Nuvinci with a GXH50 on a USX

cgbjake

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Well, I've convinced my wife that she will be able to ride the USX easier with a Nuvinci and she allowed me to buy the hub. I purchased the trike a month or so ago and haven't really rode it except for around the nieghborhood. I'm taking the project slow and figured if I'm going slow, may as well do it right. I'll be using the non-driven wheel to attach the drive sproket and use the Nuvinci hub as a jack shaft. I'll mount the output sproket to the disk brake mount and will have a free wheel on the Nuvinci so the motor can free wheel on the hills. People have said that because they have a transmission that they went with the GX35, but I think I'm sticking with the big 50, unless of course anyone can give me a reason not to. Only the hub is in the mail, so I have time to change things around. If anyone thinks this will be a bad idea, please let me know. I'll post pics as I go, but that may be a little while. For now, the only thing turning are the gears in my head!:-/
 

vegaspaddy

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hi cgbjake,

good luck your build, i am adding the same engine on my wifes ez3 ax trike, but its a friction drive ,just to help her pudder around with the kids in tow.
 
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Hardcarve1

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The only thing I would say is the 50 is a bit heavier than the 35 and the NuVinci already has some weight to it. I have both and do like the lightness of the 35 and the better throttle response but will be mounting the 50 on in a few weeks time. The govenor will be removed of course.

I think you will end up with a great ride.

Alex
 
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Irish John

Guest
Well, I've convinced my wife that she will be able to ride the USX easier with a Nuvinci and she allowed me to buy the hub. I purchased the trike a month or so ago and haven't really rode it except for around the nieghborhood. I'm taking the project slow and figured if I'm going slow, may as well do it right. I'll be using the non-driven wheel to attach the drive sproket and use the Nuvinci hub as a jack shaft. I'll mount the output sproket to the disk brake mount and will have a free wheel on the Nuvinci so the motor can free wheel on the hills. People have said that because they have a transmission that they went with the GX35, but I think I'm sticking with the big 50, unless of course anyone can give me a reason not to. Only the hub is in the mail, so I have time to change things around. If anyone thinks this will be a bad idea, please let me know. I'll post pics as I go, but that may be a little while. For now, the only thing turning are the gears in my head!:-/

Your trike project reminded me of a conversation I heard yesterday whilst mashalling in a MTB endurance race. Some riders were talking about a new 4 wheel drive shaft-driven pedal cycle that could go over all sorts of terrain. Does anyone know about this invention - I think it's a small invention by some guy in Britain?
 

cgbjake

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Gearing question

OK, this awesome piece of engineering arrived today. I'm very excited to get this thing mocked up and finished. I built a cardboard box for the engine and rough figured where it will be placed on the bike and how the Nuvinci Hub will line up. I think I have a pretty good idea how to make it look pretty good.

The current gear ratio I have figured out it this:
20" wheel
7000 RPM engine ( a little more is max, want to stay off the red line)
Drive gear will be 11 teeth
Jack shaft input (input to Nuvinci) 60 - just over the diameter of the hub
Jack shaft output 14
Final drive 40 (I'm limited to this diameter because of bike design)

My figures give me a max speed of 26.7 MPH.

With the Nuvinci hub in overdrive, I should be able to comfortably pull in the high 30's but don't know how to figure out the theoritical max speed. And if the Nuvinci is in underdrive, what the max speed would be there.

If anyone can find an holes in my design plan I'd love to hear it. I'd like to do this once and I'm all about learning from other peoples mistakes. Please share your ideas if you have them.

I'll post some pictures soon!
 

cgbjake

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Here is a gearing answer to my question, but I don't know how to figure in .5 and 1.75. I'm a little slow with the math thing, can someone show me the equation?
 

cgbjake

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Parts arriving daily and I'm getting excited to get on the lathe to turn down the new shaft. Thanks to GoblinAreo for hooking me up with the details. I have yet to purchase the engine (have save just a little more) but I should have a lot of the mock up done in a few weeks...as long as life doesn't get in the way!
 

vegaspaddy

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yeap, my bikes are my escape from the mad world we exist in, never a dull moment in this household, outnumbered 4 to 1 by the ladies!!!!!
 
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duivendyk

Guest
I am trying to make sense of what you intend to do.you are driving the NV on the right side from your engine with an 11/60? chaindrive ,(60t sprocket same size as the hub??).This would be a freewheel.Then on the output of the NV mounted on the disk brake adapter you have a 14t output sprocket (can you mount anything that small there?, going to a 40t on the wheel.Assuming for the moment the NV to be 1:1,we have an overall ratio of
(60/11)x(40/14)=15.6.Roadspeed= .06 x rpm/R, R is the drive ratio.At 7000 rpm we get 0.06x7000/15.6=26.9 mph which is pretty close to your number (26.7).If you throw in the NV ratio
2-0.57 , from a reduction of 2 via 1 to 0.57 (1/1.75),we get a low speed of 13.45 mph and a top of 47 mph at 7k rpm.At 5k we get
9.6 and 33.6 mph.The NV hub will be running at far,far higher rpm than it's intended use as a bicycle hub, close to 1300 rpm it is designed for 200/300 rpm but at higher torque.There is a special friction fluid in there, Who knows how the thing behaves at 4-5 times normal rpm??.(centrifugal effects??).I advise you to contact David Staton,he has been playing around with these hubs as intermediate drives and may have useful info.Also are a 60t sprocket at the NV input & 14 t output practical?.
 
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