Nexus 3, 4, 7 or old Sturmey Archer?

Discussion in 'Hubs, Gearboxes, Sprockets and Chains' started by Tomasito, May 24, 2011.

  1. Tomasito

    Tomasito New Member

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    Hello,

    I'm in the proccess of making a custom motorbicycle, and I plan to use a internally geared hub.
    I live in Argentina, so I don't have many options.

    First of all, it HAS to have rollerbrakes or discmount because my rim doesn't allow me to use rimbrakes. I don't know any other brake that isn't coaster or v-brake type, excluding disc but i could not find any geared hub for discbrake. (In Argentina)

    I could find some old and used SA very cheap, but i don't know if they will hold up. I've read that they don't, buy maybe the old ones was better constructed? Someone knows?

    On the other side, a local bicycle shop has a Nexus 7 w/ coaster brake (used). I was going to buy it but the guy said that he thinks it's broken or misadjusted (he will check it).

    And also i've emailed and called arround 15/20 bicycle shops in my country, and one has a Nexus 8 without brakes (maybe I could put a rollerbrake?), and other guy told me that they could get the 4 and 7 speeds.

    My best bet is the 4 speed with a rollerbrake, but i'm not sure if they ever existed (maybe they came only with coaster brakes?). And, would they hold up? I read that the 3 speed won't and the 7 will, but i don't know about the rare 4 speed.

    The nexus 8 is a nice option, but it costs 250$ and i would have to add a rollerbrake (that i'm not sure if i could find it).

    Shimano alfine, Sram, sachs, new SA and all other are discarted because none sell them.

    If someone wants to follow my build log, go to Born to be Freak

    Thanks in advance, I will super appreciate any help.
     
  2. silverbear

    silverbear The Boy Who Never Grew Up

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    I don't know how you intend to set up your jackshaft, but I would suggest looking at the one offered here by one of our vendors, Sick Bike Parts. With theirs you can use either a deraileur setup or an internally geared hub. With their kit you can not use a coaster brake type of hub... it has to be freewheel. I'm going with a three speed Sturmey Archer. They also have a 5 speed and an 8 speed. Why not order from outside your country and get exactly what you want and what will work easily for you?
    SB
     
  3. Tomasito

    Tomasito New Member

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    I will make something like this: http://motorbicycling.com/f3/integrated-motor-mount-jack-shaft-12284.html
    The SBP is really out of my reach, it costs as a new geared hub.
    I don't really have a problem machining and making parts, i've a big shop.
    So if I can make something, i can save a lot of money, and make it exactly as i like.

    Also, i can't buy outside Argentina because i don't have an international credit card (you can't buy outside argentina without one). Also the shipping would be ridiculously high.
    Even if I could send the money via western union and get a cheap shipping, the customs would charge me 50% of taxes (that's the actual value), and that's if the package doesn't gets stolen in the mail.

    So, I have to search inside my country, and mostly used parts :(

    Will you use a new SA 3 speed or a old one? I only can get old and used ones. Tell me how it works for you.
     
  4. WPadgett

    WPadgett New Member

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    * #5 * *
    Today, 11:02 PM

    WPadgett
    Motorized Bicycle Newbie
    *
    Join Date: May 2011
    Location: Bloomington, IN
    Posts: 4
    Re: Grubee HD Axle Kit
    Hi I'm thinking of buying a grubee HD Wheel and I was wondering if it was possible to install shimano roller brakes on it instead the band brake that comes with the wheel.

    Thanx
    Will
     
  5. Tomasito

    Tomasito New Member

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    Sorry i don't really understand your message.
    If you wanna know if you can put shimano rollebrakes on anything else, i don't really know, but i doubt you can.

    I forgot to mention that i'll use a 48cc chinagirl, and that i cannot use a deraileur because my rear wheel is 20'' x 3'', wich doesn't leave me with a lot of space to play with (and also i don't want a deraileur sticking out of my frame :p).
    I can have it as my last option, but i don't think i could fit it without making the rear fork really wide.
     
