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

[ebiker1]

i'm in the middle of putting one of these on Hummer(montague paratrooper) but have lost the installation manual. i emailed gng today for a copy, so we'll see how long that takes. but anyway, the motor fits on Really nice! the bike will still fold nicely and i've got an old set of tora solo air to put on it. i read the posts (or is that thread) and am encouraged that this is gonna be good. i weigh 215 and live on a pretty big hill above town. i've already found out that a bmc v2 with a 48v 10a/h lifepo won't even get me up the easy way, with pedaling! so i decided the solution is a mid-drive. for roughly $450 this seems like a good way to start. at some point i will probably want a better controller, but am looking forward to just getting it running with what i have. will post pic's after it's done.

 

[d8veh]

I run mine with a 36v controller. I'm using a cheapo 9FET 22amp one from BMSBattery, but I soldered the shunt to get 25 amps. It'll do about 25mph on the flat and is too fierce in the bottom gears, but will pull away OK in top gear if you're lazy. It's difficult to compare efficiency because, unlike a hub motor, full power is available all the time and at whatever speed. It's quite good fun when you're already going down a steep hill at 30mph, to open the throttle and still get an additional 1000w accelerating you up to 40mph, which wouldn't happen with a hub-motor. If you're sensible with the throttle (which isn't easy) it uses about the same power as my 500w rear Bafang BPM motor.

Cadence is about right, I'd say. No-loadis about 125, but it's less under load

You can buy the kit with a 36v 22amp controller as an option.

I also tried it at 15amps , but then it could only climb steep hills slowly in first gear and it felt relatively gutless.

 

[neptronix]

Thanks d8veh;
What is your cruising watts at 20-25mph? just curious, because i know these systems can be lossy. I'm just wondering how lossy they are.

 

[parajared]

According to Sheldon Brown's gear calculator: http://www.sheldonbrown.com/gears/
If you use a 52 tooth chainwheel on the front and a 11t cassette on the rear you could hit 44mph at 120 rpm!
Is this reasonable for the gng, or do you start slipping gears and breaking stuff before you hit that kind of speed.

Is 32 teeth front, 30 teeth rear (10mph at 120rpm) enough to climb stuff so steep your tire slips out rather than the bike running out of power, or do you have to go lower to reach that kind of performance?

 

[neptronix]

44mph requires about 2500w of power. You could gear your bike for that kinda power, but i think you'd burn out the motor by then!

 

[Rassy]

Jenny wrote:

Also, what is it like, pedalling power-off? Is there a second freewheel in the crank or one in the layshaft?

Yes, there is a freewheel on the jackshaft between the motor and the crank as well as the one on the crank. So when you wish to pedal without running the motor your only penalty is rotating the short chain to the jackshaft, and of course the sprocket wheel on the jackshaft.

There have been several discussion items concerning the cadence of this kit. Remember that the 150 RPM is a noload speed. Even though under most conditions it can spin the cranks faster than I like, it is easy to control with the throttle and use a gear and speed that allows comfortable pedaling. With the stock 48 volt system and gears there is always a selection available up to 20 MPH. The bike I put it on does have 700C wheels so your results would be different for a smaller diameter wheel.

 

[parajared]

I counted the teeth in this picture and there appears to be 44 teeth on the top gear. Sheldon Brown's calculator puts top speed at 37mph on a 26" rim (11t rear). That wouldn't be too bad if that could be done without breaking the kit.

The M55 hybrid claims it can go 40mph pulling 1200 watts, christerljung runs his GNG at 3500watts, could this be a poor man's almost M55? ($40,500 cheaper)

 

[neptronix]

The M55 hybrid claims it can go 40mph pulling 1200 watts, christerljung runs his GNG at 1200watts, could this be a poor man's almost M55? ($40,500 cheaper)

Heh, downhill, definitely not on the flats. Check the ebikes.ca simulator. It really does take about >2000 watts at 40mph.

>1000w seems to be where bike chain and derailleurs start having serious problems. That's when you start needing BMX/single speed chain and such.

 

[wavezz2k]

christerljung » 70+ volts and 30 amp , seems that is a lot more than 1000 watt, that's been shown w/CA on his drive, chain seems to be OK so far, most agree the weak link to be belt and idler.

- Anyone seen or heard of experiences with running 1000watt mid drive into a Alfine 8spd internal hub? chain aligns like a one speed fixie, but still shifts. I've found they are very solid in normal use, hard riding has always worked perfect, but haven't seen one on a e-drive setup. I prefer near instant shifts that are ultra smooth also.

