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than the disc (this phenomenon of traction-type CVTs is referred to as "contact spin"). "The spin velocity (or drill speed) is defined as the difference in the rotational speed of the driving and driven rollers in a direction perpendicular to the contact patch plane. It is caused by the relative difference in surface speeds of both elements across the contact patch and is a major source of power loss in traction drive CVT’s." In all traction-type CVTs, this relative sliding necessarily occurs between surfaces which are under the very high clamping pressures required to ensure torques are transmitted reliably. This relative sliding under high pressures cause transmission losses (inefficiency). Fallbrook
Technology refuse to publish any efficiency data for the NuVinci CVT. However, the NuVinci is a variant on the "tilting-ball drive" type of continuously variable transmission (CVT), and the efficiency of "tilting-ball drive" type CVTs is typically in the range of 70% to 89%. However, its geometry does differ significantly from the Kopp type of tilting ball variator in the reference in that the NuVinci has its torque transfer contacts on the outside diameter rather than the inside diameter, which puts the idler (an element that reacts clamping load) in compression rather than tension, and because the idler contact surface is not conformal as in the Kopp design. In general because of the way the CVT is set up, it is more efficient at a 1:1 ratio compared to maximum overdrive or underdrive positions. Independent test results have shown that at 1:1 it is actually more efficient than comparable bicycle internal gear hubs, while at the ratio extremes it is slightly lower.
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model announced early
September 2010 weighs 2.45 kg (5.4 lb). That same article points out that "the combined weight of Shimano SLX front and rear derailleurs, shifters, freehub and cassette comes out to about 1.3 kg (2.9 lb)". However, the NuVinci CVT is targeted towards the less weight-conscious (
386:
As with other traction-type CVTs, transmission of torque through the NuVinci CVT involves some relative sliding between the torque-transmitting contact patches. This is because, for any given contact patch, parts of the ball are going in a slightly different direction and at slightly different speeds
452:
14-speed hub gear or most mountain/hybrid/touring bicycles with triple chainrings. By conventional standards, a NuVinci bicycle hub is considered heavy. The second generation model N171B weighs between 3.85 and 3.95 kilograms (8.5 and 8.7 lb), including freewheel and mounting hardware. The N360
611:
NuVinci has been rebranded to
Enviolo as part of a bankruptcy restructuring. The former model N380 was renamed to TR for trekking. N330 is now the CI variant for city (CO for commercial renting systems is the same, but may offer different color schemes). Stronger models SP (sportive) and CA (cargo)
244:
within its range. The gear ratio is shifted by tilting the axles of the spheres in a continuous fashion, to provide different contact radii, which in turn drive input and output discs. The system has multiple "planets" to transfer torque through multiple fluid patches. The spheres are placed in a
359:
The NuVinci CVT further offers the ability to accept multiple inputs while varying speed and ratio, managing torque and providing single or multiple power outlets. By supporting a torque-demand rather than a speed-demand control solution, the NuVinci CVT solves the low-speed acceleration problem
355:
if such gain in the efficiency or performance of the power plant exceeds any loss in efficiency or performance that may be introduced by replacing the conventional transmission with the NuVinci CVT. For example, if the NuVinci CVT were only 90% as efficient as the conventional transmission it
465:) segments with the latest product introductions the N330 and N380 also being targeted at city, urban, trekking and eMTB (SUV) bikes. Their biggest advantage is the durability, while shifting under load and continuously, which is especially important with the powerful eBike drive systems.
356:
replaced, the gain in operating efficiency from the power plant would have to be 11% (i.e., 1/0.90 - 1 = 0.11 or 11%) before the overall efficiency improved. The company does not provide any numbers relating to efficiency of their transmissions, and has declined to do so when requested.
215:
existed since the 1800s, and have been used successfully in machinery, particularly the Kopp tilting ball variator. Various attempts have been made to implement them in vehicle transmissions, but commercial success has been elusive.
375:
The NuVinci uses rolling traction to transfer torque, just as do toroidal transmissions. However, unlike toroidal CVTs, it distributes the transmitted torque over several spheres, thus lowering total clamping force required.
235:
positioned between the input and output discs of a transmission. Tilting the balls changes their contact diameters and varies the speed ratio. As a result, the NuVinci CVT system offers seamless and continuous
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38:
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with 8- or 9-speed hub gears, or with double chain rings (most racing or fast road bicycles). This range is somewhat less than the 526% range found on bicycles with a
401:
Other advantages shared with similar CVT designs include that the input and output shafts may be either in-line, offset, or in a U configuration (input and output both
76:
715:
223:. In June 2018, the company emerged from restructuring under Chapter 11 bankruptcy, and under new ownership the bike division was rebranded as Enviolo.
