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

[skyungjae]

I saw chalo on a recent outing.

..

No need to insult the guy. He's got a point and he's supporting it with other people's experiences. I think we've just all stepped off on the wrong foot here. "Logic" is subjective as are our various reasons for having e-bikes regardless of hub or mid drive.

As the greatest U.S. Present Abraham Lincoln stated in 1766, "Can't we all just get along?"

 

[bee]

Here's a better angle

That looks better. We are getting some appreciation for how GNG got painted into a corner in terms of using a too small drive pulley. Every tooth added to the drive pulley requires around 6 on the driven. That's still a damn fine looking bike!

With how close the gears are to each other, I'm tempted by a herringbone gear setup

That's a really good point, Bee. I don't know how much of an appetite you have for messing with this, but there are lots of options beyond HTD5. HTD8 or 8mm pitch HTD has much better torque handling capability. Above that is the GT2 which completely outperforms the HTD belt and link chain as well. I felt constrained to HTD5 because I was just trying to solve for the drive pulley and tie into existing inexpensive driven pulleys. Since you are making everything from scratch now you really should step up to a more performance oriented belt/pulley profile.

Gears are an interesting idea. The uncompromising hard mesh of their teeth would push your process to it's limits. They'd probably be noisy little suckers, even made out of ABS or resin. It would be nice to have a sound deadening enclosure. But still, a compact, multi stage reduction that doesn't cost a fortune.... if you could do it, it would shake things up for sure.

I was mostly kidding with the gears, the gear enclosed reduction on my 2-stroke bicycle is ridiculously loud even with sound dampeners, I can only imagine how those herringbone gears sound like in the open at speed

Swapping in another tooth profile takes a few minutes with the parametric pulleys, the script has all the standard ones already built in. I'm going to give the larger HTD5 belts I ordered a try, and if I need more gear reduction than that I'm going to have to grind down the motor shaft because as you said, we're stuck in a corner with the stock one, it's too small by itself and too big for an 18t cog.

 

[LightningRods]

As the greatest U.S. Present Abraham Lincoln stated in 1766, "Can't we all just get along?"

Wasn't that Reginald Denny after nearly getting beaten to death in the early '90s LA riots? :?

 

[LightningRods]

I was mostly kidding with the gears, the gear enclosed reduction on my 2-stroke bicycle is ridiculously loud even with sound dampeners, I can only imagine how those herringbone gears sound like in the open at speed

Swapping in another tooth profile takes a few minutes with the parametric pulleys, the script has all the standard ones already built in. I'm going to give the larger HTD5 belts I ordered a try, and if I need more gear reduction than that I'm going to have to grind down the motor shaft because as you said, we're stuck in a corner with the stock one, it's too small by itself and too big for an 18t cog.

Everywhere you turn there is a compromise. I'm starting to envy the people who just said to hell with it and put primary chains on. The weather is getting better here. I won't be happy playing indoors much longer.

 

[skyungjae]

I was mostly kidding with the gears, the gear enclosed reduction on my 2-stroke bicycle is ridiculously loud even with sound dampeners, I can only imagine how those herringbone gears sound like in the open at speed

Swapping in another tooth profile takes a few minutes with the parametric pulleys, the script has all the standard ones already built in. I'm going to give the larger HTD5 belts I ordered a try, and if I need more gear reduction than that I'm going to have to grind down the motor shaft because as you said, we're stuck in a corner with the stock one, it's too small by itself and too big for an 18t cog.

Everywhere you turn there is a compromise. I'm starting to envy the people who just said to hell with it and put primary chains on. The weather is getting better here. I won't be happy playing indoors much longer.

Ouch, Western Oregon... I spent about 9 months in Sheridan back in '95. It rained like half the time I was there. First time I've ever seen snow fall, so I guess that was cool. :wink:

 

[LightningRods]

Ouch, Western Oregon... I spent about 9 months in Sheridan back in '95. It rained like half the time I was there. First time I've ever seen snow fall, so I guess that was cool. :wink:

Yep. About 7 months of the year you don't need spandex here in Oregon, you need a wet suit. :wink:

 

[flyinmonkie]

Let's move all the debate to this thread

http://endless-sphere.com/forums/viewtopic.php?f=26&t=48289

While we are at it, Miles can you start a thread for what animal makes the best drive? That was too funny.

All right back on topic.

