NuVinci Hub

[member548]

GM developed a CVT in the 50s like that, but materials at the time couldn't effectively transmit engine power. The clamping forces needed to transfer the power of a V8 with out excessive slipping was pretty much crushing the spheres.

[Flo4u2u]

any where you touch the ball its going to be same surface!!!!

[zawzero]

@Flo4u2u You obviously missed the whole concept. Badly.

[cannissolis]

Dude get the big and small radius the right way round.

[saswsz]

are thera any way to use it in the midime size generator ?!!

i shud try thate mybe i can save my gas mony by that cvt transmission :) 

[bartdereu]

watched it a hundred times, i still don't get it !

[mr1000rx]

@bartdereu ditto

[obaidCarkey]

I have watches hundreds of simulations, none of them so clearly as how this guy explains it!

But it doesn't look so maintenance-free as many people say it is!

[fixedgearforlife]

This is so over-engineered. If it ain't broke don't fix it.

[burninmunkeys]

@fixedgearforlife And you're exactly what's wrong with the world today, everyone like you doesn't want to make things better. Why don't you go back to using crank start cars, if it ain't broke, don't fix it, asshole.

[fixedgearforlife]

@burninmunkeys Make me.......asshole. Takes one to know one. Crank start cars?! How about no more cars for personal use. I just think more people should get off their asses.

[burninmunkeys]

@fixedgearforlife I agree, they should. So get rid of Tv's and computers, and make everyone go outside and work.

[burninmunkeys]

@fixedgearforlife Or at least shut off cable and internet to everyone's houses for like 8 - 10 hours a day and make them go outside and work.

[fixedgearforlife]

@burninmunkeys Hey, it sounds good. Something we can all agree on. Oh and don't forget about every McDonalds restaurant too.

[burninmunkeys]

@fixedgearforlife I hate fast food anyway, makes me sick to think how many people frequent those things and how lazy they are not to just stay home and cook. Even though I work at one, I don't have much choice.

[harleynog]

@burninmunkeys immigrants would only complain and get the goverment to change it back,

fucking immigrants.

[GraveHorizon]

This device is like a double rainbow. What does it mean?

[oisiaa]

Chain drive is the only way to go for a bike. When you are the power source, every little bit of friction counts.

[cartmanrlsusall]

@oisiaa true chaindrive is the most efficient,but the goal is to get rid of the clunky shift mechanisms.and seal the drivetrain.look how long chains on recumbent bikes get,internal gear shaftdrive will make them more practical

[redmilkfloat]

What...?

[currishev]

can anybody tell what weight-power ratio of this transmission and it's efficiency. I guess these characteristics can't be better compare to traditional transmissions.

[saynotohutch]

hmm so 8 spheres? they look steel so 1lb spheres? eek it pretty much is similar to a ball differential on a R/C car.

[colin340]

@saynotohutch not like a ball diff

[carlteason]

No reason to feel threatened or get mean about this. It's just another bike part. The concept is not new, but that doesn't mean this new version of the old concept isn't worth a look. We're all interested in bike transmissions....things change and evolve as we go on. Clearly, you can ride without it, but if somebody finds more pleasure in this, where's the harm?

Personally, I'm not interested. But I find it clever and inspirational. I'm glad it's out there, and I'd like to see it succeed.

[carlteason]

No reason to feel threatened or get mean about this. It's just another bike part. The concept is not new, but that doesn't mean this new version of the old concept isn't worth a look. We're all interested in bike transmissions....things change and evolve as we go on. Clearly, yoiu can ride without it, but if somebody finds more pleasure in this, where's the harm?

Personally, I'm not interested. But I find it clever and inspirational. I'm glad it's out there, and I'd like to see it succeed.

[asdfghjklkjhgfdsa555]

Hahahaha youtube video's all end up with arguements that usually consist of "FY$%# you!" I come on this video which is slightly educational and look at batlins and caroliano's arguement below hahahahaha clasic!!!

