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

[Joe T.]

I'm glad to see others having the chain skipping problem in the upper gears. I too have been dealing with this with both my bikes. Both have home built rear swing arms that I was blaming for this issue. I recently shortened my chain 4 links which helped a lot on the skipping. Still I need to feed the throttle slowly from gears 6-9, but it has improved greatly.

I was researching the chain drive update after I wiped out the original belt. I bought the belt from Amazon listed somewhere on this thread and it had been doing well. I'll wait it out to see if the upgrade is needed.

 

[kifukarider]

Thank you for your input guys. I'm running really cheap components that came with my original rust bucket bike and a 14t-28t freewheel rim that I got from a 26" girls bike. :lol: I've really put all of my investment in the electronics. I hadn't read any messages about chain skipping, whereas belt skipping posts were common. I now wonder if chain skipping is actually more common than realized. Good info on the SRAM X7 derailer. Since shortening the chain seems to have solved the skipping, I'll leave as is for now.

 

[bee]

The DMR STS single speed conversion kit with a BMX chain gives me plenty of tension and doesn't skip when going WOT to 7000w

http://www.ebay.ca/itm/DMR-STS-and-Cassette-Spacer-Combo-Kit-/171122824686

 

[1KW]

had another dumb question...I have a SS mtb. Can I just run the single gear in the rear, 16t, and make it just shift the front derailer chainrings? A 3 speed upfront, with say a 18-20t in rear? I dont really need 7-9 gears if It can be swapped with just a front derailer.

 

[deepfraught]

Yes you can do that, but you will have to have zero throttle and no load on pedals as you pedal lightly to change gear.
Front derailleurs are not made for shifting under load, I'm sure there are exceptions like Di2 or others in the past.

New question: what bottom bracket can I use to ditch the stock one?
Bikepedia says I have a TruVativ Howitzer BB on the A-Line, and it doesn't fit.

I read Full Throttle said a Holzfeller or Hammerschmidt BB for external cups.
Has anyone confirmed those, only other mention I've seen in search was about BB replacement was with Cyclone freewheel cranks?
(can't search for BB so search for bottoms

 

[1KW]

I just think that running a BMX chain, a solid rear gear(straight easy chain line) and 2-3 chainrings up front could make up for the rear gear cluster.

Who knows
Gear 1= 0-20mph
gear 2= 20-28mph
gear 3= 28-35mph

with a straight rear chain line, and a no rear derailleur to break. Only issue would be keeping the gears somewhat close in size up front for easy shifts, and to no throttle it on a quick shift. I would also run this on 60-80v lower amps.

I want to drive this bike on the road..in traffic, and wouldnt mind scooting off the line 3x faster than cars. However a hub at 100v would do this...but I think middrive will be way more fun if you can get it somewhat maintenance free other than routine maintenance.

 

[--freeride--]

I just think that running a BMX chain, a solid rear gear(straight easy chain line) and 2-3 chainrings up front could make up for the rear gear cluster.

Who knows
Gear 1= 0-20mph
gear 2= 20-28mph
gear 3= 28-35mph

with a straight rear chain line, and a no rear derailleur to break. Only issue would be keeping the gears somewhat close in size up front for easy shifts, and to no throttle it on a quick shift. I would also run this on 60-80v lower amps.

I want to drive this bike on the road..in traffic, and wouldnt mind scooting off the line 3x faster than cars. However a hub at 100v would do this...but I think middrive will be way more fun if you can get it somewhat maintenance free other than routine maintenance.

You will need a rear detailleur with 3 Chainrings in the front! otherwith you wont get your chaintension right.

 

[1KW]

well, ill run a heavy duty singlespeed tensioner in rear.

 

[LightningRods]

Hey Gang-

Sorry to have been absent. I've had an incredibly busy few weeks. Here are my updates:

I worked for a month straight to get a 'big block' motor with fan shipped through Mister Tao. They refunded my money (put it back in their holding account under my name) TWICE because vendors did not deliver the motor. I tried a third time, waited two weeks to the day and finally the motor arrived at their shipping dept. I should have the motor in hand by next week. Kin Fong and I are going to build a monster FS bike with it.

