Utility Cycling - NuVinci Human-Powered Transmission

Has anyone heard of this transmission for bicycles? Continously Variable Planetary, does this sound like something that is revolutionary. Any "engineers" in the commuting forum?

The Nuvinci Website (http://www.fallbrooktech.com/NuVinci.asp):

The NuVinci transmission uses a set of rotating and tilting balls positioned between the input and output components of a transmission that tilt to vary the speed of the transmission. Tilting the balls changes their contact diameters and varies the speed ratio. As a result, the NuVinci CVP offers seamless and continuous transition to any ratio within its range, thus maximizing overall powertrain efficiency, with no jarring or shocks from the shifting process, and improving acceleration, performance and overall vehicle efficiency over conventional transmissions.

Here an animated demo. (http://www.fallbrooktech.com/02_Demo.asp#)

FAQ about bicycle use. (http://www.fallbrooktech.com/06_Bike_FAQ.asp)

Data Sheet. (http://www.fallbrooktech.com/ATC_Bike_Datasheet_090706.pdf)

http://www.fallbrooktech.com/images/hub_breakout_th_500px.jpg

Sheldon Brown website:

http://www.sheldonbrown.com/gloss_i-k.html

The most widely known form of internal gearing is the three-speed utility bicycle. 4-and 5-speed hubs have also been available for many years, but went out of fashion during the early '70's bike boom. Shimano, Sram (formerly Sachs) and Sturmey-Archer have started marketing 7- and 8-speed hubs. Sram offers a 9-speed model, and Rohloff offers a 14 speed model. Fallbrook Technology's NuVinci hub is continuously variable, essentially offering an infinite number of "gears."

Not seen that before. Looks intriguing.
Here are two of the bikes that uses it.
$3k for the Al frame, $4k for the carbon.
I'd guess the hub is around $1k

http://homepage.mac.com/awcg/.Pictures/Bike/TheRide.gif (http://www.ellsworthride.com/)

Ellsworth eh... sounds like they're aligning themselves about as far away from the "practical" and "value" market as possible.

No number for efficiency given there. The losses are likely to be associated with solidifying of the fluid and possibly any slipping in the area where the fluid is squeezed, particularly given rotational mismatch there.

Its gear range is 350% though so ya its great you can fine tune to any "gearing" you want but you're confined within a certain relatively narrow range. The Shimano 8 speed internals are 307% for reference and then 14 speed Rohloff is somewhere in the 500s

I find the idea cool but I have no personal qualms with how the current internally hub gears work. A 13% gear change is fine by me.

in order to get enough friction that the power would be transmitted without the balls slipping, the mechanism would have to be very accurately built, especially the seals for the "special fluiid" and probably be quite inefficient. it does not compare efficiency anywhere on the site.

continuous gear would be great if it could be as efficient as a normal drive train and not complex/expensive/heavy

CVTs have a reputation for inefficiency and for slippage. That's not a big problem in industrial equipment (I don't care of my 3hp Bridgeport milling machine motor delivers 2.8hp to the spindle due to losses in the cone-pulley CVT, after all) but it's obviously a big deal in a bicycle. With the balls, rings, and fluid, I also have to wonder how heavy it is.

It's a neat device, and if it really works as well as they imply it could be pretty cool. I'll wait until I see hard numbers for efficiency before I get too excited about it, though; the trade magazines are full of innovative, breakthrough mechanical products that somehow seem to consistently fail to live up to their advertising hype.

Here's an early (positive) review of the NuVinci transmission thingy in use. It's heavy, a whopping 4,2kgs.

http://phil.veloblog.ch/post/7/333

--J

Bicycle at the 2007 Handmade Bike show with the Nuvinci Hub.

http://gallery.mtbr.com/data/mtbr/981/DSC4188.JPG

Bicycle at the 2007 Handmade Bike show with the Nuvinci Hub.

Pic. (http://gallery.mtbr.com/showphoto.php/photo/72845/size/big/cat/981)

Huh--I didn't believe the 4 kg weight until seeing that bike--wow!:eek:

Wow, I just read about this recently. For those wondering about the efficiency of the drive, the review that Juha pointed to lists the manufacturer's claimed efficiency at 97% and concluded that it's probably accurate.

4.2 kg is some serious weight though. :eek:

If they made it automatic then I'd buy it.