  6. camlifter

    camlifter Active Member

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    make sure the hub you go with has some under drive gearing, as in 1st and maybe 2nd gears beinging under drive. a lot of the internal hubs start out as 1-1 ratio and go up as over drive for all the higher gears. the china girl is probably only going to have the power to pull only one gear ratio above 1-1. the more under drive gears the better. the S/A 3 or 5sp hubs have proven they can hold up to a china girl.
     
  7. Tomasito

    Tomasito New Member

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    Well, i sent the old SA's guy an email asking if he has one with a drum brake.

    It seems that all SA 3-speeds are undergeared at 1st, direct drive at 2nd and overdriven at 3rd.

    If you say that the old sturmey archer will hold up, I take your word!
     
  8. Zman

    Zman New Member

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    Tomasito, camlifter is right ! The old S/A hubs are really durable, i'm using an old drumbrake-hub in front and it works great !
     
  9. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    QUOTE=Tomasito;287329]I will make something like this: http://motorbicycling.com/f3/integrated-motor-mount-jack-shaft-12284.html
    The SBP is really out of my reach, it costs as a new geared hub.
    I don't really have a problem machining and making parts, i've a big shop.
    So if I can make something, i can save a lot of money, and make it exactly as i like.

    Also, i can't buy outside Argentina because i don't have an international credit card (you can't buy outside argentina without one). Also the shipping would be ridiculously high.
    Even if I could send the money via western union and get a cheap shipping, the customs would charge me 50% of taxes (that's the actual value), and that's if the package doesn't gets stolen in the mail.

    So, I have to search inside my country, and mostly used parts :(

    Will you use a new SA 3 speed or a old one? I only can get old and used ones. Tell me how it works for you.[/QUOTE]

    With skills and a big shop, you could make your own shift kit.dance1

    Bicycle chain, chainring sprockets, bearings and mainshaft should be easy to find for you. Unsure about 17t, 10t or 9t sprockets, or freewheel and threaded crank arm.

    SA three-speed ratios would work well enough, although a seven-speed hub would be more desirable, as far as mechanical leverage is concerned.

    Are you concerned mainly with climbing steep hills or high speed on flat ground? With a three-speed hub, you need to choose between hill-climbing or not. With a seven-speed hub, you can have the best of both hill-climbing or cruising at high speed.xct2
     
  10. Tomasito

    Tomasito New Member

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    My town is super flat, I just want to take off without pedaling if it's possible, and maybe a little more speed.

    By the way, I bought a Sturmey Archer AW 3-speed from the 80's.

    I had some troubles finding the right spokes so for today I will have my wheel laced finally.

    Thanks for the feedback, through!
     
  11. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    Okay, here's a start.

    Your hub prolly has .75:1, 1:1,and 1.33:1 ratios. For flat ground take off and good top speed, final ratios of 14.81:1, 19.75:1 and 26.27:1 should work. They are equivalent to single rear sprockets of 36-tooth, 48-tooth and 64-tooth cogs.

    Your engine has built-in gear ratio of 4.15:1. You need a pedalling ratio of 2:1, like a 36-tooth chainring sprocket and an 18t on the hub. That means you need to develop 9.875:1 more gearing.

    If you use SBP's 17t mainshaft sprocket with the engine's 10t sprocket, that's 1.7:1. Using a 10-tooth jackshaft sprocket with a 56-tooth sprocket gets you 5.6:1.

    Multiply 4.15 x 1.7 x 5.6 x .5 = 19.75:1
     
  12. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    This is a set-up I'm currently building that will use the Shimano Nexus 3-speed hub with a disc brake.....it's all new components and I'll let you know how it holds up after some serious testing. It will be powered by a 124cc Kawasaki 4-stroke and running 11:1 and 12.22:1 gear ratios depending on the track or ride for a given day.

    [​IMG]

    [​IMG]

    dnut
     
  13. TheRealDune

    TheRealDune New Member

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    How did it hold up scotto
     
  14. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

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    This in an old post from 2011 and it blew up after the first race at Willow Springs go kart track.
     

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