As you can see from the price breakdown it's the shipping that kills you from China. I've put together a deal to get pallets of the standard width, 2700 gram Honglida or 'GNG' motors shipped slow boat from China. It's a chunk of change though because I have to buy 20 of them.

I beat on my machinist and finally got a run of 11mm shaft to 3/4" bore steel adapters out of him to adapt 12 tooth #219 drivers to the secondary side. I'm now ordering the 12 tooth 219 sprockets and will weld them to the adapters. The BB adapter plates have been available for several weeks so the 219 secondary conversion is open for business. PM me if you want 66% more reduction on your secondary drive. My neighbor ran 25 horsepower through 219 chain for years in his kid's race car and said he never broke one. It's awesome chain.

I keep fussing with the GT2 belt drive because I want it to be perfect. The crappy belt drive on the stock GNG is SO bad I feel like I need to solve all of the problems on the first try. I've found a Gates distributor within driving distance and I'm going to take all of my parts and drawings over and make certain that I can deliver a finished system with the correct pulleys and belt, all within spec. There is a very good chance that I will go with 25mm wide belt instead of 20mm. 15mm and 25mm are the standard widths. 20mm has to be cut down and will be harder to source. I've settled on 90 teeth because the smaller overall pulley diameter will engage more teeth in the driver pulley. With the 120 tooth only six teeth were engaged, almost as bad as the stock GNG's 14/80 ratio. With 18/90 there will be seven, close to eight engaged. My top priority is that this drive not skip and not wear out belts. We can get more reduction back on the secondary side. I've also designed in a mount for a ACS or W-I freewheel. This CAD model is ready to go to the service bureau for printing.

Oh, and I'm also ordering ten of the 148mm Cyclone/Truativ ISIS BB sets. Four sets have sold already and I want one for my own bike so they are half gone.

If you're interested in these parts shoot me a PM and encourage me. I'm spending money like a drunk sailor and it gets intimidating at times.

Thanks,
Mike

 

[--freeride--]

well, ill run a heavy duty singlespeed tensioner in rear.

I tried that allready an it did not work out on my bike. The chaintensioner has a to short swingarm for that. if you stay on 2 chainwheels up front it might work. With 3 chainrings you need to mod a normal rear detaileur.

_________________________________________________________________

@Mike: Very very nice! A monster of a motor. 25mm belt and that Motor will be a tight fit!

_________________________________________________________________

I just did some calculations:

First Stage 25# chain:
Motor| Bat| first stage 25# Chain| secondary 219#chain| Chrank rpm
67kv* 96V/ 80*11/ 90*12 = 117.9200

So you can go up to 100V and still be able to be pedaling with Mikes secondary 219# conversion!

Mikes Belt mod:
Motor| Bat| first stage GTS belt| secondary 219#chain| Chrank rpm
67kv* 96V/ 90*18/ 92*12 = 167.7913

Motor| Bat| first stage GTS belt| secondary 219#chain| Chrank rpm
67kv* 72V/ 90*18/ 92*12 = 125.8435

Even with belt pedaling will be fine on 72V

 

[1KW]

I wonder how a 2 ring upfront would work, with the ss in rear. anybody have gearing calculators to see what speeds I could Net. Probly do it with Higher voltage to get more speed...

 

[--freeride--]

I wonder how a 2 ring upfront would work, with the ss in rear. anybody have gearing calculators to see what speeds I could Net. Probly do it with Higher voltage to get more speed...

I would try 3 gears in the rear with proper chainalleinment and a minimum of 13T or even 15T.
That combined with a short cage rear detaileur with a strong spring and an high quality shimano 8speed chain should work pretty good.

If you ride 34T, 22T and 15T in the rear for example that is even better than 3 gears up front.
You might alltough want to use bigger gears at all, so you keep the mechanical stress abused to chain and gears lower.

So better go to 42T(custom chainwheels available),34T,22T in the rear instead and chainskipping should not be a problem...