Given the light weight and high efficiency of a standard roller chain drive and the huge ratio count now available (up to 3x10, with perhaps 25 or 26 usable gears), I see no benefit whatsoever to a CVT for bikes. Give me a 5 or 6 percent ratiometric progression from the low 40s to the mid 90s (gear-inches), and I have everything I need. (In fact, I already have it!) CVT for bicycles is a solution in search of a problem.

Even though every car I have owned has had an automatic transmission (I haven't even driven a stick in almost 25 years), the concept of an automatic transmission for bicycles is completely unattractive to me. I want to know when it going to shift, I don't want to be caught by surprise, and I want to be able to vary my cadence as desired.

The only new bicycle transmission technology which intrigues me is the manually controlled electromechanical derailleur set, which I think both Shimano and Campagnolo, and perhaps SRAM as well, have prototyped. The benefits would be automatic trimming of the front cage and multiple locations for gear controls, such as on the drops and on the brake hoods.

Given the light weight and high efficiency of a standard roller chain drive and the huge ratio count now available (up to 3x10, with perhaps 25 or 26 usable gears), I see no benefit whatsoever to a CVT for bikes. Give me a 5 or 6 percent ratiometric progression from the low 40s to the mid 90s (gear-inches), and I have everything I need. (In fact, I already have it!) CVT for bicycles is a solution in search of a problem.

Even though every car I have owned has had an automatic transmission (I haven't even driven a stick in almost 25 years), the concept of an automatic transmission for bicycles is completely unattractive to me. I want to know when it going to shift, I don't want to be caught by surprise, and I want to be able to vary my cadence as desired.

The only new bicycle transmission technology which intrigues me is the manually controlled electromechanical derailleur set, which I think both Shimano and Campagnolo, and perhaps SRAM as well, have prototyped. The benefits would be automatic trimming of the front cage and multiple locations for gear controls, such as on the drops and on the brake hoods.

+1, except, we should probably recognize that this project's purpose is just to explore technology, not to reach the mass market.

+1, except, we should probably recognize that this project's purpose is just to explore technology, not to reach the mass market.

Have you heard this from the designer?

Seems contrary to most successful business models.

Have you heard this from the designer?

Seems contrary to most successful business models.

You're right, I don't know this first hand. The reason I wrote that is that from a price and weight (and function) standpoint, it categorically can't be intended for any large market, unless you consider super high-end quirky gear to be a large market, which it might be, but it's not mainstream. Very few bikes will have this.

Given the light weight and high efficiency of a standard roller chain drive and the huge ratio count now available (up to 3x10, with perhaps 25 or 26 usable gears), I see no benefit whatsoever to a CVT for bikes. Give me a 5 or 6 percent ratiometric progression from the low 40s to the mid 90s (gear-inches), and I have everything I need. (In fact, I already have it!) CVT for bicycles is a solution in search of a problem.

Even though every car I have owned has had an automatic transmission (I haven't even driven a stick in almost 25 years), the concept of an automatic transmission for bicycles is completely unattractive to me. I want to know when it going to shift, I don't want to be caught by surprise, and I want to be able to vary my cadence as desired.
You're last statement is exactly the reason why I find the CVT attractive. If it's shifting continuously then there are no jumps. Nothing to catch you by surprise. You just keep applying the same effort to the pedals and the bike adjusts its speed accordingly.

And I'm sure an adjustment could be added to change the parameter of the automatic transmission so you could vary your cadence. The important thing is that you'd only have to vary it when you want to change cadence, not because the terrain changed.

That's an amazingly good efficiency. I tend to take manufacturers' ratings with a large grain of salt, but if they're claiming 97% it's got to be pretty decent in any case. If you can get past the weight it's a pretty neat setup.

I'd love so see something like that with an automatic control - rather than the twist grip selecting the drive ratio, let the twist grip control the cadence. If you start spinning too fast it'll lower the ratio to keep your cadence in the target zone, and if you start spinning too slow it'll raise it. If you want to adjust your cadence you just have to twist the grip.

It's probably still not something I'd buy - I love hearing the derailleur snick back and forth when I change gears. :)

"I want to know when it going to shift, I don't want to be caught by surprise, and I want to be able to vary my cadence as desired."

Better re-read their web page. You do control the "pitch".

"You’ll find yourself shifting without thought, whenever you feel like it - while you’re pedaling, when you’re coasting (freewheeling), when you’re pedaling backwards, even when you’re stopped. There’s no hesitation, no noise, no waiting for the mechanism to “hunt” for the gear you’ve selected, nothing to synchronize, nothing to guess at, a simple twist of your wrist and you’re at a new ratio."

If they made it automatic then I'd buy it.

