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

Awesome ammunition, Miles! Thanks for that. I'll be sending this to Bobby when I give her the choice of a return authorization or my reversing the charge on my credit card. If they're smart they'll take the return auth because reversing the charges costs them an additional $25.
 
SDP18TGT2.jpg


The tooth profile does not look like the GT. Aside from less than a full radius at the bottom of the profile it looks closer to the HTD, at least to me.
 
speedmd said:
The tooth profile does not look like the GT. Aside from less than a full radius at the bottom of the profile it looks closer to the HTD, at least to me.
Click to expand...

I respectfully disagree, Doc.

SDP18TGT2-belts.jpg
 
spinningmagnets said:
Lets look at the "most bang for your buck" mods. Add LightningRods adjustable outer sheets to get rid of the horrible stock belt idler ($40?). Swap in a #25 chain on the primary (72T:12T) for a 6:1 reduction (another $40?).
.
Click to expand...
Is this the cost of the primary mod that Denisesewa made? Cogs and chain? Hmm, looks like this will be the way I go if/when I give up on the belt. Already have LightningRods sheets. Just need some time!
 
The $40 quoted is for parts only, the trick...is in filing the shaft stub down to 10mm with care so that it is fairly cylindrical. If you botch that job, and you'll need a new motor shaft.

12T, #25, 10mm bore, $6 plus tax and shipping
http://tncscooters.com/index.php?route=product/product&path=63_90&product_id=143

68T/72T/80T/90T...$18-$30...#25, bolt to the side of the stock GNG pulley
http://www.electricscooterparts.com/sprockets25chain.html

#25 half-link + master link
http://www.robotmarketplace.com/products/roller_chain.html

PM LightningRods for the adjustable primary sheet (adjustable motor sheets available too)
http://endless-sphere.com/forums/viewtopic.php?f=28&t=46891#p704262
http://endless-sphere.com/forums/memberlist.php?mode=viewprofile&u=30024

11mm bore FW adapter
http://endless-sphere.com/forums/viewtopic.php?f=28&t=46891#p695839

13T ACS-Crossfire FW, $21 (also, requires a $20 removal socket to get on and off)
http://www.amazon.com/ACS-13T-Crossfire-Metal--Metric/dp/B004HNRF86/

ebay: Cyclepro BMX freewheel remover
http://www.ebay.ca/itm/Cyclepro-BMX-Freewheel-Remover-/370614930418

Vuelta 48T-60T chainring, $30-$40
http://www.vueltausa.com/components/chainrings/se-chain-ring-130mm-38-60t-1.html

Be aware some frames do not allow a larger chainring, I now believe this is why the original kit has a 44T. It does not explain why they don't use an interface that allows a cheap and easy installation of a larger chainring (snellemin bought the bikemotive spider so he could use off-the-shelf chainrings). The red arrow points to where the chainring might not fit your frame if you don't measure first...

 
speedmd said:
The tooth profile is clearly not like the GT. The GT has tooth walls do not go parallel toward the tip as on the HT. The pulley teeth look clearly more like the HT to me. Has anyone put a belt against it to see if the tooth on the belt bottoms out as in the red-lined outline.
Click to expand...

I'm starting to think you're right, Doc. I did clamp a HTD on it and while the fit wasn't perfect, it wasn't far enough off to be a completely different belt type. It's a sloppy HTD with an odd flat bottom to the profile. It's all Thud's fault! He started this! :p

I just bought this pulley to check my own digital profile anyway. This pulley is only 19mm wide and I want a 23mm wide to run a 20 mm belt on. I'll make some subtle adjustments to the profile to make it fit the belt better and then have a prototype made.
 
I went with a 80:11 setup for a primary reduction of 7.3:1 and almost immediately destroyed a bunch of components on my bike while shifting under power. Gotta be extra careful when you're putting that much power through the bike!

I found all the parts on http://tncscooters.com/ except for the half-link which I found cheapest @ http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=251133890855 $1.50 + $11 for shipping to Canada (robotmarketplace wanted $22 shipping).

I was lazy and used a freewheel adapter which bolts right on to mount the sprocket instead of cutting up the stock pulley. TNC had the best shipping price to Canada and they use USPS which means no customs fees!

80t sprocket http://tncscooters.com/index.php?route=product/product&path=63_89&product_id=131
11t sprocket http://tncscooters.com/index.php?route=product/product&path=63_90&product_id=139
#25 chain with free master link http://tncscooters.com/index.php?route=product/product&path=38_103&product_id=276
freewheel http://tncscooters.com/index.php?route=product/product&path=63_114&product_id=389
 
These are not the droids you are looking for.


:mrgreen:
 
Why does everyone have the need to shift under power? Even when riding a normal pedal bike, you should let up a little to get a nice smooth shift. I find just the momentum of the gears and chain turning often are enough to shift between gears after I let up on the throttle. I roll back on nice and smooth to let the drive train catch up with the speed of the wheel and when I feel it take up, then I get on it. It is pretty easy and you can learn the feel very quick. Without a slipper clutch, the drive chain just can't take it.

Anyway, my 2 cents. Bee, hope you get it sorted soon.