Clay

 

[maramusa]

Anyone use this system as a commuter? I have a 700c hybrid I want for long distance and hills, road path only.
Or is it only suited to mountain bikes? and I would be better going for hub motor?

 

[bee]

I was mostly kidding with the gears, the gear enclosed reduction on my 2-stroke bicycle is ridiculously loud even with sound dampeners, I can only imagine how those herringbone gears sound like in the open at speed

Swapping in another tooth profile takes a few minutes with the parametric pulleys, the script has all the standard ones already built in. I'm going to give the larger HTD5 belts I ordered a try, and if I need more gear reduction than that I'm going to have to grind down the motor shaft because as you said, we're stuck in a corner with the stock one, it's too small by itself and too big for an 18t cog.

Everywhere you turn there is a compromise. I'm starting to envy the people who just said to hell with it and put primary chains on. The weather is getting better here. I won't be happy playing indoors much longer.

I put the half-link and tensioner back on the secondary reduction to try out the 19t printed pulley while we have some unexpected nice weather here. No go! Way too much belt skipping with the 80t on there. I also got my 11,12,65 and 80 #25 sprockets today so I'll be installing those soon!

I test fitted the freewheel adapter which fits fine:

It also removed the wobble that was present in the primary side from the cast pulley which was making it very hard to eliminate belt skipping. I'm just not sure that these belts were meant to be used without some kind of tensioner or idler, the skipping problem is definitely due to a lack of belt tension, I think the tensioner will need to be added back for belt drive users, but it will need to be modded to function more to existing specs: http://www.gates.com/facts/documents/Gf000218.pdf

I'm also really tempted to try 80/11 ratio, something we can't do with belts!

 

[spinningmagnets]

would be better going for hub motor?

maramusa, the GNG has very specific benefits, and several drawbacks. Unless you are a garage experimenter with tools and skills, I would recommend avoiding this kit. My "go to" suggestion for anyone who wants a generic fairly trouble-free street commuter that is pretty easy to install, I recommend the cell_man 10T MAC on a rear wheel with a 48V battery. Top speed is roughly 25-MPH, and hill-climbing is very good.

Get the $15 upgrade, with fatter phase wires and a temp sensor. Get two torque arms.

http://em3ev.com/store/index.php?route=product/product&path=36&product_id=55

 

[Samd]

"Logic" is subjective as are our various reasons for having e-bikes regardless of hub or mid drive.

As the greatest U.S. Present Abraham Lincoln stated in 1766, "Can't we all just get along?"

Pig's bum - I have a Mech Eng degree. The formulas are finite, as is the science of efficiency at stake. Which product you want to choose is a subjective choice, but what we have been trolled into is an erroneous discussion of overall system efficiency.

You wouldn't go around telling medical doctors that logic is subjective.

 

[mr.electric]

A GNG with torque sensor and no throttle would be interesting to ride. You could probably still do a wheelie and smoke the rear tire if you were a skilled rider.
The front freewheel crank makes it hard to love the GNG for me. Maybe one of those torque sensing bbs, standard cranks and no throttle would be a nice match for the GNG. I understand most people want a throttle but I already own three or four ebikes with throttles.

 

[skyungjae]

"Logic" is subjective as are our various reasons for having e-bikes regardless of hub or mid drive.

As the greatest U.S. Present Abraham Lincoln stated in 1766, "Can't we all just get along?"

Pig's bum - I have a Mech Eng degree. The formulas are finite, as is the science of efficiency at stake. Which product you want to choose is a subjective choice, but what we have been trolled into is an erroneous discussion of overall system efficiency.

You wouldn't go around telling medical doctors that logic is subjective.

Funny you bring that up because it was a doctor that told me logic is subjective. :wink: My mom is currently has stage 4b cancer and is on her second round of chemo. She was a physician (pathologist to be specific), and my father is a pharmacist from USC. You'd think they would put all their trust in western medicine, but they actually have more faith in some Japanese herbal medicine called Fucoidan made from brown algae (sea weed). Of course this makes perfect sense to them which is why she is using it in parallel to the chemo. On the other hand, her doctor has advised against it since it' doesn't fall into the western way of thinking. Logic is reason given meaning by social reality. After all, what are formulas without people to validate them? Numbers and efficiency aside,logic is not always universal and what makes sense to you may not make sense to someone else.