:lol:

Seems like NuVinci is a hit. In bicycle-country no. 1 (The Netherlands) one of the leading bike manufacturers (Batavus (http://www.batavus.nl)) introduced three models with the NuVinci hub. One of these models won the Dutch bike innovation award and is Dutch bike of the year. These bikes sell like hot cakes.

I'm sure next year more manufacturers will follow.

These bikes sell like hot cakes.
I just took a look at the home page you listed in your User Profile. Is there a connection between you and the NuVinci manufacturer?

Is there a connection between you and the NuVinci manufacturer?No, not at all. The only connection is: I own one of these bikes and love it. Sorry the site only is in Dutch.

The site is set up to gather user reviews of the hub with pros but also with cons.

OK, sorry I missed the disclaimer at the bottom of your web site.

--J

Ellsworth eh... sounds like they're aligning themselves about as far away from the "practical" and "value" market as possible.

And that's Ellsworth for you.

That titus is freakin sweet. ANy closer pics of the gear change mechanism on the bars?

Here's a thread of a different bicycle with the Nuvinci hub installed. (http://forums.mtbr.com/showthread.php?t=296281&highlight=nuvinci)

Interesting video. (http://www.youtube.com/watch?v=Smijjy832X0&mode=related&search=)

Heh. I saw almost exactly that same exact cross-sectional drawing of a CVT in a Popular Mechanics magazine back in the 60s.
Of course, that was for city busses. They never caught on back then. CVTs are becoming common on some small cars.
I'd wonder about their efficiency.

So how well would this fluid-based transmission shift at -20*F? Not very damn well, I bet.
There are some automatic transmission bikes around and I don't like them. Not knowing when the bike is going to shift can do bad things to your legs and knees. CVT probably not so much but I'll believe high efficiency and good cold shifting when I see it.

Its gear range is 350%...
That's the range of the new SRAM iMotion 9 hub.

TCS

So how well would this fluid-based transmission shift at -20*F? Not very damn well, I bet.I don't think I would ride a bike at all at subzero temperatures. Staying upright on a surface of snow and ice would be the main problem, not efficiency problems of the transmission. But of course it would be nice to know something about the performance in winterly conditions.


There are some automatic transmission bikes around and I don't like them. Not knowing when the bike is going to shift can do bad things to your legs and knees. CVT probably not so much but I'll believe high efficiency and good cold shifting when I see it.The NuVinci is not an automatic transmission. You do the shifting by hand. Very smooth without any stress to legs and knees at all. A conventional hub gives more stress...

I don't think I would ride a bike at all at subzero temperatures. Staying upright on a surface of snow and ice would be the main problem, not efficiency problems of the transmission. But of course it would be nice to know something about the performance in winterly conditions.

The NuVinci is not an automatic transmission. You do the shifting by hand. Very smooth without any stress to legs and knees at all. A conventional hub gives more stress...

Come on, Fransb! So far, you are the only member with first hand knowledge.

Post some pics of that bike. And give us your honest opinion of the Nuvinci Hub. The good and the bad.

My hub has two gears

I have 3 speeds

Sitting, standing, and panting

I ride an Ellsworth Truth, full suspension mtb which is a very nice bike, but at least similar in price to many high-end mtbs. The Ride, which features the Nuvinci hub, starts at $3k, way beyond the typical cruiser bike, and I don't know of any other "high-end" cruisers to compare to. I agree with JeffS...not practical. Value is a whole other question and up to the buyer. It does look pretty sweet to me!

Come on, Fransb! So far, you are the only member with first hand knowledge.

Post some pics of that bike. And give us your honest opinion of the Nuvinci Hub. The good and the bad.Don't believe me ?:eek: So here are some photos.
My former bike had a derailleur: smooth operation, but completely worn off because of dirt and mud. So I was looking for a bike with (at least) a Shimano Nexus - 8 closed Hub. Then suddenly there was the NuVinci....

My opinion:
+ very smooth operation, even a lot smoother then a derailleur, so no stress to legs and knees (when shifting)
+ solid, I expect no maintenance problems
+ you can always shift, even when stopping for a traffic light (when you forgot to shift down)

- it is heavy, but hardly noticable driving on a bike like this
- you still have to release some force on the pedals before shifting

I was worried about the fact that the full 350% gear range is equivalent to turning the shifter around twice, but in reality you shift only a little bit so this is not a problem at all.

Overall I think the hub is very solid and well designed but the main problem is the weight.

