Is the Nexus 3 speed hub strong enough?

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...
 
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.
 
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.
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.... :D

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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"...)
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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).

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


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?
 
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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?

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
 
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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