I'll posts pics of my build shortly: full suspension MTB, stock GNG & controller (stock 1st, mods 2nd), w/ 8spd internal hub, upsized hydraulic discs. Plan is to increment up the voltage pack until belt starts to skip - likely 1st upgrade will be mods nc pulley plate with tensioner on both sides to improve the single idler (not so happy stock). Personally, Tweaks to this kit is definitely the path (IMHO), rather than a scratch build mid-drive.

BTW #2. Did someone track down this motor specs, specifically if there were some CAD drawings of the dimensions and bolt patterns? not so fun diddling with calipers to work out key numbers.

 

[crossbreak]

- Anyone seen or heard of experiences with running 1000watt mid drive into a Alfine 8spd internal hub? chain aligns like a one speed fixie, but still shifts. I've found they are very solid in normal use, hard riding has always worked perfect, but haven't seen one on a e-drive setup. I prefer near instant shifts that are ultra smooth also.

These alfine use roller type clutches which tend to wear out rapidly if used with high power. When used with the stock controller it should hold up quite a while. IMO using a 13-32T makes more sense, since they are cheap and can be swapped each 2000miles, when used with a thousand watts. Swapping an alfine each 2000miles seems to be a bit expensive. My cheap 11T and 12T cassette sprockets wore out within a few hundred kilometers with only 700Watts through the controller, that's why I use the $15 shimano 13-32T cassettes now, which hold up much better. The more expensive 11-32T cassettes are no option for me also, wore out one, it held up only slightly longer.

The M55, like most other high power e-bikes, uses the rohloff hub, which seems to hold up well even above 1000W. Sadly this is the only hub on the market which does so.

 

[d8veh]

Thanks d8veh;
What is your cruising watts at 20-25mph? just curious, because i know these systems can be lossy. I'm just wondering how lossy they are.

I haven't got a wattmeter on this bike, but I can tell you it's about 900w from the battery. I had a battery with 20 amp BMS, which tripped if you held the throttle wide open for more than 5 secs. With these crank-drives, you can always change up a gear to drop the motor back into it's high torque/high current zone, so economy of battery is never going to be a strong point unless you want to slow down a bit and use the minimum power necessary. I find myself going a lot faster than I do with hub-motors, and I use WOT a lot more. I think I need a cruise control to slow down.

 

[gestalt]

I've really been paying a lot of attention to all these GNG threads. bzhwindtalker, F-T, christerljung and tri-lobe, you guys rule for documenting this drive so well with pics and vid. then the rest of the ES research team, old jon chan over at GNG has no idea what an awesome international media firm he has working pro bono for him :lol: I saw in his forum though that he is crazy busy.

but to the meat of the matter. I have a good buddy of mine that is going to pull the trigger on a kit along with myself and shot me an email about a prospective bike and was wondering if it would be a good fit. http://providence.craigslist.org/bik/3296928518.html

seems like a good candidate, BB is in the right place, price about right with some good components. but as he'll most likely be building his battery pack out of my konion stash the question is will 48v and 15ah fit in that triangle if we were building the cells perpendicular to the frame tubes? that would be around 160 cells. can't really measure it from the ad save a basic shoot from the hip with relationship to the water bottle size.

my gut is saying no, but thought someone with more experience could chime in.

 

[christerljung]

That felt-frame looks great! A lipo setup would fit nice in the triangle. Cant say for Lifepo4, no experience from them.

Here is a pic of the first reduction. The bigger wheel got a pin key. The small pulley seem to be part of the motorshaft, as timbuck already stated.

Im going for a 13/72 chain-drive. #25 chain. From this place probably:
http://www.electricscooterparts.com/sprockets25chain.html

 

[snellemin]

That pulley on the motor is in front of the bearing. Must be just press fitted.

Something like this might take it off.

 

[full-throttle]

That pulley on the motor is in front of the bearing. Must be just press fitted.

Could also be threaded.. Who knows

 

[snellemin]

hmmmm, threaded huh. Got to mess with mine then and see what is up.

 

[wavezz2k]

Im going for a 13/72 chain-drive. #25 chain. From this place probably:
http://www.electricscooterparts.com/sprockets25chain.html

I've ordered several small components (wiring connectors, brushed controller) from those guys, and stateside they ship instantly. Usually I get packages in 2 days - they're west coast N. California - so, it would be international ship to Sweden.