390:
Torque inputs can be summed or divided, just as in a conventional planetary. Ratio control is stable, and can be actuated down the center line of the
253:
and compact. The result is the ability to sweep the transmission through the entire ratio range smoothly, while in motion, under load, or stopped.
44:
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814:
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640:, a manufacturer of bicycle frames and wheels designed a bicycle around the Nuvinci CVT. In 2007, The Ellsworth Ride received top honors in
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The 3.6 kg (8 lb) NuVinci rear hub. Comparatively, the newer NuVinci hubs from around 2010 weighs 2.4 kg (5.4 lb)
379:
This arrangement allows the NuVinci CVT to combine the smooth, continuous power transfer of a CVT with the utility of a conventional
347:, human or motorized, to operate at (or closer to) its speed of optimal efficiency, output torque or output power, the NuVinci CVT
220:
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Fallbrook
Technologies, parent company of Enviolo and NuVinci, emerges from bankruptcy | Bicycle Retailer and Industry News
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394:, which again is similar to the proven planetary transmission. In most applications, there is no need for high-pressure
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In 2017 it was announced that NuVinci
Cycling would be renamed as Enviolo. In February 2018, the company filed for
684:
249:(the sun) and contact separate input and output traction discs. This configuration allows input and output to be
95:
748:
436:. The only application currently commercialized is the internally geared bicycle hub. The NuVinci CVT replaces
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1001:
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that, under normal circumstances, provides lubrication for the drive. When this fluid undergoes high contact
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improve a system's overall efficiency or performance compared to a 'conventional' geared transmission, but
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Bicycles equipped with NuVinci transmissions subsequently won iF Design EUROBIKE awards in 2010 and 2011.
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Two factors allow the NuVinci CVT to provide a continuously variable ratio range in a compact package:
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Fallbrook hasn't publicized this metric (and there's been some grumbling from critics about this)
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The system and associated bicycles have been the recipients of several awards. These include:
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The company is also developing products based on the CVT unit for automotive applications.
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8:
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Fallbrook claims the transmission control is stable, linear and does not require a major
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can be transferred. Note that the rolling elements are actually not in physical contact.
145:
Please help update this article to reflect recent events or newly available information.
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268:. Contacting a rotating sphere at two different locations relative to the sphere's
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The NuVinci CVT's simple design and low part count make it easily scalable, with
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the molecules of the fluid stack up and link to form a solid, through which
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configuration of the drive, which is based on differing contact ratio of a
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magazine's annual Best of What's New review of significant new products.
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The NuVinci CVT system has a small number of parts. Most CVTs have lower
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technology currently under development for other applications, including
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NuVinci
Cycling rebadges as Enviolo, becomes independent to Fallbrook
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The NuVinci CVT may be applicable to many different products using a
409:), making the transmission simple, small, light and easy to package.
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depending on the location of the contact points for input and output
1032:. International Forum Design Hannover. July 19, 2011. Archived from
444:, and provides a gear ratio range of about 350%, similar to that on
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Bicycling
Magazine's Editor's Choice for Commuter Bike of the Year
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291:(EHL). Transmissions that use EHL to transfer power are known as
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will provide a “gear ratio”, which can range from underdrive to
1050:. Fallbrook Technologies Inc. September 8, 2018. Archived from
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The NuVinci CVT gear system uses a set of rotating and tilting
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Technology of the Year and Bike of the Year in The
Netherlands
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under rolling contact between the two very hard elements, the
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that can be used across a wide variety of applications.
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and the discs, the fluid undergoes a near-instantaneous
815:"Testing the Novara Gotham: A Bike With Infinite Gears"
870:
295:. A traction drive transmission operates utilizing a
896:. McGraw-Hill. December 11, 2006. pp. 343–344.
94:, and by adding encyclopedic content written from a
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574:330% nominal, 0.5 underdrive to 1.65 overdrive
16:Roller-based continuously variable transmission
894:Mechanisms & Mechanical Devices Sourcebook
848:"The Turbo Trac Traction Drive CVT (04CVT-38)"
599:380% nominal, 0.5 underdrive to 1.9 overdrive
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340:than competitive conventional transmissions.
964:
941:"Fallbrook Technologies Product Information"
836:
812:
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800:Rheology and Elastohydrodynamic Lubrication
682:
370:
53:Learn how and when to remove these messages
523:350% (0.5 Under-Drive to 1.75 Over-Drive)
918:"NuVinci® Range and Gear Inch Comparison"
845:
687:. Eureka, the site for engineering design
360:inherent in some torque-demand vehicles.
