ So to be clear - axel play when the crank is spun both ways , same movement on horizontal plane through the crank arm when the freewheel is spun without axel moving ......the chain gear I will lay it flat but I'm pretty sure it is ......and I agree I think it will be throwing chains constantly ! Thanks for your suggestions I will look at all of the parts again .
 
I saw the video. Yeouch. Talk about disynchronicity. If you can't figure it out, try your LBS. I'm sure they are all too familiar with the nether regions of your steed.
 
ALSpong, I hate to suggest buying a part when there is no certain evidence it will fix the problem, but...you might try a wider BB-shaft. Staton-inc and SickBikeParts might have those (among others...). I believe a wider BB-shaft would allow you to tighten the crank-arm down tighter without the freewheel hitting the clearance problem, but even this may not fix your problem. Just a thought...
 
Thanks everyone for your help .... I have solved this problem but I wouldn't have done so without the support and flow of ideas ........ I was rechecking everything and found I could run the crank arm and flywheel together on the bb ... Same problem - but success because It seemed the issue was the thread holding the flywheel and crank arm together ... I pulled the two apart today and found I had cross threaded the crank arm onto the freewheel ... I'm not sure how I did this ... When I initially installed the crank arm I did so without force and with ease .. Anyways no more axial play .. There is some movement upwards suggesting a high point / not centred , but this is trivial compared to the initial problem ...... Pheeew ... I work on cars a lot and I've never encountered anything like this before .... I guess it's onły possible when one hard metal ( freewheel) and soft metal meet (crank)
 
It looks to me like the crank arm is cross-threaded in the free-wheel.
Edit: Sorry, I didn't see your last post. I'll try and be quicker next time.
 
Just a heads up to everyone, got my GNG v2 about 2 months ago - haven't had time until now to install it and play with it. While it still is not installed, I am testing no load kV output of motor at 9t and also using 2 phase lines and EagleTree v3 logger I am able to measure no load of the internal inrunner.

I will be testing on 10S (37v) and 12S (44.4) using the stock controller and setup then moving on to check 14S (51.8), 15S (55.5) which I've tested with success on the stock controller of the Gen1 system and then moving up to 16S, 18S, 20S and finally 24S all using a modified EB806 and EB206 (old and new infineons) before installing on a 20" 2012 Downtube Nova folding bike.

Results will be posted by tommorow and install will commence tonight (unless my new HobGoblin or Trek Fuel EX8 Full Suspension bikes and my new Recumpence Dual Davinci drive arrive and distract me with a new build)

Upon first inspection, or rather item glaring at me is the use of a chain tensioner... based on the design of the motor mount and flanging I am dissappointed that one is even required, should be a sliding adjustment or a link and half link?

One other issue is with the freewheeling crankset - unlike Gen1 GNG the Gen2 has 38t for both motor drive and pedal input. That means final ratio from motor output 9T to the Crankset 38T is a reduction of just 4.22:1 but the bigger issue is the normal chainring (for pedal input on the 7 speed Nova) is 46 Tooth which is a drastic reduction in potential input cadence (in the wrong direction) taking what was an up gearing of 5.11:1 to 4.22:1 which means a comfortable cadence of about 90 (comfortable cadence to me) which used to produce a top speed (flats) with a 160 lb rider to a maximum of 460 RPM or 27 mph down to 380 RPM or 22.5 MPH.

I will attempt to locate a replacement 4 bolt crank for pedal input with 46T to keep proper pedal cadence and speeds.

More to come, hope it helps...

-Mike
 
More shenanigans ... Not sure if this related to my previous post but the freewheel bearings blew out ..... Anyways thought I'd try to get a local replacement and have found the thread on the replacement freewheel is different to the gng. Has anybody found this , do freewheels generally come with different internal threads ... Love to get my bike going ASAP and not have to wait for 3weeks for parts to arrive...... I'm considering having the crank thread recut to fit the new freewheel .. It's a cheapy .. Dicko or something like that
 
mwkeefer said:
Just a heads up to everyone, got my GNG v2 about 2 months ago - haven't had time until now to install it and play with it. While it still is not installed, I am testing no load kV output of motor at 9t and also using 2 phase lines and EagleTree v3 logger I am able to measure no load of the internal inrunner.

I will be testing on 10S (37v) and 12S (44.4) using the stock controller and setup then moving on to check 14S (51.8), 15S (55.5) which I've tested with success on the stock controller of the Gen1 system and then moving up to 16S, 18S, 20S and finally 24S all using a modified EB806 and EB206 (old and new infineons) before installing on a 20" 2012 Downtube Nova folding bike.

