What kind of rear sprocket needed for a NuVinci hub with SBP shift kit?

Discussion in 'Motorized Bicycle General Discussion' started by Cannonfish, Dec 18, 2009.

  1. Cannonfish

    Cannonfish New Member

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    Hello all,
    So I took the plunge and ordered an SBP shift kit and a NuVinici rear hub! The shift kit was a joy to put together and install, and now I'm lacing the NuVinci into a wheel. I noticed that it didn't come with a sprocket on the right side, however, and now I'm a little confused about what kind of sprocket I need.
    There is a threaded "adapter" that came very firmly installed on this hub's standard-looking splined freewheel connecter. I can't manually get that threaded adapter off (maybe it's actually part of the hub itself, but it looks like it was just slid into place over the splines).
    So my question for any of you guys who are running NuVinci hubs and shift kits is, what type of sprocket are you using? How many teeth - and if, you're using a threaded sprocket, are the threads "metric" or "english"?
    Below I'm pasting a link to the sprocket I *think* I need... note that it is actually a freewheel (alternatively, could I use just a simple sprocket without the freewheel part built in?). The options I picked on this page were 17-tooth English threaded:

    https://www.universalcycles.com/shopping/product_details.php?id=7023&category=402

    My set up is: 67cc Skyhawk with expansion exhaust pipe and some minor porting, running a 10-tooth heavy-duty SBP shifter kit on a Micargi beach cruiser frame with 26" wheels.
    Thanks for your advice, and I'll put some pictures up soon!
     
  2. Maxvision

    Maxvision New Member

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    Interesting that you have a rear hub with no gear on it!

    Here's a link to a website that has a info and links to info on calculating gear sizes. Hope you're a educated person cause my eyes started spinning in opposite directions trying to understand that stuff.

    ATC NuVinci Continuously-Variable Bicycle Hub (Internal-"Gear")
     
    #2 Maxvision, Dec 18, 2009
    Last edited: Dec 18, 2009
  3. Cabinfever1977

    Cabinfever1977 New Member

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    you will want to use a freewheel. if you use a standard sprocket your peddals will turn all the time, even when coasting.
    Most hubs that you buy will not come with the freewheel sprocket and you need to buy it separately, and they usually tell you which one to buy.

    I forgot the peddal has a freewheel on it already cause its a shift kit.
     
    #3 Cabinfever1977, Dec 18, 2009
    Last edited: Dec 20, 2009
  4. Maxvision

    Maxvision New Member

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    The SBP shift kit comes with a freewheel for the pedal sprockets.
     
  5. POPS

    POPS Member

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    Hi Cannon and welcome to the form.

    I would really like to see a close up pic of that threaded adaptor on the NuVinci hub.

    I bought a used one with what looks like a new freewheel on it and the adaptor

    has about a 1/4" play side to side...POPS
     
  6. POPS

    POPS Member

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    Cannon...I would ask the guys at SBP.

    I know if it is going off the peddle crank it is supposed to be half of

    what it is ...EG: 36 tooth front, 18 tooth rear, But with the shift kit??...POPS
     
  7. Cannonfish

    Cannonfish New Member

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    Thanks to everybody for their thoughts!

    Pops - here is a picture of my freewheel adapter (notice no freewheel on there yet, I've decided to try a 16-tooth but still waiting on the mail). It's very solid - the adapter, splines, and hub all feel like one piece. I did some looking around online and found out that the interior diameter of an English threaded freewheel is 1.37 inches - this is exactly what this adapter measures over its threads. If yours has some play in it, maybe you could contact NuVinci (Fallbrook Technologies) to ask about a replacement adapter?

    Let me know how your install goes - I keep getting sidetracked but hopefully I'll be able to get this one up and running in the next week or so.
     

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  8. Cabinfever1977

    Cabinfever1977 New Member

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    That threaded thing on the hub is a adapter for a freewheel sprocket and it should come off,after taking off the adapter you can slide a non freewheel sprocket on the spline of the hub,heres a link.
    Results Page

    If you want to use that adapter or cant get it off you will need a freewheel(i think) sprocket that screws on the hub.
    Results Page
     
    #8 Cabinfever1977, Dec 20, 2009
    Last edited: Dec 20, 2009
  9. scooter09

    scooter09 New Member

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    Staton Inc. sells the sprocket you need
     
  10. Ghost0

    Ghost0 New Member

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    An 18 tooth freewheel is what most people seem to like but it all depends on your riding, engine power etc. I think the 16 will work. Unless you are doing a lot of off road riding where a very low gear is required I think you will be fine.

    One thing I think would be neat to try is using a fixed cog as was mentioned in the previous post. The front freewheel allows for this. It will also give the ability to bump start which with a standard derailleur and rear freewheel is not possible.
     
    #10 Ghost0, Mar 18, 2010
    Last edited: Mar 18, 2010

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