168:Learn how and when to remove this message
114:Learn how and when to remove this message
871:Rich Wood and Jornole (9 October 2007).
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500:Weight (excluding auxiliary components)
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332:Comparison to conventional transmissions
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75:contains content that is written like
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630:An iF Design EUROBIKE Gold 2008 Award
549:360% 0.5 underdrive to 1.8 overdrive
201:automotive front-end accessory drives
1116:Automotive transmission technologies
967:"NuVinci Releases N360 Transmission"
526:3.85–3.95 kg (8.5–8.7 lb)
471:
125:
59:
18:
1111:Continuously variable transmissions
943:. Fallbrooktech.com. Archived from
13:
965:Ben Coxworth (September 1, 2010).
659:Continuously variable transmission
605:City, Urban, Trekking, eMTB (SUV)
14:
1137:
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727:Fallbrook – enviolo Has New Owner
34:This article has multiple issues.
245:circular array around a central
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747:Frank Markus (September 2006).
685:"Variators improved with power"
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199:, outdoor power equipment, and
42:or discuss these issues on the
1002:"2011 Editors' Choice Winners"
853:. Southwest Research Institute
806:
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709:
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638:Ellsworth Handcrafted Bicycles
289:elastohydrodynamic lubrication
1:
813:Michael Berk (June 7, 2012).
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434:mechanical power transmission
1066:"The Infinitely Geared Bike"
315:solid. Within this patch of
7:
1126:Products introduced in 2006
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602:2.45 kg (5.4 lb)
577:2.45 kg (5.4 lb)
552:2.45 kg (5.4 lb)
184:Internal CVP shift machine.
10:
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683:Tom Shelley (2003-08-13).
343:Since any CVT may allow a
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139:This article needs to be
371:Comparison to other CVTs
988:"NuVinci N171 and N360"
873:"NuVinci N171 and N360"
654:Comparison of hub gears
612:have been added since.
798:B.O. Jacobson (1991).
442:internally geared hubs
429:
185:
1096:NuVinci Official site
1048:"Awards & Honors"
1030:"EUROBIKE AWARD 2008"
427:
338:mechanical efficiency
287:The second factor is
221:Chapter 11 bankruptcy
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96:neutral point of view
616:Awards and publicity
416:development effort.
779:"NuVinci® Overview"
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88:promotional content
990:. October 9, 2007.
875:. Hubstripping.com
749:"The NuVinci Code"
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90:and inappropriate
1008:. April 13, 2011.
903:978-0-07-146761-2
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472:Bicycle hub gears
260:The first is the
197:electric vehicles
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1054:on 2018-09-08.
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1076:. Retrieved
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969:. gizmag.com
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949:. Retrieved
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689:. Retrieved
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580:City, Urban
467:
431:
420:Applications
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392:transmission
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86:by removing
82:Please help
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36:Please help
33:
802:. Elsevier.
756:Motor Trend
596:continuous
571:continuous
546:continuous
520:continuous
497:Gear width
488:Introduced
438:derailleurs
345:power plant
321:shear force
211:Mechanical
1105:Categories
1078:2011-07-28
973:2011-07-28
951:2009-12-05
926:2011-07-28
879:2011-07-28
857:2011-07-29
826:2012-06-08
784:2011-07-28
761:2011-07-28
691:2011-07-28
670:References
585:Fallbrook
560:Fallbrook
534:Fallbrook
508:Fallbrook
440:and other
396:hydraulics
251:concentric
238:transition
151:April 2021
84:improve it
39:improve it
1121:Hub gears
1006:Bicycling
323:and thus
301:pressures
274:overdrive
262:geometric
213:variators
104:July 2018
45:talk page
664:Variator
648:See also
503:Purpose
485:Product
463:commuter
446:bicycles
407:coplanar
317:traction
195:, light
494:Speeds
461:-, and
459:comfort
455:cruiser
450:Rohloff
403:coaxial
383:drive.
365:tooling
313:elastic
305:spheres
240:to any
207:History
141:updated
1074:. 2007
900:
482:Brand
325:torque
311:to an
278:torque
266:sphere
227:Design
921:(PDF)
851:(PDF)
752:(PDF)
591:2015
566:2015
555:City
543:2015
540:2010
529:City
517:2010
514:2007
282:speed
247:idler
242:ratio
233:balls
898:ISBN
405:and
353:only
280:and
457:-,
349:may
1107::
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
