This is the first major change in CVT technology since Salsbury invented the CVT in 1937. Using the Viscous Coupling concept along with the drive variations is really smart. I'm looking forward to seeing how it works out in real life applications.
I just test rode a Novara bike at REI with this transmission. I'm extremely impressed. No clicks, no nothing. Also, you don't have to pedal to change ratios, just a smooth twist. Front sprocket to the rear is by belt. Also very smooth! This transmission might be great for scooters and small motorcycles. We'll see what happens.
Shane SRAM My comment was 100% about the transmission. The only part about REI was that they were cool enough to let me test it. You must be a special kind of stupid.
It's a Knopp variator. (Google it) It's a very old design. As for the fluid, well it's oil. Common or garden oil. All that has been described in the video is the behaviour of any hydrocarbon oil between a ball bearing and the surface it rolls on. It's a neat bit of engineering to get it small enough for a bicycle, but as with the Knopp, efficiency will be low.
Currently CVT transmissions are the MOST fuel efficient transmissions made for over the road vehicles. It allows the vehicle to select the best drive ratio for a given circumstance. This transmissions along with lock up torque converters are much more efficient than both manual trans and traditional automatics. CVT transmissions are standard on most new Nissan, Saturn, and most of the hybrid vehicles on the road and probably many more.
Absolutely brilliant. The manual control because everyone's a different engine of course... but the principle.. Genius!!!! I've often thought of the idea of non-automatic cvt, but most methods until now have been vee-belt based which intrinsically has large frictional losses. Once again... genius!!!
what does it weigh? is it comparable to a mtb hub, cassette, front and rear mech? assuming it'll be run as a single speed chain setup or better yet belt.
@FranktheBBB ye I see a BIG problem with this, although i have not used this, I would image it has a fair amount of slipping going on, meaning torque transfer is dramatically reduced, which is not good enough for pedaling up hills or using low gears. Is this what you experienced? I wonder how they will attack this problem,
@meandmyevo there is larger versions of this device that will handle larger power input.. not sure how big they get but something in the range of 5 hp is already available..
@GRAHAMAUS So... of all the hundreds of Subaru's I've torn into, I have never seen a solidifying traction fluid, nor have I seen a fluid that responds to magnetism in any way. What LSDs on which Subaru vehicles are you talking about?
Not even considering the slippage issue, what's the range on this thing from low to high? From the demo it appears that the range would very limited and if that's the case why would I want this on my bike...unless I live where there is nothing but flat land all arould and in that case I would need only one gear anyway.
@minorlogic Maybe, but I expect the losses may be higher than gears so more pedaling energy turned to heat, I would like to know the efficiency, gears run about 98%+ efficient
@GLOCKIOMM there is actually plenty of energy loss in a chain and sprocket system, with all the hundreds of tiny "bearings" between the links, and the bearings that the axles have to ride on, this design by itself will definitely increase efficiency in almost any system it is properly applied to.
I love this gadget! I think it would be worthwhile--to ease the understanding of this video--to highlight the circumferences of the sphere each disc is in contact with in real time
Hey can someone tell me if it's bad to get this a little submerged in water? I have this on a trike I just got an gotten some water. I was wondering if it's bad. Can someone please reply?
What is the efficiency of this? I want to know for every 100 watts of input power, what is the output power? 85 watts? 90 watts...? Also if they can get a 2:1 ratio on the underdrive side, then why not a 2:1 also on the overdrive side, thus creating a NuVinci 400 (not 360 or 380)? That 4:1 spread of gear ratios might even need 2 front chainrings to select the range needed (high or low) since 0.5 - 2.0 doesn't cover all circumstances. I would want something like 0.5 - 4.0. Also this thing is expensive and doesn't fit all bikes so there are many problems it seems with it. My entire WalMart mountain bike was only about $100 out the door and it has 21 speeds and a gear range (spread) of 3.5:1 which almost matches that of the NuVinci 360 which is 3.6:1. Not sure why this hub cost many hundreds of dollars when I could buy several new bikes for that amount.