 

[spinningmagnets]

If you overpower an external derailleur gear-set, the chain will simply skip a tooth or two. If this damages the sprocket or the chain, they are both easily sourced and fairly affordable to replace. A spare wheel is very affordable to keep in stand-by for such occasions when someone is experimenting with max power limits after an upgrade.

I am quite fond of Internally-Geared-Hubs (IGH), but if you break a tooth, an IGH would be more expensive and time-consuming to repair/replace.

Once someone determines the gear-ratios that satisfy your goals in a build, the best move (IMHO) is to use the largest sprockets that will achieve that. This will spread the load over more teeth, and it will also allow more load to be applied before tooth-skipping (or tooth-breakage) becomes an issue.

This is why designing from the very start to have as much motor-reduction as physically possible is the right move. You can always gear-up with the chainring, and after the chainring has been enlarged as much as possible, the rear sprocket cluster can then be enlarged up to the point where your most-desired gear-ratio limits are not exceeded. The end result is the maximum possible number of teeth engaged with the chain. Longer chain and sprocket life, higher power application without breaking anything, and...even just a few extra teeth (and the larger diameter that is included), will make the drivetrain run quieter.

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

There is also the consideration of adjusting the phase/battery amp ratio. By adjusting this (when using a controller that allows phase amp adjustment), you will have full power at top-speed, but...when starting out from a stop, the maximum amps will be dialed back a bit. This eliminates the ability to "wheelie" when using that setting, but...it also reduces the amount of stress on each tooth.

 

[Denisesewa]

I have been using a 9 speed cassette with a 3 speed x-9 shifter and 9 speed x-9 derailures on both my bikes set up to shift two cogs at once, along with adjusting the controller as spinningmagnets stated and the chain conversion/ lower ratio primary, This has been bullet proof so far , much cheaper to install quality components to begin with than deal with replacing parts , also a front chain guide has eliminated any chain derailment issues. I still have tons of power to wheelie anytime I want and the Magura throttle/ Lyen controller allows for precise throttle control. I find 3 gears is all thats really needed. The key to setup is adjusting the derailiure for as much chain wrap as possible with the shortest chain possible and the jockey wheel as close to the cogs as possible, I have one medium cage and one long cage they both work great.
This has been gone over before but is buried in this thread so thought I'd post it again.

 

[LightningRods]

@Mike: Very very nice! A monster of a motor. 25mm belt and that Motor will be a tight fit!

The beastly FS bike that Kin has seems to have an 83mm BB. He measured between the crank arms and there's over 7 inches of space. This brute bike and that brute motor were made for each other. We haven't even started on the build and I want one already.

So you can go up to 100V and still be able to be pedaling with Mikes secondary 219# conversion!

My thought is that most of the completely mad overvolters (you know who you are) will be less worried about noise than those of us who ride our bikes on public roads and bike paths at something resembling legal speeds and power limits. I'm targeting my GT2 drive at the latter. I will be really interested to see if the 2.7kg 'small block' can handle enough watts to skip a 25mm GT2 under any circumstances. I'm thinking something else will break first. That is my goal: to build a primary belt drive which, if you are foolish enough, will break your bicycle before it breaks.

I'm liking the three speed rear cassette- a lot. I was pondering the idea of three custom cassette cogs that were as wide and strong as the drive chain will allow with two thin 'ramp' cogs in between them that did nothing but assist in the jump between gears. Denise has answered the main question that I had, which was adjusting the derailleur properly so that it indexes to the drive cogs and not the ramps. I think this mod to the conventional bicycle cassette would be exactly what e-bikes need: fewer gears with more power capacity.

 

[spinningmagnets]

14T-28T Shimano five-speed splined freehub (perhaps a threaded freewheel exists too?)

 

[LightningRods]

Here's a 25mm GT2 belt next to the stock GNG 15mm HTD:

Here's Gates Corp's quick fact sheet on the GT2:

 

[LightningRods]

14T-28T Shimano five-speed splined freehub (perhaps a threaded freewheel exists too?)