[666TECHNO666]

its a very clever design but its not really gonna help you get faster easier

[springhill1958]

I worked with a guy who worked on that hub. He said that with the best milling machines they still could not make the parts precisely enough. I love the concept but is that hub in production now? Is it in use as a general industrial ratio box?

[dandooshnanoosh]

very concise and clear. good job explaining.

[bikeskills]

Sure is an appealing idea... no rear derailleur... How about some videos on how to ride? We have some of the top mountain bikers demonstrating the basics at the Bikeskills Channel on YouTube. And, we giving away FREE gear! Subscribe now and enter to win.

[bishopdante]

those balls look a touch on the heavy side but CVT rocks

[sirrisreview]

isn't this the same thing as a vintage hub except with more gears

[projectchon]

this drivetrain combo's efficiency is possibly lower then a $150 department store bike. high internal friction, and weight......

[MrCovertcat]

Some world class riders might disagree with you. Search YT for "Nuvinci experts" and watch the first video that pops up.

[projectchon]

have you test rode one? I had.

[MrCovertcat]

I have a few hundred miles on one as a matter of fact. Did you watch the video I suggested?

[projectchon]

I haven't ride it for hundreds of miles and, I watched the video. As RCWorks from the comment below, My opinion is that the efficiency of the CVT drivetrain is still lower then a tradition set up. Until we see some test and numbers, my view is that the mechanical efficiency of this CVT drivetrain is lower then a tourney grouppo. the idea of CVT is not new, last time I recall... CVT has been around for around 100 years or so, maybe CVT is the answer, but as in now. I just don't see it.

[batlin]

According to Wikipedia, Leonardo da Vinci (perhaps inspiring the name of this device) designed a CVT in 1490!

I haven't tried this one, but there is a belt CVT in my car which seems pretty good. With modern ones, I don't think the efficiency is really a problem. Actually I'm not sure why they're not more popular in cars anyway.

But I've spoken to a couple of guys who use a NuVinci - they like it except for the weight. Hopefully that will improve.

[RCWorks]

How much loss of power is there in this thing? IE how does it stack up against say a set of Dura-Ace hubs and a cassette on power and coast?

If it can match it on efficiency and reliability and weight... then you have a winner

[alienfromirth]

Any ideas as to the gear ratio range that can be achieved with this system versus, say, a typical derailleur system on a mountain bike? I realize it is already in practical use on a bicycle already, but just curious as to the specifics.

[bigshnitzeljesse]

what about using ceramic bearings?

[neocuo]

Beautiful mechanism. But, what about the efficiency? Most chan+sprocket driver train have over 95% efficiency. If this hub has comparable efficiency, it would be wonderful.

[500group]

there is a ton of friction with this system nicely engineered but a horrible principle for human power

[jmac530]

this is a similar concept as a skateboard bearing with the exception of the shifting and it being chain driven. this is just a working, open model without the lubricant for the bearings, so i don't think there would be that much friction.

[tropeolum]

If you have a motor, OK. But if you are the motor, forget it.

Relative high loses (not disclaimed on the site), heavy (3.85-3.95 kg!).

[ad93022]

haha thats half the weight of my bike...nice and practical there (Y)

[shell3504]

so good

[iRidr]

Sounds dodgy

[getoffmyinternet]

Seriously.

[Neonuron]

Looks wonderful. But I wonder how long this kind of constant velocity system lasts without slippage.

[batlin]

It's "continuously variable", not "constant velocity".

Surely if you set it to its maximum ratio and stamp on the pedals going up a hill, it will quickly slip (like my bike with worn gears and stretched chain does, but with only a small amount of pedal force :/). This might protect the mechanism from wear somewhat.

I'd like to see how this fares after continuous, rigorous usage - will the lubricating fluid transfer away heat from friction during slippage and mitigate mechanical wear?

