NuVinci Human-Powered Transmission
#1
Retro-nerd
Thread Starter
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:
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.
FAQ about bicycle use.
Data Sheet.
Sheldon Brown website:
https://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."
The Nuvinci Website:
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.
FAQ about bicycle use.
Data Sheet.
Sheldon Brown website:
https://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."
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Last edited by georgiaboy; 03-27-07 at 04:59 PM.
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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.
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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.
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.
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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
continuous gear would be great if it could be as efficient as a normal drive train and not complex/expensive/heavy
Last edited by neutron7; 03-27-07 at 10:34 PM.
#7
Goathead Magnet
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.
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.
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Here's an early (positive) review of the NuVinci transmission thingy in use. It's heavy, a whopping 4,2kgs.
https://phil.veloblog.ch/post/7/333
--J
https://phil.veloblog.ch/post/7/333
--J
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#9
Retro-nerd
Thread Starter
Bicycle at the 2007 Handmade Bike show with the Nuvinci Hub.
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Last edited by georgiaboy; 03-30-07 at 06:22 AM.
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Originally Posted by georgiaboy
#11
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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.
4.2 kg is some serious weight though.
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#13
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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.
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.
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Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
Last edited by John E; 03-30-07 at 08:33 AM.
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Originally Posted by John E
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.
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.
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Originally Posted by NeezyDeezy
+1, except, we should probably recognize that this project's purpose is just to explore technology, not to reach the mass market.
Seems contrary to most successful business models.
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Originally Posted by JeffS
Have you heard this from the designer?
Seems contrary to most successful business models.
Seems contrary to most successful business models.
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Originally Posted by John E
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.
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.
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.
#18
Goathead Magnet
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'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.
#19
Really Old Senior Member
"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."
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."
#21
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NuVinci is going to stay
Seems like NuVinci is a hit. In bicycle-country no. 1 (The Netherlands) one of the leading bike manufacturers (Batavus) 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.
I'm sure next year more manufacturers will follow.
Last edited by fransb; 05-30-07 at 02:29 AM.
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Originally Posted by fransb
These bikes sell like hot cakes.
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#23
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Originally Posted by Juha
Is there a connection between you and the NuVinci manufacturer?
The site is set up to gather user reviews of the hub with pros but also with cons.
#24
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OK, sorry I missed the disclaimer at the bottom of your web site.
--J
--J
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#25
No Talent Assclown
Originally Posted by JeffS
Ellsworth eh... sounds like they're aligning themselves about as far away from the "practical" and "value" market as possible.
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