Edit: While reading this thread once again I noticed that some people still think the NuVinci has something to do with an automatic gear. This is not true. It is just a continuous transmission independant of the input force or speed. You keep all the control yourself. Look at it as a Shimano Nexus-infinitive of a Rohloff Speedhub 350/infinitive.
The NuVinci is a completely new design, but when using it it is not at all that different from a conventional hub (though a lot more pleasant).

The NuVinci is a completely new design, but when using it it is not at all that different from a conventional hub (though a lot more pleasant).
Thanks!
does it feel any less efficient than a conventional drivetrain?
I was worried about friction losses and/or slipping

I was worried about friction losses and/or slippingNo friction losses, no slipping.

Has anyone heard of this transmission for bicycles? Continously Variable Planetary, does this sound like something that is revolutionary. Any "engineers" in the commuting forum?

The Nuvinci Website (http://www.fallbrooktech.com/NuVinci.asp):

The NuVinci transmission uses a set of rotating and tilting balls positioned between the input and output components of a transmission that tilt to vary the speed of the transmission. Tilting the balls changes their contact diameters and varies the speed ratio. As a result, the NuVinci CVP offers seamless and continuous transition to any ratio within its range, thus maximizing overall powertrain efficiency, with no jarring or shocks from the shifting process, and improving acceleration, performance and overall vehicle efficiency over conventional transmissions.

Here an animated demo. (http://www.fallbrooktech.com/02_Demo.asp#)

FAQ about bicycle use. (http://www.fallbrooktech.com/06_Bike_FAQ.asp)

Data Sheet. (http://www.fallbrooktech.com/ATC_Bike_Datasheet_090706.pdf)

http://www.fallbrooktech.com/images/hub_breakout_th_500px.jpg

Sheldon Brown website:

http://www.sheldonbrown.com/gloss_i-k.html

The most widely known form of internal gearing is the three-speed utility bicycle. 4-and 5-speed hubs have also been available for many years, but went out of fashion during the early '70's bike boom. Shimano, Sram (formerly Sachs) and Sturmey-Archer have started marketing 7- and 8-speed hubs. Sram offers a 9-speed model, and Rohloff offers a 14 speed model. Fallbrook Technology's NuVinci hub is continuously variable, essentially offering an infinite number of "gears."


Looks a lot like Nissan's CVT design:

http://www.echoscaninc.com/product_images/448-0.jpg

So how well would this fluid-based transmission shift at -20*F? Not very damn well, I bet.
There are some automatic transmission bikes around and I don't like them. Not knowing when the bike is going to shift can do bad things to your legs and knees. CVT probably not so much but I'll believe high efficiency and good cold shifting when I see it.
I don't believe the transmission is fluid based. There have been some hydrostatic transmissions but the NuVinci is all mechanical.
This is not an automatic transmission like the new Coast set from Shimano, rather this is a manually shifted hub gear with a continuously variable transmission. If its easier to grasp, think of it as having hundreds of gears with very small differences in gear ratios.
The claims are for high efficiency and apparently they are atleast in the same range and a hub gear. I'll have to wait to seem some independent tests or first hand experience before I make judgment there. There should not be any problem with cold shifting, though it is possible that efficiency may suffer more a colder temps.

Craig

I don't believe the transmission is fluid based. There have been some hydrostatic transmissions but the NuVinci is all mechanical.Not true. NuVinci uses Valvoline INVARITORC™ Traction Fluid (http://www.fallbrooktech.com/06_tf_FAQ.asp) to transfer the forces.

This looks like a realy neat design. I saw something similar about a decade ago in an Automobile magazine for a unit that was being developed for the automotive and light bus world. There must have been too many problems with that much power transfer. Any of the CVT transmissions have the advantage of very high efficiency compared to a torque converter based transmission. This is most of the CVT cars can match or in somecases exceed the efficiency of a standard transmission.

It also makes sense that this product should come out of The Netherlands. The interal gear hubs are still very popular there for a few reasons. #1 Bikes are a major method of transportation. When I grew up in the Netherlands back in the 70's, we did not get our first car till I was 7 years old. You could do everything on a bike. #2 The weather tends to be wet frequently and the internal gears are nicely protected from the weather and take almost no maintenance. The chains tends to be completely encased in a cover so it also take almost no maintenance. You still see plenty of bikes with 3 speed hubs, and now the higher number gears are become the norm for the higher end bikes. The Dutch bikes are not light weight as they are built for stenght and endurance. My mom would have me on the front handle bars in a bike seat, and my sister on the back bike seat, and a bag of groceries on each handlebar end. Try that with most of the bikes sold in the USA, day in day out, rain or shine, up and down curbs... I don't think most would hold up too well to those kinds of stresses. That is the market this gearing system is designed for. As a side note that Raleigh 3 speed from the 1960's that carried my sister and I when we ere little is still in perfect working order, and the only maintenance that it has needed in 30 years is new tires.