Results will be posted by tommorow and install will commence tonight (unless my new HobGoblin or Trek Fuel EX8 Full Suspension bikes and my new Recumpence Dual Davinci drive arrive and distract me with a new build)

Upon first inspection, or rather item glaring at me is the use of a chain tensioner... based on the design of the motor mount and flanging I am dissappointed that one is even required, should be a sliding adjustment or a link and half link?

One other issue is with the freewheeling crankset - unlike Gen1 GNG the Gen2 has 38t for both motor drive and pedal input. That means final ratio from motor output 9T to the Crankset 38T is a reduction of just 4.22:1 but the bigger issue is the normal chainring (for pedal input on the 7 speed Nova) is 46 Tooth which is a drastic reduction in potential input cadence (in the wrong direction) taking what was an up gearing of 5.11:1 to 4.22:1 which means a comfortable cadence of about 90 (comfortable cadence to me) which used to produce a top speed (flats) with a 160 lb rider to a maximum of 460 RPM or 27 mph down to 380 RPM or 22.5 MPH.

I will attempt to locate a replacement 4 bolt crank for pedal input with 46T to keep proper pedal cadence and speeds.
Click to expand...
Sounds like you are going to put the GNG2 through it's paces. Makes sense that the best modification to be made is at the motor freewheeling gear, which is considered too low toothcount for chain durability. Solving it would be to increase the tooth count. Also, increasing the pedal crank tooth count should help with cadence issues as well. I'm looking forward to seeing you achieve harmonic bliss with this motor as I'll probably be copying you. I have the same motor and like you haven't installed it yet. I'm waiting to build my battery system first to go with this GNG motor/controller and another bike build revolving around a geared hub. Be careful of the overvolting past 60V though, I'd hate to see you burn this little motor when loaded down.
 
Can anyone tell how much drag this motor gives when pedaled without power? I need a nicely freewheeling and maintennance free motor for my velomobile (through the gears -> that means a mid-drive).
IF the 9 tooth sprocket on the motor wears out chain and sprocket too quickly, can it be replaced? Can anyone post photos and specs about this little sprocket? Where can one buy replacement parts?
IF the 9 tooth sprocket is too rough for bicycle chain, maybe using non-bicycle chain of shorter links is the answer? There are cheap and durable alternatives for bicycle chain, that's what some people are using with GNG V1 as primary chain. Then sprockets also need to be replaced.
 
well my gen2 is holding up jus fine so far but then it has been sitting in the shed most of the time. If the chain wears(and it has stretched) I'll just buy a new one.
 
No news yet - some preliminary bench no load testing to confirm / disprove factory claims (on just this motor, not sure of others).

Soon as I have it I will post -

For those asking though about freewheeling - it has been reported that it's an issue, or has a little bit of resistance to begin but with use it will wear in and work fine (not my experience but I have none yet).

-Mike
 
I am Planning on getting one of these in the coming weeks, I will def be following this thread, looking forward to hearing more about this Drive.
Great Forum! I have learn so much in only a few days! Cant wait to build my first E Bike!
 
AlSpong said:
More shenanigans ... Not sure if this related to my previous post but the freewheel bearings blew out ..... Anyways thought I'd try to get a local replacement and have found the thread on the replacement freewheel is different to the gng. Has anybody found this , do freewheels generally come with different internal threads ... Love to get my bike going ASAP and not have to wait for 3weeks for parts to arrive...... I'm considering having the crank thread recut to fit the new freewheel .. It's a cheapy .. Dicko or something like that
Click to expand...

Im gradually finding parts for my gng gen2 .... Ive just ordered new crank arms from eclipsecycles in the uk after following a lead to cyclone tiawan and discovering hideously expensive postage to australia . From uk much cheaper !
I havent pin pointed the problem yet , but im hoping it was a bodgey thread in the crank arm ... If not then i will replace the bb ...... Have not had much help through gng .. Doesnt have parts etc , feel like he doesnt know his product .... At one point he told me that the freewheel couldnt be overtightened on the crank arm .... I suggested that this was complete bull given the self tightening pressure created by foot pedalling and didnt get a response back ..... Other than he would sell me a new arm when he had them ... Not too impressed.... I guess you get what yobpay for ...... By the way my controller always sparks when i join it to the battery ... Is that normal ?
 
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