@whoseline4gp Hi, CVT stands for continuously variable transmission not automatic transmission, you can have automatic CVT but it is not inherent in CVT design, hope that helps?
This is an interesting system but I have a few questions: What is the weight of the hub? What shaft ratios are available (min and max)? Its surely not infinitely variable as that would suggest any ratio is available, it is continuously variable, meaning there are no discrete ratios between min and max? What is the diam of the hub? I'd be weilling to give this a try if it came in reasonably priced and wasnt much more than the weight of a comparable cassette/mech combination.
@MrMeanderthal That is a very good point. Apparently I wasn't really thinking much when I posted that. I was actually considering this for small-engine applications (chainsaws, go-karts, scooters, etc)
@500group: boy, am I glad I didn't know this thing couldn't work before I went out for an hour long ride today on my spanking new Crescent Nuvinci. I'm no expert, but there was not the slightest sign of the extra friction you guys claim. No slipping. I never noticed the weight either (but now you said it's so heavy, I'll think about it all the time). For all others, rest assured, it works. The "high friction" if it's there at all, is much too small to be noticed even by my lazy legs.
@SamuraiClinton The fastest human powered vehicle goes over 80mph, it was driven by Sam Whittingham. Combination of recumbent bike, streamlined fairing, and LEGS OF STEEL, all made it possible.
We might be interested in investing. How efficient is this transmission on AVERAGE? I am not asking peak eff. Average HP in (X) to HP out (Y) . Y/X = ? eff
wits2014 I've heard anywhere from 70 to 95 percent, which is wildly variable. I think it breaks down as towards the extreme low and high ranges the efficiency drops, and increases towards 1:1.
This is actually a terrific idea! However, this should definately be used in vehicles, whose automatic transmissions suffer from significant losses in friction. Meanwhile, bicycle chains are VERY efficient, will rule all high-performance bicycles for decades to come.
The Cadillac Fleetwood Cruiser bicycles with the NuVinci Shifter are going for FIVE Hundred Dollars and some change, these days. Check it out, its definitely a sweet looking bicycle.
He said CVP at the end i think (2:48) - Am i missing something? And also, I imagine this would let the pedel move if you were resting your weight on it while waiting to go at the lights - unless it has some kind of centrpetal-force-activated gear lock for when your not moving Also, I would prefer a CVT that automatically increased its gear ratio with increased centrifugal force - which I think was the original design goal of CVTs (Am i wrong?) +Compensation for your prefered cadence
@dragonamt The contact fluids used in here are already EXTREMELY difficult to formulate. I cannot imagine(if it's even possible) how complicated and temperamental a fluid with both of those characteristics would be to produce...
Do correct me if I am doing something wrong, but when I Googled Knopp variator I was redirected to this page. Is there a good link where I can read about Knopp variator?
great idea..perhaps a rf fuzzy-logic artificial intelligence device that is continuously communicating with the peddler's 'heart-rate' sensor to monitor variable cadence or level of exertion.
Good god people it's a freakin proof of concept. It's not gonna be on bikes next year. They're just demonstrating it is possible. Give it time and maybe soon enough it'll be smaller, lighter and usable mass market.
it might be good for cars or small engine vehicles like scooters. but i think ur right it will not be good for bikes as there will be some slipping likely and powerloss.
Scalable because you they can add more bearings for different applications. As for how to use it as shown on a bike you would control the ratio with a knob on the handle bar. This method may also work for cheap motorcycles or scooters but in higher class bikes and cars I would assume it would be controlled by a ecu based on throttle position and fuel economy just like the cvt's in cars now.
The shifting of the ball acts like the different size gears... dunno why you don't get the rest, it's simple to me. I just see alot of issues with leaking, and weight. but then I guess the balls could be hollow. although I see the application on heavier vehicles, it seems like alot of device to replace the simplicity of the common gear system on bikes. but I guess its a novelty some might just have to have...