I don't have a mechanical engineering degree, but I do have one in anthropology and, surprisingly, actually use it in my job. In civil litigation, regardless who brings up the allegations first, both parties feel like the victim and both parties feel like they are right regardless of facts and figures. Chalo does bring up some valid points, but his delivery is incredibly poor and not helpful (unless he thinks he's helping people by convincing them to give up on the GNG). In his mind he's right, and nothing we say or do will be able to change that. The whole reason why we're trying to improve on this system is because we are aware of the weaknesses and faults. In his mind, it's clearly more logical to go another route, so I can't blame him if he thinks we're wasting our time with these kits.

Anyhow, it appears Chalo has taken his 2 cents elsewhere. We can get back on topic and make the GNG into a better system. Also, any positive thoughts or prayers for my mother are also welcome.

 

[skyungjae]

A GNG with torque sensor and no throttle would be interesting to ride. You could probably still do a wheelie and smoke the rear tire if you were a skilled rider.
The front freewheel crank makes it hard to love the GNG for me. Maybe one of those torque sensing bbs, standard cranks and no throttle would be a nice match for the GNG. I understand most people want a throttle but I already own three or four ebikes with throttles.

That would actually be really cool.

 

[-dg]

Yep.
...
up to 98.6% see page 5 of full article (as I mentioned 200W)

Interesting paper. Looking at tables 1, 2, and 3 on page five you have cherry picked the highest number in the whole paper. Up to 98.6%, this is for 200 watts into a 52x21 sprocket set at 60 rpm, which for a 26" wheel is 11.5 mph. All the other test conditions are worse, most are in the high 80s and low 90s. What happens if one wishes to go faster than 11.5 mph? According to the Spicer paper:

These results for efficiency show that higher efficiencies are expected for those configurations that have larger sprockets in combination. This result agrees with the frictional loss models. Another trend, supported by the data in Table 2, indicates that the efficiency decreases with increasing rotation rate for constant power input.

Here is table 2:
Chain Drive Efficiencies for Different Drive Rotation Rates and Sprocket Configurations
„constant input power 100 W…

Gears   30 RPM  40 RPM   50 RPM   60 RPM   70 RPM   80 RPM  90 RPM
52–11    96.7    95.0     92.8     90.9     89.3     87.5    85.4
52–15    97.8    96.5     94.6     93.0     91.0     89.3    87.2
52–21     --     97.8     95.9     94.4     92.8     91.3    89.8

Sheldon Brown tells us "Most experienced cyclists pedal at cadences in the range of 70-90 RPM". 80 rpm with a 52x15 gear gives 21.5 mph a nice comfortable speed. Table 2 says that will be 89.3% efficient at 100 watts. Pedal faster or use a taller gear and it gets even worse. For typical cycling speeds and gearing Spicer's data sugggests efficiency is likely to be in the high 80s to low 90s percent. So this paper actually supports Chalo's claim of 90% more stongly than your claim of 99%.

...
So long sucker

Given how you use data, name calling is the stronger part of your argument.

 

[full-throttle]

Read what I wrote again. Look up the table for 200W.

Do you know what "up to" means?

Any more f#%$ing retards?

 

[-dg]

Do you know what "up to" means?

Sure. It's a polite phrase used to warn the reader that they are being mislead even though not technically lied to.

 

[Miles]

See also:
http://endless-sphere.com/forums/viewtopic.php?p=185036#p185036
http://books.google.co.uk/books?id=0JJo6DlF9iMC&printsec=frontcover&dq=bicycling+science&hl=en&sa=X&ei=_cE5UdamGOmI0AX3i4HwAg&ved=0CDEQ6AEwAA#v=onepage&q=342&f=false [Page 342 to 345]

 

[Samd]

No chance skungjae.
Logic is universal and with the big three philosophers long dead there is no chance to modify it to suit your own ends skungjae.

Whilst I remain a consistent and active cancer donor and am sorry for your mum, you howevermanaged to rack up an impressive list of logical fallacies back there:
An appeal to emotion,
An anecdotal ,
An appeal from authority,
A strawman, tu quoque and ad hominem all in one shot to Chalo.
Logic isn't some mystical bullshit wrapped in ether. These guys are being methodical when it comes to the topic at hand however.