Clay
 
flyinmonkie said:
Why does everyone have the need to shift under power? Even when riding a normal pedal bike, you should let up a little to get a nice smooth shift.
Click to expand...

True. Not letting up on the power when shifting derailleur gearing is like not using the clutch when shifting a manual car transmission. You can do it, but it's a bad idea. Actually, derailleur shifting is a lot like clutchless shifting, and doing it under power is like clutchless shifting under power....

I do feel like pointing out that the NuVinci hub has the advantage of always being in gear. It resists shifting under power, but shifting is not an event per se. It's "in gear" throughout the process. And the N171 (old) version is actually rated for the kind of power that most of the GNG-busting crew use, or aspire to use.
 
LightningRods said:
speedmd said:
The tooth profile is clearly not like the GT. The GT has tooth walls do not go parallel toward the tip as on the HT. The pulley teeth look clearly more like the HT to me. Has anyone put a belt against it to see if the tooth on the belt bottoms out as in the red-lined outline.
Click to expand...

I'm starting to think you're right, Doc. I did clamp a HTD on it and while the fit wasn't perfect, it wasn't far enough off to be a completely different belt type. It's a sloppy HTD with an odd flat bottom to the profile. It's all Thud's fault! He started this! :p

I just bought this pulley to check my own digital profile anyway. This pulley is only 19mm wide and I want a 23mm wide to run a 20 mm belt on. I'll make some subtle adjustments to the profile to make it fit the belt better and then have a prototype made.
Click to expand...

Agree, it needs to be made better. Looks to me like they added clearance at the root of the teeth so it could also run a square tooth belt. May have a bit more backlash but would go with it if the pulley tooth bottoms out in the belt.
 
speedmd said:
Agree, it needs to be made better. Looks to me like they added clearance at the root of the teeth so it could also run a square tooth belt. May have a bit more backlash but would go with it if the pulley tooth bottoms out in the belt.
Click to expand...

The pulley tooth doesn't bottom out in the belt and the sides of the belt tooth don't make proper contact with the sides of the pulley either. The only place that solid contact is made is the bottom of the round HTD belt profile on the too shallow, too flat profile of the pulley. It's not a GT pulley but it's not a proper HTD pulley either. A shame. The finish is nice.

SDI_18T_Belt-Teeth.jpg
 
Awesome! If these work out, it might be useful to find a metal central interface. The pic shown is the 6-hole Kart chainring for Extron sprockets. I recently found out that they chose 6 holes instead of 5 or 4 because 6 allows the chainrings to be made in two half-moon sections (if you want), and that allows the chainring pieces to be swapped out without removing the central spider.

219Extron.jpg

images
 
It should work great if you use ABS plastic and find a decent way to mount it to the motor shaft. The 10mm shaft won't work with plastic.

PLA is supposedly better for plastic on plastic gears, and is self lubricating, but I don't know if it would be mechanically strong enough.

The source code to those gears is at http://www.thingiverse.com/thing:10707 if you want to change size and gear ratio parameters.

LightningRods, did you try casting those pulleys I sent you?
 
What do you think guys? will it hold up for the GNG-forces?
Click to expand...

Put them on your new build, Christer. I want to hear what kind of sound they make at 88V! :mrgreen:

LightningRods, did you try casting those pulleys I sent you?
Click to expand...

I haven't, Bee. I'm involved with buying a lathe this week and still trying to figure out whether I want to go with cast resin or zinc-aluminum alloy for the pulleys. How are the pulleys working out for people? Are they holding up?
 
Someone who ordered my primary adjustable sheets just sent me this picture of the "New and Improved" Gen 1 GNG. They didn't make the sheets adjustable but they did change the design and eliminate the alloy bearing blocks that held the old design together. I'm asking the member to send the upper sheets and jackshaft to me so that I can see what modifications I have to make.

Couldn't they leave bad enough alone?

G-N-Jackass.jpg
 
LightningRods said:
just sent me this picture of the "New and Improved" Gen 1 GNG
Click to expand...
You'd have to wonder why? I guess it's a good sign that someone is "trying" to improve it. :shock:

My GNG is still going well, except the belt started to slip on the last ride after several hundred kms. I'm doing a dodgey with it and have put it back on the reverse direction, it'll be interesting to see how long it lasts now. :D

...
 
full-throttle said:
Interesting mod to the bearing block. Looks like some sort of bottom bracket..

Back to #25 chain strength. It's always possible to double up the chain.
Click to expand...

That's pretty clever. When diameter is the issue, double up. Going from 15mm wide belt to 20mm wide belt is sort of a similar idea.

The Conway is an interesting bike. $7,000 Euros which is about $9,000 US. It has a 1kW motor. I'm thinking the top half of the class here at E-S could build a mid drive that would whup their butts for about $2,000 US. It just reinforces the old saying, "If you think an education is expensive, try ignorance."
 
skyungjae said:
That design looks like it would be more sand resistant... I want this.
Click to expand...

The tube may help keep water and crud out of the bearings. Both the driven pulley and freewheel sprocket have to be removed now to disassemble the upper sheets. I'll have to wait until I get my hands on one of these to see if it can be adapted to the existing adjustable sheets or if a complete redesign is needed.
 
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