Happy Riding,
André

I don't think I would ride a bike at all at subzero temperatures. Staying upright on a surface of snow and ice would be the main problem, not efficiency problems of the transmission. But of course it would be nice to know something about the performance in winterly conditions.
I ride all winter without problems. Temps are around 10*F (-12*C) typically in the morning, but down to -25*F (-32*C) for about a week last winter. Studded tires solve the staying upright problem; I ride on ice for months at a time and have only fallen once, in my driveway.

I am comfortable riding my bike in conditions that I would NOT be comfortable driving a car in.

If this doesn't work well in temperatures WELL below freezing it's going to not do too well for many commuters that hang out around here.


The NuVinci is not an automatic transmission. You do the shifting by hand. Very smooth without any stress to legs and knees at all. A conventional hub gives more stress...

The reference to automatic transmissions was about a side conversation, not directly about this particular transmission.

It also makes sense that this product should come out of The Netherlands.Helaas komt dit ontwerp niet uit Nederland maar is "gewoon" een Amerikaanse uitvinding. ;)

(transl: The product is not Dutch, but American).

Indeed Dutch bikes are made for endurance. No need for extreme gear ranges because Holland is quite flat. The average bike weighs about 21 kg so the heavy NuVinci is not the greatest portion. So it makes sense that NuVinci is a hit in Holland.

I've tried one. I liked it.

We had one at the bike shop I briefly worked at and I took it for a spin. The first thing you notice is that there's no clicking or ratcheting whatsoever, which at first feels like there's something wrong.

It's nice to be able to shift while you're bearing down on the pedals, and you can constantly be shifting up and down as you ride, instead of leaving it in one "gear". Sounds weird, but I found it natural to ride that way. You don't need to be pedaling to shift, either, which is also cool. Come to a stop and downshift while you're waiting, doesn't matter.

They weigh around 9 pounds, which is heavy for a hub, but I don't know, it eliminates the derrailleur and cassette and all. The grip-shifter contraption has a window built in with a goofy "user-friendly" diagram to show you how to use a bike. Overall, pretty worthwhile. I'd like to own one.

I'd ride one if it a) cost less and b)weighed less...something closer to maybe 5lbs.

Don't believe me ?:eek: .

I believed you.

Thanks for the pics and the info. :beer:

I bought a NuVinci hub built into a wheel for just over $500. I put it on my Giant Lite electric bike.

The Giant Lite is a fairly unique design for an electric because the motor drives through the drivechain in parallel to your own pedalling input. The controller on the motor decides how much to contribute based on your cadence and the load it senses on the drivechain. There is no throttle for the motor.

The ability to tweak the gearing ratio of the NuVinci as I ride makes the electric bike even more fun. I'm able to control gearing enough that I can add in or take out the motor's contribution as I need it. With a fast cadence I can ride over the gearing and the motor reduces its contribution to zero. On hills or into a wind, I can find the exact gearing that will optimize the motor's contribution.

My battery range has improved. I haven't done a scientific measurement, but I think I'm now able to extend my useful riding range from 20 to almost 30 miles. I'm now riding 13-15 miles per day and using less than half the charge on the battery.

I've been riding this setup ever day for six weeks now - 300 miles or so. So far, no problems to report. The motor adds between 240-370 Watts to my own efforts, but there has been no slippage or noises yet.

The extra weight is less of an issue since I'm already riding a 50 lb bike and carrying all my commuting gear and work stuff. What's another 10 pounds (except when the battery dies :-) )

The initial usage experience has been very good, but it's taken a few weeks for me to truly understand how to optimize the increased gearing ratio control to both extend battery life and get maximum assistance when needed.

Krow, where did you get your hub?

The 4+Kg weight does not seem so bad considering you are eliminating two front chainrings, their support works, the front derailluer, One set of shift cables, and all but one of the rear cogs. Could someone tell me how much all of that would weight.

Ken,
The weight comparison article I found on the Rohloff site says that it would be around 1600g or about 3.5 pounds. Source (http://www.rohloff.de/en/info/faq/faq_detail/article/520/284/index.html)