Here's a cheatsheet.
https://yourlogicalfallacyis.com/poster

 

[LightningRods]

Skyungjae, you're a good man. Having grown up in Southern California I can say that tolerance is all that's going to keep humanity from destroying itself. Unfortunately, we also live in a time where black/white logic has become like a virus. People with some sort of agenda delight in saying the opposite of what is true and then belligerently, manipulatively, persistently sticking to their propaganda no matter how wrong they obviously are. Part of it is ego, refusing to be proven wrong, and part of it is just a blatant lack of respect for the truth.

Reduction systems are worth the losses in a well designed system. Transmissions are worth the losses in a well designed system. That is why mid drives, despite their complexity and packaging challenges, are worth the trouble. Torque multiplication is a powerful force. "Give me a long enough lever and a place to stand and I can move the world". Gearing is leverage.

The GNG kit is an interesting situation because it promises a complex, high dollar system at a developing world price. Is it a $3,000 EGO kit? Of course not. Does it deliver on all of it's promises? Sadly, no. But I'm not working with this kit because it's perfect and needs nothing. I'm working with it because it's a good basic framework to build a decent mid drive, still at a very good price. If I didn't enjoy these challenges I would choose a simpler and more obvious solution.

After several months of wrestling with the GNG I would say that the motor and the jackshaft are it's two worthwhile components as delivered. Several of us are looking into sourcing the motor separately (it looks to be available for about $35 in China) and then assembling a jackshaft from readily available parts. There are multiple threads chasing down the design and construction of a sturdy and reliable front freewheel crank set. I'm also interested in using the GNG motor to drive a rear mounted jackshaft and tying the pedal chain in there, avoiding running the motor through the crank set at all. A lot of it comes down to packaging. Lyen's controllers are obviously superior to what the GNG comes with and it's been proven that combined with a Magura throttle and a couple of resistors can create a control system that is both powerful and finely controllable.

I don't know how the reduction system will play out. All of Bee's hard work in printing pulleys of various sizes has shown the difficulties that caused the problems in the belt drive to begin with. If you start with the minimal 16 tooth pulley you end up with a large driven pulley and still not enough reduction. Another stage of reduction similar to Motomoto's beautiful mid drive build or Recumbence's two stage (three if you count the chain wheel) DaVinci drives would make the pulley sizes manageable. Or just switch to #219 chain. I am growing weary of the pulley/belt battle and I'm wanting to get out and use my bike.

Happy e-biking guys, whatever your ride of choice.

 

[skyungjae]

Skyungjae, you're a good man. Having grown up in Southern California I can say that tolerance is all that's going to keep humanity from destroying itself. Unfortunately, we also live in a time where black/white logic has become like a virus. People with some sort of agenda delight in saying the opposite of what is true and then belligerently, manipulatively, persistently sticking to their propaganda no matter how wrong they obviously are. Part of it is ego, refusing to be proven wrong, and part of it is just a blatant lack of respect for the truth.

Reduction systems are worth the losses in a well designed system. Transmissions are worth the losses in a well designed system. That is why mid drives, despite their complexity and packaging challenges, are worth the trouble. Torque multiplication is a powerful force. "Give me a long enough lever and a place to stand and I can move the world". Gearing is leverage.

The GNG kit is an interesting situation because it promises a complex, high dollar system at a developing world price. Is it a $3,000 EGO kit? Of course not. Does it deliver on all of it's promises? Sadly, no. But I'm not working with this kit because it's perfect and needs nothing. I'm working with it because it's a good basic framework to build a decent mid drive, still at a very good price. If I didn't enjoy these challenges I would choose a simpler and more obvious solution.

After several months of wrestling with the GNG I would say that the motor and the jackshaft are it's two worthwhile components as delivered. Several of us are looking into sourcing the motor separately (it looks to be available for about $35 in China) and then assembling a jackshaft from readily available parts. There are multiple threads chasing down the design and construction of a sturdy and reliable front freewheel crank set. I'm also interested in using the GNG motor to drive a rear mounted jackshaft and tying the pedal chain in there, avoiding running the motor through the crank set at all. A lot of it comes down to packaging. Lyen's controllers are obviously superior to what the GNG comes with and it's been proven that combined with a Magura throttle and a couple of resistors can create a control system that is both powerful and finely controllable.

