Is the Nexus 3 speed hub strong enough?

Discussion in 'General Questions' started by Douglas65, Nov 30, 2007.

  1. Douglas65

    Douglas65 Guest

    I have been tossing around a few ideas and am wondering if anybody has experience with the Nexus 3 speed hub (like on this beauty: http://www.feltracing.com/08/product.asp?catid=1504,1519&pid=8545). Specifically, is it strong enough to handle the torque from a Honda 50 4-stroke going through the 3 speed drive part of the hub?

    I may eventually just try it and if it fails, move up to a SRAM P5 Cargo (5-speed) hub, built for heavy duty use.

    BTW, when i go through with this, the top bar on the bike will hold gas and look like an old bike turned motorcycle like they all at first were. http://www.motoredbikes.com/showthread.php?t=5510&highlight=three+speed
     

  2. azbill

    azbill Active Member

    I believe that it has been tried and proven that the internal nexus drive can't take the sustained torque
     
  3. locoWelder

    locoWelder Guest

    can you say internal meltdown, it wont hold it!
     
  4. Wouldn't it work if you babied it? I mean at speed,drop the engine rpm to idle,shift,turn throttle back up?
    I wished they would make a 2 speed hub. That's all a motoredbike needs. A climbing gear and a cruising gear.
     
  5. iRide Customs

    iRide Customs Member

    I don't think it would stand a chance in He..L..L.

    A hub that MIGHT work would be the Rohloff 14 speeds, but they're kinda spendy. I'd hate to spend the cash on one of them just to grenade it in 10 min.
     
  6. Douglas65

    Douglas65 Guest

    OK, that changes my plans. Any ideas on the SRAM P5 Cargo (5-speed) hub? Has anyone experimented with this one or is it one of those rare animals that no one has actually seen before?

    Seems everyone has the same problems with motorizing bikes: you can get good engines, and gearing it down low enough seems relatively easy (simple gearboxes, jackshafts with large/small sprockets), but adjusting engine speed with bike speed (gearing) and secondly, transfering power to the rear wheel effectivily both seem to be real sticking pounts.

    I know it can be done. Rokon used a 3 speed transmission http://cgi.ebay.com/ebaymotors/1968...120188928900QQrdZ1QQsspagenameZWDVWQQtcZphoto that I believe works much like a Harley transmission -that is, added in between the engine and the rear wheel. I believe we cold really use something like that if it were available. Thing is, there is probably some Chinese company that makes exactly what we need that no one has even heard about before. And I agree with Large, even 2 speeds would work (but 3 is better).
     
  7. Alaskavan

    Alaskavan Guest

    Last edited by a moderator: Dec 1, 2007
  8. Douglas65

    Douglas65 Guest

    That Nu Vinci hub looks beautiful and beefy! As long as it works as Staton hopes, that would be great. The only draw back would be the cost (?almost $500 with re-spoking, etc.?). The P5 might be half that (I am checking) and still usable.

    I am also thinking about a 2 speed jack-shaft or even a CVT, but they are huge and probably would not fit in the frame easily.
     
  9. FWIW - If there is enough interest on the NuVinci I could get them for us at about $275
    Delivered to you in the lower 48.....Problem is that a jackshaft will still be required...and a
    $25 adaptor piece will have to be added to the hub so that the rider can pedal it as well.

    I have a SRAM 3 speed I was going to try to make work but have been busy lately....

    Later today I may try tinkering with a few things on the bike tho.

    Andrew
     
  10. I've been thinking up a way to build a small two speed tranny with a stick. Up is low and down is high or something.
    Something really simple utilizing the happy time clutch...maybe like two simple gears like in a manual tranny in a car encased in a metal box with gear oil....there's gotta be a way.
    Now couldn't a homemade cvt set up be made like this:
    http://videos.streetfire.net/video/b99f4c8a-5110-45f9-afd2-984800d611a6.htm
     
    Last edited by a moderator: Dec 1, 2007
  11. Douglas65

    Douglas65 Guest

    Another idea.

    I have, and most of us have seen a drill press or mill/drill that has 2 sets of pulleys connected with a belt to change the gear ratios of the tool. Each pulley set has a big, medium, and small pulley attatched to it with a belt going to another set of pulleys that are small, medium, big. This is a very effective and I believe efficient way to transfer power and change gear ratios.

    Switching gears is super easy once the tension is off the belt, and it looks like it "wants" to move to the next pulley much like a chain jumping to the next sprocket on sprocket cluster does. Taking tension off the belt would be easy if we were using an idler pulley for tension.

