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

[guyavitov]

Now I discovered that the main crank shaft is bent, does the 150mm sickbikeparts one will hold well on a DH bike (jumps and such?)

I'm sure there are stronger BB shafts than the "lowest bidder" suppliers for GNG, but several builders have posted that a full-suspension bike makes life much easier on the BB-shaft compared to a hardtail DH frame on jumps. by the way, if you have a hardtail, I highly recommend the $120 Thudbustes seatpost.

I have specialized bighit with fox vanilla on the back, so its pretty full suspension.

only a half meter jump caused this.

 

[Cyclebutt]

Hi Guys,
So I finally managed to get the belt ruined after about 35km (on 20S Lipo, 12fets Lyen controller limited to 45A)

I replaced it with #25 chain, 11t-65t sprocket.
And also replaced the horrible crank freewheel (with the sickbikeparts HD one)

Now I discovered that the main crank shaft is bent, does the 150mm sickbikeparts one will hold well on a DH bike (jumps and such?)
Thanks.

You might want to PM BZHWindtalker, I'm pretty sure the Sickbikeparts one is longer on the wrong side ( or there was some other issue with it).

The sealed units (152mm) are long on the wrong side. Bare spindle is 158mm, see photo of the ones I have.

 

[justlooking]

can the outer barrel be cut then the ends reversed??
cut where the line is in the picture ??
is that a possability ?

 

[Denisesewa]

can the outer barrel be cut then the ends reversed??
cut where the line is in the picture ??
is that a possability ?


I would think it would be possible to dissasemble the unit and reverse the shaft, I once tried to dissasemble one with no success but that was many years ago, might have to dig out an old BB and give it another try.

 

[bzhwindtalker]

I completly took the GNG BB apart and it was pretty easy but those SBP units may be harder, never tryed.

 

[LightningRods]

Could be a nice combo with this 18 tooth 15mm HTD:
http://www.ebay.com/itm/HTD-5mm-Pit...omation_Control_ET&hash=item3375624e81&_uhb=1
But i really like the #25 chain. Feels like the definite solution. Strong, reliable and quiet. This belt mod would still need the motorpulley file off.
Having the freewheel on the primary have been discussed a couple of pages back. There will be more force needed when pedaling because of rotating the jackshaft with its bearings and rubberseals, this resistance is multiplied by the secondary reduction(when pedaling).
btw One of the real benefits with this kit is that it let you pedal it with quite low resistance.

Christer- I think your reasoning is correct. The drive pulley has too small of a tooth count for good engagement. 14T is listed as "sub optimal" for 5mm pitch and "may cause skipping and accelerated belt wear". 16T is supposed to be adequate. 18T would be very positive but we'd lose a lot of reduction. Every tooth off of the driver is worth between 5 and 7 on the driven depending on it's size.

I've been following the discussion on moving the freewheel and I understand the reservations about pedaling drag. So far we've just been discussing it in theory. The sprocket is so inexpensive I'm tempted to try it and see how it actually feels. If it's acceptable it's a tempting mod because many freewheels up to the heavy duty White Bros freewheel can fit. It it turns out not to be good to have the freewheel on the primary side but I like the 120T sprocket, "a couple of zaps with the MIG welder and no more freewheel".

I'm just being stubborn about the belt drive. Since several people have solved for converting to chain primary I wouldn't be contributing anything by going the same route. If I can make the belt work (which is what I really want anyway) then people will have a choice which way to go. I think that for e-bikers who mostly ride on the street the belt is a better solution.

 

[skyungjae]

Could be a nice combo with this 18 tooth 15mm HTD:
http://www.ebay.com/itm/HTD-5mm-Pit...omation_Control_ET&hash=item3375624e81&_uhb=1
But i really like the #25 chain. Feels like the definite solution. Strong, reliable and quiet. This belt mod would still need the motorpulley file off.
Having the freewheel on the primary have been discussed a couple of pages back. There will be more force needed when pedaling because of rotating the jackshaft with its bearings and rubberseals, this resistance is multiplied by the secondary reduction(when pedaling).
btw One of the real benefits with this kit is that it let you pedal it with quite low resistance.

Christer- I think your reasoning is correct. The drive pulley has too small of a tooth count for good engagement. 14T is listed as "sub optimal" for 5mm pitch and "may cause skipping and accelerated belt wear". 16T is supposed to be adequate. 18T would be very positive but we'd lose a lot of reduction. Every tooth off of the driver is worth between 5 and 7 on the driven depending on it's size.