I don't know how the reduction system will play out. All of Bee's hard work in printing pulleys of various sizes has shown the difficulties that caused the problems in the belt drive to begin with. If you start with the minimal 16 tooth pulley you end up with a large driven pulley and still not enough reduction. Another stage of reduction similar to Motomoto's beautiful mid drive build or Recumbence's two stage (three if you count the chain wheel) DaVinci drives would make the pulley sizes manageable. Or just switch to #219 chain. I am growing weary of the pulley/belt battle and I'm wanting to get out and use my bike.

Happy e-biking guys, whatever your ride of choice.

[youtube]i8R-AK1qAmA[/youtube]

This video led me to this video... by bzhwindtalker

[youtube]SDdmECbnugY[/youtube]

Which convinced me to purchase the kit expecting to do what the fellas were doing in the first video which led to the bent BB spindle. Hahahaha

I'd really love to see the EGO kit up close and personal. Though it doesn't offer any solutions regarding the belt drive and reduction issues, it could potentially give GNG users a BB that's can hold up to tree roots off road. From pictures, I've seen them use Echo freewheel ISIS cranks. What I'm trying to figure out is if the BB is proprietary to the system or if it's off the shelf. I wonder if ebikessf will freely give up that information. I guess it doesn't hurt to shoot them an email which I'll do after this post. The support bearing on the chain ring adapter won't fit around the spindle, but I'm sure it could be popped out or removed. It would put more stress on that 16T freewheel, but there are already other off the shelf replacements available for them. Anyhow, we know we can get ISIS freewheel cranks, but the search is still on for an ISIS bottom bracket with a long enough spindle.

I think we're doing a great job so far on the attempt of making the GNG more reliable and durable. Hopefully we can get somewhere regarding the reduction and harmonize the power with our pedaling.

Regarding sourcing the motor for about $35. Is that through Jon at GNG, or were y'all able to find an alternative supplier? I'm not sugguesting to undercut the guy, but with all the available modifications/upgrades, it would make a lot of sense just to buy those individual parts rather than ending up with a bunch of left over GNG parts. I know Jon is willing to sell some individual components for the kits. It would be great if we could piece together a couple ES build lists using this motor for this awesome community.

I must say, besides a few people that give unwarranted advice, specifically Chalo, ES is filled with very supportive members. It's very refreshing compared to other forums where starting a thread instantly gets flamed. :lol:

 

[DaveP]

I would like to echo the sentiments from bzwindtalker. A couple of years ago I built a front hub e bike which was not very good. My lack of knowledge, experience etc led me to put it in the garage and buy a Vectrix - which is fun. I don't want to go at high speed all the time, I just want to pedal around the hilly english countryside and enjoy myself. Why am I posting this? Because reading this thread enthused me to have another go.I don't know how successful I will be but I am confident that there are people on this thread that will answer the stupid questions I am sure to ask
Keep things positive and courteous - you will improve a product with a lot of potential and encourage a lot of people who are past their physical peak.

DaveP

 

[speedmd]

Back to GNG upgrades.

I got the modeling done on the eccentric jack shaft bearing cups. Looks like we can expect some 13- 14 mm of total adjustment (360 degrees) with a more realistic range of maybe half that with good meat left on the cups using 2" stock. Will post photos here and on shaft upgrade link as soon as done with the set up. Making a new aluminum hub for the 72 T sprocket as soon as I can find some stock. Lots of small changes still needed. Snow is soft and deep here today.

 

[gestalt]

the snow out there is nice today isn't it? seems to be better snow to ride in than the nemo snow, grippy and fluffy.

I have my pack essentially all wired up but uphill about two towns over. don't know if I'll be pedaling over there tonight. plus, I don't have my second set of lightningrods sheets or the 95 tooth pulley yet along with some other essentials.

 

[flyinmonkie]

skyungjae

I am betting that the ego uses standard isis bottom bracket and freewheel cranks. They may use a an eno flanged freewheel or an ACS, or just a cheap dicta one. But, they don't have a support bearing like the GNG freewheel crank. So it is like the cyclone freewheel crank just with better parts.

You could do the same on your GNG by just building your own freewheel crank with off the shelf parts and forgoing the support bearing. The eno has been shown to hole up fairly well, but isn't designed to be over run as it only has one row of bearings and is expensive. It is easily serviceable though. The ACS has 2 rows of bearings and is thought to be better suited to be over run, but I haven't seen many use it. It is much cheaper though.

Clay