    Weather you were shifting up or down, you would need to devise some method where the controlls were always making the belt jump to the next smaller pulley, which it always would be, either on the driving pulley or on the driven pulley -depending if your were shifting up or down. It should be a simple mechanism to take the tension off the belt and shift at the same time, kind like Large had in mind with the stick shifter idea.

    OK, looking at what I just wrote, maybe that wouldn't be so easy, but I bet it would work well and be real smooth to drive. Also, maybe the belt tension could be set so that the belt would slip just slightly and therefore go a little easier on all the other components that were never designed to put up with an engine screaming at full bore.:rolleyes:

    Off to search the web for raw materials for this new idea...
     
  12. Douglas65

    Douglas65 Guest

    Also, the Nexus P5 Cargo hub for tandem bikes and cargo/work bikes looks like it is around $130-160 retail. If your dealer can get them. But I was told (by someone trying to sell me a hub) it would work. Maybe.
     
  13. DougC

    DougC Guest

    The Rohloff is quite specific about its torque limits. Somewhere on their website it gives the minimum "normal" sprocket size, and they don't recommend using it with a Schlumph Mountain drive, for the excessive input torque that will result.

    Everyone I've heard of (online) that has a Rohloff, absolutely loves it.
    I've never had one, never tried one, and I'm not real sure I want to.
    That's a BIG chunk of change.... :grin:

    ----------

    I'd think that you could use a hub-gear, but it would have to be as a jackshaft-type drive, off the engine shaft.
    On the golden-eagle setup for instance, the engine cog is about 1" across and the drive ring is about 18" or so. There's not hardly any torque on the engine shaft. You'd wear out the hub's gaskets a lot sooner, but they don't cost much and aren't hard to get.
    (I also like this idea, because it would allow the engine to "freewheel"...)
    ~
     
    Last edited by a moderator: Dec 1, 2007
  14. Sianelle

    Sianelle Guest

    Those wee Albion gearboxes are really nice, but the youngest of them would be quite old now and they're not very easy to find these days. A considerable number were used on various types of self propelled agricultural equipment powered by single cylindered Villiers and JAP industrial engines. They could be found on English lightweight motorcycles too, - usually those by the smaller makers.
     
  15. Papasaun

    Papasaun Guest

    Going back a few months the sheriff was kicking this idea around and even got it on paper? Check this thread out,,,,, gotta read, read, read! :arrow::arrow::arrow:
    http://www.motoredbikes.com/showthread.php?t=5530

    What you are looking for is at the end of the second page. Hope this helps.

    Papa
     
  16. This is what I have in my head. Two belt pulley's split in half length wise mated seperatly and tapered to their own axles. One will have a centrifical spring that will bring the pulley out with higher RPM and the other that will bring the pulley in with higher RPM.
    Connect that to a drive belt. The front pulley will be the one that spreads out with RPM increase and the back pulley will go in with RPM increase. Then connect the equal tooth sprockets either on the same side or as a jackshaft.
    Do you follow me here? This would be essentially be an automatic transmission with smooth variable gearing. Riding it would be smooth and you wouldn't even feel it shifting.
    When the pulley spreads out the belt goes smaller and at the same time when the back pulley goes in the belt get's bigger. Belt tension would essentially be the same thruout and when your stopped,your already set to the low gear.
    In my mind this arrangement shoudn't even have to be big at all. Maybe 3 or 4 inch diameter pulleys should do the trick.
    You can get the springs and centrifical weights from a centrifical clutch or something.
    At least in theory it sounds to me like a winner.
     
  17. Douglas65

    Douglas65 Guest

    Sounds alot like a CVT. Is that what you are describing? It seems like if you went with the engine/cvt units that are available it would solve a lot of issues as it would gear down engine speed and give gear changing automatically too. The only problem is it's size and especially the width. I don't think you could fit it between your ankles no matter how wide the cranks. Am I wrong?
     
  18. Torques

    Torques Guest


    I am interested in your statement, can you explain in more detail? I am interested in a Gebe system on that hub. Is there a problem with sustained 20 mph speeds?
     
    Last edited by a moderator: Dec 4, 2007
  19. azbill

    azbill Active Member

    there should be no problem with running a kit
    it just can't take it if driven by engine (pedal side)which is what was asked here
     
  20. Egor

    Egor Guest

    There was a fella that got the drive to the right side of the bike and then fetched the chain on to the cluster with a derailleur, gave him 5 speeds. I was wondering if that held up? It was not a happy time engine, was the Honda clone wacker engine 2 hp, with no pedals. I think there was a link for a Youtube video of it. The C V T dive is a good one, but large and in the way. Have fun, Dave
     
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