That's definitely heading in the right direction. The unfortunate trend right now in human power only bikes is towards more and more gears. We don't need all of these extra gears and we definitely don't need the thinner cogs that go with them. A five speed hub with three heavy duty drive cogs and two shifting cogs could be perfect.

I need to find an open-minded and creative bicycle mechanic here locally. Most of the mechanics I've tried to talk to so far are pedantic parts swappers that become visibly uncomfortable when you talk about 'creating' anything.

 

[Denisesewa]

Keep in mind that you will have to modify any high end derailiure to accomadate heavier ( wider) chain that those wider cogs will require.

 

[spinningmagnets]

These $40 adapters are splined on the ID to slip onto a common Shimano freehub. They accept 74-BCD chainrings with tooth-counts from 24T to 32T (one chainring on each side?), and for the smaller third sprocket, splined track cogs are available from 12T-22T. (16T/24T/32T?)

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7192#p198285

 

[1KW]

awesome! A rear 3 speed would be perfect seeing that less shifting=good, and if they are geared enough apart, but close enough for a easy shift...

Seems like the front chainring idea is bad, but curious on this rear setup. I actually have a ss mtb rear wheel, but curious how to fit only 3 rear cassette cogs on it and make it work. i have the lockrings that come with it, and i just have spacers on both sides of the single gear. With 3 efficient gears, I could just only use 1 spacer on each side with the lockring on end. The only issues I see is setting up a detailer to work with it(easy, just alot of fine movement tuning), and gear wear on 3 gears vs 9. However with 3 you could get the best gears out of the kit, and not mess with those "shifting" gears.

 

[Whiplash]

I thought I would post that my two brothers just ordered a GNG style kit each! One us replacing a MAC that was running about 2k watts peak, and the other is an E bike noobie! So I have converted another one! Lol. The first bike will be running 15ah of 12s LiPo, the second is using two 8000mah packs from HK also at 12s. This one I am going to make a simple batt box that will latch into the frame to be quickly remove able for charging. I'll start a build thread for it and update an existing one for the bigger build..

Oh by the way, these are coming directly from Conhismotor, do you can see how their kits stack up against the GNG. I got them for $403.01 shipped DHL so pretty good considering the speedy ship should only take about a week..

 

[1KW]

whiplash, the kits are probably IDENTICAL(same chinese supplier).

We need to find this supplier to ship directly to us...!

 

[Tinto]

LR those belts and pulleys are looking like a great upgrade.
Do you foresee any crank arm clearance issues with the additional few mm?

14T-28T Shimano five-speed splined freehub (perhaps a threaded freewheel exists too?)

Even though I see gears and some bevels, that doesn't look shift-friendly - is it intended to be?
(Compared to the usual pinned / ramped setup)

I've gone single speed + tensioner on the rear of my GNG setup, but would gladly use a davinci if I could justify the cost.

 

[kifukarider]

My adventures with cheap components continue.

I got a flat which gave cause to take a closer look at my rear wheel which was in serious need of attention. My rim was quite wobbly and my freewheel sprocket runout had greatly increased. It turns out, I had a flat, bent axle, broken spoke and during rebuild discovered a failed bearing. Some of the other bearings showed some minor scarring from the failed bearing fragments, but not too bad.

This all happened while running on the chain drive GNG at around 3000W. I think I had a too much slack in the axle which caused the bearing to fail. The axle may have been victim to the same. The flat was just a piece of staple picked up from the road.

I reused the axle since I don't know where to source one on short notice. I replaced the failed bearing, cleaned thoroughly and regreased. I tightened the axle to where I got relatively smooth rolling, but very solid cogging. When I replaced the failed spoke, I was amazed at how much truer the rim became with out much tuning. I reinstalled the wheel with the bend opposing torque so maybe it will get straightened back. :lol: After patching the tube, I'm now back on the road, no harm done it seems.

I'm going to roll on this wheel until I figure out my next upgrade. I think I'm leaning toward a strong freehub with something like 7 speed 12t-32t.