Scheme of the differential variator. 1. Input power is divided into 2 flow through a differential. 2. Flows give a different ratio (up/down) 3. Combine two power flow through the second differential. Remembering that the planetary gear reducer and at the same time differential, we can build the CVT only with two planetary gears. It seems, and the range and efficiency and capacity of the variator at much higher used in automobiles.
@foxtrotHQ Like the "silly-putty" I remember from the science museum.. Pliable like putty if kneaded slowly, but would shatter with sudden impact, then return to being pliable.
nice idea, the basic design is simple in mechanical terms, but unless the internal parts are made from very strudy components, it would wear out very quickly!
well you also lose a lot from the chain shifter - but its more about the gain you get with the 4kg: continously varying "gears" and most importantly no maintenance! i am actually also very much interested in the use for electric bicycles and motocycles and there 4kg is certainly not much.
Some mopeds have a 1 speed transmission, some have a 2 speed transmission, and some have a CVT. Motobecanes, (most) Vespas, Peugeots, and Hondas have CVTs.
I understand the point of CVT. Instead of a set number of gears it's unlimited. But shouldn't it automatically shift by itself? Like the CVT in a moped does.
Is this unit sealed, or what will happen in a wet environment? I want to use your transmission for a super high mileage amphibious vehicle I'm working on for college, but contrary to what your video claims that "this promises to be the most practical and ECONOMICAL cvt", I can't afford one. It costs more than any other component in my plan, and I'm just a student who already can't make ends meet with todays economy. Contact me if you can spare a second hand unit or demo or blem or ?
@cannissolis You can find all required info in mech-ingDOTcom/journal/Archive/2011/2/129_Konstantin%20Ivanov.pdf wwwDOTmadbassDOTnarod.ru./ The efficiency is close to efficiency of Bearing on high speed, because all gears is connected.
@MrMeanderthal the design doesn't really limit power, just torque. if you had an engine that produced 15lb-ft of torque at 30,000+ rpm, that some seriously usable power that almost any tiny tranny could handle.
I'd like to ask, how is the smoothness and adjustability to your desired torque/speed? Do you feel you could pedal up a decent hill? Does it take the cargo strain off you? Any input would be helpful, thank you.
@@justinwhite1928 it is very smooth and it is nice because you can adjust on the fly without worrying about snagging your gears. In addition to the NuVinci, I use a Bafang middrive motor for additional power, since the bike is quite heavy and I live up a steep hill. I've meant to make a video about the setup, so maybe I will now. I have nearly 500 miles with this current setup.
Terrible, but Nuvinci will never publish official ratings, and they'll speak out heavily against 3rd party testing. I've even seen their PR team going through the various forums and trying to end any discussion on their efficiency rating. If they have to be so secretive about it, then clearly they're guilt ridden with poor performance.
Not a novelty, for bikes, but the problem is weight. See to ride a bike at maximum efficiency you should ideally pedal at a set speed and decrease or increase your moving speed by changing gear. EG spin your pedals at 1.5 times per second and change gear to change bike speed. This is the most efficient way to ride a bike and racing cyclists would love it. The downside is that if the thing weighs 4 kg it is too heavy for a bicycle.
Special spokes??? It's just a hub - it has spoke holes - lace it and ride. As far as ratios go, the first production units have a range of 350%, which is wider than you think. The efficiency, due to the special transmission fluid is excellent. Of your objections, only the weight, (around 10 lbs) even counts, and given the ability to easily have low-maintenance shifting, I can sacrifice a little weight - contrast that to, say a Nexus hub, at about 3.4 lbs, and the weight difference is even less.
+mike nixon Even regular sprockets have limited ratios, and this could actually have better range of ratios, but the problem is that there might be some power loss. Chain drive has nearly 0% power loss. This is dependent on friction, so it's likely that you will lose some power.
idk about these things, still sounds like they could use some work. I think I'll stick to my 21-speed twist shift for now lol but that new KERT flywheel motor sounds very promising lol.