I've been following the discussion on moving the freewheel and I understand the reservations about pedaling drag. So far we've just been discussing it in theory. The sprocket is so inexpensive I'm tempted to try it and see how it actually feels. If it's acceptable it's a tempting mod because many freewheels up to the heavy duty White Bros freewheel can fit. It it turns out not to be good to have the freewheel on the primary side but I like the 120T sprocket, "a couple of zaps with the MIG welder and no more freewheel".

I'm just being stubborn about the belt drive. Since several people have solved for converting to chain primary I wouldn't be contributing anything by going the same route. If I can make the belt work (which is what I really want anyway) then people will have a choice which way to go. I think that for e-bikers who mostly ride on the street the belt is a better solution.

I'd definitely prefer a long term belt solution. I wish I didn't have to replace nearly every component on the kit to make it work right. :lol:

 

[bee]

Just took apart my BB and it turns out I have what I think is an "American BMX BB", after popping everything out, I have a non-threaded hole that is 41.275mm x 68mm.

The GNG is a threaded Euro BB, right? Do I just need an adapter like this to install the GNG BB?

http://www.ebay.ca/itm/BB-Conversion-Bp-American-To-Euro-NEW-TP501-/130731369930?pt=Cycling_Parts_Accessories&hash=item1e703265ca&_uhb=1#ht_1111wt_1139

Now before I start installing the cheap GNG BB, I'm wondering if I can do anything with the existing 145mm ISIS crankshaft that came on the bike. It came with a ton of washers on each side so I could definitely move the crank a few mm to the right to make room for the GNG chainring assembly.

Are people fabbing up larger adapters/plates for the chainring to use an ISIS crank, or would I just need to find a 'thinner' (same OD but larger ID) bearing to use my nice fat 19mm ISIS crank?

Thanks again for the advice everyone!

 

[spinningmagnets]

If you have a hardtail bike and run fast on a downhill with lots of bumps, the stock GNG BB-shaft will not survive long. If you are riding on a street commute across a fairly smooth path, the stock parts should last a long enough time for you to sort out what upgrades you want to get eventually with no rush.

There are some smart people working on sourcing parts to make a list for a very strong generic BB-drive, but there is no definitive answer for that yet.

"strong freewheeling crankset"
http://endless-sphere.com/forums/viewtopic.php?f=28&t=47618

 

[bee]

Looks like everyone is sticking to euro/mountain threaded cranks since that is how the GNG kit is secured to the frame. Don't think I can do much with the american/spanish/mid BB setup I have.

The adapter I linked to above adds a lip to the BB so it looks like it might be better to press fit a euro BB shell like this http://www.paragonmachineworks.com/cgi-bin/commerce.cgi?preadd=action&key=BB0023

edit:
I might just grab another bike for this project, I think I'll have more fun with a geared bike and front suspension, and now is a great time to find cheap bikes.

 

[LightningRods]

So after a week of corresponding with a helpful gentleman named Daniel at BrecoFlex and exchanging numerous drawings and measurements, we came up with this:

It's a beautifully CNC crafted, 100 tooth, 20 mm wide, 5mm AT5 pitch aluminum pulley that will bolt right onto the GNG jackshaft. It's perfect.

It also costs this:

If 30 of us duct taped our wallets together we could each get one of these beauties for a mere $171 apiece. Ouch.

If you look further down the price list you'll see that I also spec'd a 14 tooth 20mm drive sprocket. Those are more possible. If 30 of us went in together we could get those for $25.75 each. I think that would be worth it. Unfortunately this one is an AT5 which means it won't work with any cheapie HTD pulleys or belts.

Ordering a CNCed HTD sprocket from BrecoFlex is also a possibility if Daniel is still speaking to me.

I also have a quote request in at a company that makes decent looking fiberglass reinforced nylon pulleys with aluminum hubs. I'll report back on how that turns out.

My engineering drawings are in at the metal fabrication shop to get the 68mm adjustable BB sheets made. I should get a firm bid on that tomorrow. If you are one of those 73mm guys looking for a GNG solution give me a PM and I'll look into getting a run of 73mm BB sets made.

 

[bee]

Some of the 3d printer folks are using nylon in their printers now. Maybe a 3d printed pulley would work? There is is a parametric generation script here that does AT5: http://www.thingiverse.com/thing:16627

I can print one up in ABS for you if you want to design something with a more rigid or metal attachment to the shaft.

You guys should post up your 3d models/designs of the GNG kit or mods to save other people from having to draw them again. I'm planning to design some brackets for my batteries and a dirt guard for the belt once I get everything together.

 

[heathyoung]

Faaaaaaarrrrr. Out. Thats pricey.