The small pulley doesn't seem to have a simple solution (yet) - someone's gonna figure this out soon, is my predict.

 

[m.agar]

I would like to hear from and see pictures of kits assembled and working. The 36v kit looks very good for the price and for what i want to achieve.

 

[Haste]

this looks great, but honestly if your wanting a daily..go hub!

i do a 22 mile roundtrip 4x a week...and cant imagine putting almost 100 miles a week on something like this... quite the kit for price however.

 

[heathyoung]

Its not a bad design, I've just ordered one myself to have a play with...

Hubs - depends on how you treat your daily commuter, I destroy rims on a regular basis And they are too heavy for the way I ride as well, so many pinch flats on the rear hopping up on gutters etc, broken spokes - arg. Over it. Hub also has a temptation to go waay too fast for a bicycle as well, something I know well.

Something light and nimble appeals at the moment, I miss the go-anywhere of the dirtbike, but not the noise!

 

[Cyclebutt]

Its not a bad design, I've just ordered one myself to have a play with...

Hubs - depends on how you treat your daily commuter, I destroy rims on a regular basis And they are too heavy for the way I ride as well, so many pinch flats on the rear hopping up on gutters etc, broken spokes - arg. Over it. Hub also has a temptation to go waay too fast for a bicycle as well, something I know well.

Something light and nimble appeals at the moment, I miss the go-anywhere of the dirtbike, but not the noise!

I bent a rim (pothole) on my rear direct drive hub, once. Kenda K838 was not fazed but the ride home was bumpy. Re-laced wheel with better cross pattern, much stronger now.

With this bike, battery in a backpack, no heavy HUBS, and FAT off-road tires, I'm expecting better results. Rain has stopped my further testing today, kit requires some mods but I would buy it again.

 

[parajared]

My kit came in today. Only took 5 days to arrive.
Here's a video of some of the quirks I encountered installing the thing. I have run out of sunlight here so no riding yet, but I hope to finish it tomorrow so I can have some actual performance videos for you guys.

[youtube]yyX61_-HlVw[/youtube]

 

[Cyclebutt]

My kit came in today. Only took 5 days to arrive.
Here's a video of some of the quirks I encountered installing the thing. I have run out of sunlight here so no riding yet, but I hope to finish it tomorrow so I can have some actual performance videos for you guys.

Had issues with that chain idler as well. Swapped for a big automotive spring from the collection. Just finished my chain guide (photos coming) and new cassette, shifter and derailleur arrived yesterday, work to do. Are you going to run BOTH drive systems together? THAT would be fun to try and see.

 

[parajared]

Are you going to run BOTH drive systems together? THAT would be fun to try and see.

I might try running both just to see what happens, but I presume I will end up running one or the other in the long run.

I haven't put my regular tires on yet; I was too eager to give it a try and just went for it with my hub still on (not powered). I encountered a few problems:
-when the motor gets to around the 75% of top speed mark the motor does a weird skipping thing. Belt and chain aren't skipping it's the motor or controller doing something. (see video)
-when run at 1000 watts it lingers at the 75% zone and makes for a rough ride, but when upped to 1500 watts it pushes right past the rough part.
-when run on the 11 tooth gear it skips teeth at 1500 watts. When run on the 13 tooth gear I had no problems. No skips from the belt, or the other chain.
-slow top speed on 1000 watts, but decent top speed at 1500 watts. I need to hook up my speedometer to know the exact speed, but I suspect low 30s.
-The motor at wot is too fast for your legs to keep up and help with the peddling. (12s lipo 1500 watts)

It's not bad noise wise. It's quieter than my 9c when it makes the "9c hum", but louder than when the 9c is in regular operation. It is about the noise level of a regular sewing machine.

When first driven the cog that drives the belt made a mild grinding sound, and a few metal flakes came off. After about 300 meters or so it ground whatever was giving it a problem off and started running quietly again.

[youtube]-vDdGKxFPIQ[/youtube]

 

[k-harvey]

just priced the difference for in New Zealand & they were on the par I'd like to see the power difference between 1200w cyclone & this as my cyclone on the 36v 960w have had to increase crankdrive cog size as should rev higher on hills always have a 48 cog for peddling & the 11 at the hub till i fitted the nuvinci which is slower .i never go slowerthan 20k up hills & hit 40 before i fitted nuvinci.