[Caroliano]

Based on what you are saying that it would quickly slip in those conditions? I hate when people take affirmations out of their asses and say it like it was truth. ¬¬

I could not find any report on slipage, under much worse use than you described. Please disclose your readings/experiences in it.

[batlin]

I hate when people assume (out of their asses) that other people are taking affirmations out of their asses :P

The NuVinci is a toroidal traction CVT, which uses dynamic friction to transfer force (like most CVT designs). My point was that putting excessive, sudden load on the CVT will cause it to slip, which is probably a good thing (if the choices are either slip or be damaged).

Check out the CVT article on Wikipedia (ratcheting and toroidal in particular) and don't be so rude next time.

[Caroliano]

What you said before is still false, and that is what I critized. The torques that may cause it to slip are greater than the ones encountered by normal use, contrary to what you said.

And I'm not even sure if it will slip, as it varies the compression based on input torque, so to minimize energy loss with lower torques. Then the question is: will it slip or will it break when too much torque is applied? I don't know, but I also would guess slip.

[batlin]

The amount of force required to make it slip was indeed speculation on my part, which is why I said "surely". If I said it "like it was truth" as you unfairly asserted, I wouldn't have added that qualifier.

You shouldn't insult people or jump down their throats when they make logically reasonable speculation. Just adding or contradicting with your own knowledge is sufficient.

I'm unsure as to the slip/break question - someone said that the fluid layer pushes friction up when it solidifies.

[Caroliano]

I'm not a native english speaker, so it may be an misunderstand in my part, but cheking the dictionary, I see:

surely: certainly, for certain, for sure, sure, sure as shooting, sure enough

Wich in my undesrtand is that you don't have any doubt about it, and should not be used if you are speculating.

[batlin]

Then allow me to broaden your understanding of that word in the context in which it was meant.

From Random House online dictionary:

3: (in emphatic utterances that are not necessarily sustained by fact) assuredly: "Surely you are mistaken."

And from Cambridge online:

"used to express that you are certain or /almost certain/ about something"

[Caroliano]

Oh, sorry for the misunderstanding. I myself would use "probably", "I guess", "I think" an things like that. And sorry for the uncalled rudeness.

[batlin]

NP, it's always good to critically examine our assumptions and theories anyway.

[thazit]

very helpfull

[theinsane101]

there is another transmission that uses two steel rings and a steel belt.

[getoffmyinternet]

Wow. Specific.

[Laofse]

Isn't that just a reinforced version of the belt-driven CVT?

[baroen]

Originally a "variomatic" invented by DAF in the Netherlands.

[madcad77]

This method of cvt relies on friction to transfer power to the wheel, without it the mechanism would slip. This means that not all of the effort imputed by the used gets through to actully drive the wheels. Excesive friction is the underlieing problem with all CVT systems, and in my opinion it is the reason none have been successful.

[47f0]

Due to the phase change fluid being used, internal friction losses are very comparable to any planetary-geared hub - think Nexus, for example. Or most car transmissions.

[batlin]

I don't think that's true. If you're talking about the torque convertors used in automatic car transmissions, that's because fluid is used to transmit the power from driveshaft to wheels.

In this case, fluid only seems to be used as a lubricant - the power is transmitted through friction with a sphere (which is quite an aerodynamic shape, anyway).

According to another video on this CVT, the fluid solidifies briefly at contact points due to pressure - like a lockup clutch. Which is good!

[47f0]

Nope - I was referring to efficiencies of planetary-gear transmissions - or manual car transmissions which use conventional gearing. I think this hub should be at least as efficient as them.

As you noted, the fluid solidifies under pressure, which is why I called it a phase-change fluid.

[leeson86]

The fluid is not there to be a lubricant.

[MrCovertcat]

I think the fluid is there both as a lubricant (this thing has to have bearings in it somewhere) and to transfer torque, like it says in the other video.

[theinsekt]

cool

[MAHODAYI]

hmmm awesome