Makes those chain conversions seem much more palatable now

Where next is the question? The 3D printing stuff looks interesting - http://forums.reprap.org/read.php?2,117184

And a printed HTD pulley - http://www.heliumfrog.net63.net/hf06robot/toothedgear.jpg

Hmmm....

 

[skyungjae]

Faaaaaaarrrrr. Out. Thats pricey.

Makes those chain conversions seem much more palatable now

Where next is the question? The 3D printing stuff looks interesting - http://forums.reprap.org/read.php?2,117184

And a printed HTD pulley - http://www.heliumfrog.net63.net/hf06robot/toothedgear.jpg

Hmmm....

I'm thinking just having a handful of 475-5M-15 belts in my battery bag may be more economical. :lol:

 

[deepfraught]

Great work LightningRods!
I was half asleep last night but thought my A-Line had greater than 68mm, and 73mm sounds right, so will PM about a set of both BB sheets.

I noticed the current drive sprocket felt like as sharp as the crank of the pedals... will smoothing the edges a touch help belt life, or is it simply too small?

I also want to keep the belt for the different look, belts here mean Mad Max mean supercharged

For my 100mm BB shell fat sand bike, I found a front hub with 100mm dropouts would suit a DIY BB sheet job following the GNG hub kit... but opening the hub seeing all the extra components, bearings, clutch, I appreciate direct drive a lot more.

 

[LightningRods]

I'm also looking into having one set of pulleys CNCed and then pulling a mold off of them. I can try 2 part industrial resin (like hard hat material) and see how that holds up. It pours into the mold like water and has a perfect finish. People make small boat propellors with the stuff.

 

[Rollodo]

Not that I'd buy a $3K bike for the sole purpose of mounting a GNG kit on it, can it be mounted on a GT Fury?

http://www.bikemag.com/files/2011/01/wpid-MG_6531.jpg

http://3.bp.blogspot.com/_DNsN7wVTY...AZU/Cr-kt8HKWOs/s640/gt_fury_swingarm_600.jpg

 

[gestalt]

I'm also looking into having one set of pulleys CNCed and then pulling a mold off of them. I can try 2 part industrial resin (like hard hat material) and see how that holds up. It pours into the mold like water and has a perfect finish. People make small boat propellors with the stuff.

How about having the part 3d printed and making a mold from that? Might be slightly less expensive.

 

[Miles]

You can get a 95t pulley here: http://tncscooters.com/index.php?route=product/product&path=63_94&product_id=463

 

[Miles]

16t to 95t is close to the original ratio. Any specialist supplier will split off a belt to 20mm width or whatever the maximum is that will fit. A 20mm HTD belt on 16t to 95t pulleys, without an idler, should be good for about 8 Nm nominal torque, at the drive pulley.

 

[crossbreak]

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

 

[christerljung]

Interresting. What are facts inputed to get the graph?
It is important to know how wide rpm-range the motor can handle. But even if it runs less efficient at higher volts, the power could still be very usefull.

 

[deepfraught]

I compared the Truvativ Howitzer XR BB of 2009 Norco A-Line, to the stock GNG.
It looks like the GNG plates will take place of one washer on each side, with the drive side having 2 washers one can remain.
edit: confirmed fitted back with motor mounted nicely with one washer removed from each side of Howitzer BB.
edit2: oops the GNG freewheel in chainring won't go over the external BB bearings. Stock BB it is, if I can find a tool to thread the BB in.

 

[crossbreak]

Interresting. What are facts inputed to get the graph?
It is important to know how wide rpm-range the motor can handle. But even if it runs less efficient at higher volts, the power could still be very usefull.

Just click the link or look in the wiki (http://endless-sphere.com/w/index.php/EBike_Motors_Middrive_GNG_Gen1). The Data input came from you mostly

i dont get what you mean with rpm range? If you mean the torque curve, then I can only repeat over-and-over that one should set phase current limit close to battery current, to get the most power through the belt without cavity (http://endless-sphere.com/w/index.php/EBike_Controllers).

If you mean the rpm itself, then just look at the yellow curve fall. Here I made a graph with some comments: http://endless-sphere.com/forums/viewtopic.php?f=28&t=45245&start=435#p700523


Plz remind that these calcs never take care of eddy current loss, so read the higher voltage graphs with care, (i.e. 24s lipo stories makes absolutely no sense)

 

[speedmd]

Would like to see the data/chart on the GEN 2.

Another Pulley source for bigger 5mm belt units. Split type. http://www.cometkartsales.com/store/belts/5sprockets.htm