Overview of the NuVinci Continuously Variable Transmission Hub for Electric Bikes

Court

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Hi guys! I'm moving some content off of the main site and into the most relevant categories of the forum. This post was originally made on September 1st 2012:

The NuNinci Continuously Variable Transmission (CVT) hub has started popping up in the electric bike world more and more because of it’s unique abilities to eliminate gear steps, change seamlessly at rest and reduce the chances of having a chain fall off. I had the chance to interview a NuVinci representative, Al, and learn more about the product and how it works with ebikes as either an option or an after-market addition.

The NuVinci N360 is offered as an upgrade option on bikes like the Evelo Aries which has a mid-drive system. Since the NuVinci hub can shift under load and at rest, it enables the user to easily go from a harder gear used at higher speeds to an easier one as the rider encounters a stop sign or light without having to plan ahead. The downside is, this option costs an extra $400 and adds ~5lbs in the case of the Evelo bikes. In my interview with Al from NuVinci however, it sounds like the weight of the hub is comparable to a standard eight speed chainring set.

NuVinci hubs are sealed for life and rely on a two cable system controlled either manually or via electronic shifters. The product is warrantied for two years.


The NuVinci N360 CVT works with two styles of shifters. The less expensive manual grip shifter lets the rider choose how hard they want to pedal as they ride by turning a grip shifter. This action activates a two cable system that changes the gear. The fancier alternative is an auto shifter system called “Harmony” that lets the rider decide what cadence they want to pedal at, set it, then let the bike adapt as terrain changes. So with Harmony, in a sense the rider should always be pedaling with the same force at the same speed and the bike will just adapt. Depending on terrain, the rider will end up going faster or slower but pedaling will remain constant.

If you can’t decide between the manual cable version or the Harmony auto shifter, NuVinci has a dual mode setup that includes both. We explored a European Kalkhoff electric bike with Panasonic motor and batteries that featured this setup, check it out in the video interview just above.

NuVinci’s parent company, Fallbrook Technologies, has been around for eight years and entered the bike scene five years ago. They offer products in Europe, Asia and the US and have recently begun offering technology solutions for trucks, busses and automotive. Their N360 manual shift system retails for ~$400 and is compatible with belt drive systems as well as chain drive. Having ridden these bikes myself, I love the smoothness of shifting, being able to shift at stop and the reduced maintenance, squeakiness and rust that a sealed solution offers. These benefits are enhanced further when paired with a belt drive system because it also won’t rust and is less likely to derail than traditional metal chains.

nuvinci-n360-cvt-hub-diagram.jpg


I also asked Al about how the company got it’s name and whether it was paying homage to Leonardo DaVinci, which he confirmed. Leanardo “was an inventor of mechanical devices and tried to make the human machine interaction better”. I think NuVinci is doing a great job with their products, following the same guiding principals Leonardo did.
 
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Court

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#2
Following are some of the original comments that were made on that post:

JAMES
Court, I wonder about the actual effective ratios of the Nuvinci hub. Does it complement the typical spread of a roadie or is it more like a three speed of yesteryear? Have you access to the numbers or perhaps an impression of the performance in terms of ratio? No doubt about it the mechanical system looks to be more reliable as to incidental malfunction (like loosing the chain, jumping gears etc.), and somewhat more durable as well. The smoothness and continuous variability are unmatched by chains of course, I am curious if some slippage is present or if the drive is ball locked completely. James

COURT
Hi James, great question here. I don’t have numbers on this but can give you a general impression based on my time riding the bike. I’d say it feels like a five sprocket cassette, the range feels limited. One of their sales and marketing messages is “unlimited gears” and maybe that’s sort of true when you very gently shift the CVT… you are technically getting many “speeds” but the range is limited. As far as durability, yeah you don’t lose the chain or get mashing but I haven’t used these off-road or for extended periods and I have heard some people say they were concerned about how it would hold up and that over-shifting – like twisting too hard – could cause damage over time and that they could be tricky to fix. The NuVinci hubs are definitely more expensive than traditional cassettes and they also add weight so I don’t think they’re the best candidate for trail riding to begin with. If you want an internally geared hub for that a Rohloff Speedhub might be more durable. I’d consider a NuVinci for in-town or urban riding and was excited to see it as an option on one of the new Grace MX2 electric bikes.

KARL
Court, love your videos. Keep it going. James and Court, here is some info I’ve uncovered recently: I think the NuVinci has a total range of 360%, hence the name “n360”. I believe it is 50% to 180%. It is wider than an 8-speed hub (Nexus/Alfine), almost as wide as Alfine 11, and definitely less wide than Rohloff 14-speed. NuVinci price seems more than Nexus/Alfine 8, similar to Alfine 11, and far cheaper than Rohloff. For durability, it might not be up to Rohloff robustness (or maybe it is???), but probably way ahead of Alfine 11. (Alfine 11 seems like a gamble from the user reviews.) I guess the Nexus/Alfine 8 are pretty durable, so it might be similar to that or even a little better. The Nexum/Alfine 8 get used off-road quite a bit. (You don’t really need super high gears when off-road, so they have just enough ratio range.) I bet NuVinci would be durable enough for off-road mountain biking, just from the reports I’ve read, the videos I’ve seen, and that it is being used in eBikes with mid-drive where high-torque is applied. There are quite a lot of videos showing NuVinci being used off-road aggressively. I don’t think you see many Alfine 11 hubs in eBikes or in off-road use. NuVinci weight is a little higher than the others, but not all that much when you consider the pretty high gear ratio and that the gear-spacing can’t be an issue anymore. Efficiency might be more of a concern, but it is somewhat countered by the fact that you can always be at your ideal cadence. And NuVinci is sealed for life and doesn’t need annual oil change or disassembly and re-grease. I’ve been researching internal-gear hubs for last few weeks and am considering my purchase options for a non-eBike project. I have no favoritism or affiliations and don’t own any of these yet. I’m just reporting the things I’ve learned on-line. I’ve considered some other hubs, too. SRAM 3-speed (but 7-, 8-, and 9-speed hubs are not on their web page anymore, so maybe discontinued). And Sturmey-Archer 3-speed, 5-speed, and 8-speed, but I just got an email from Sturmey-Archer (Sun Racing) North America that all their production is tied up with OEMs until at least Sept. I was considering Sturmey-Archer 5-speed in conjunction with Schlumpf 2-speed Mountain Drive bottom-bracket crank (40% and 100% ratios, no cables, heal-click shifting). That combo gave a fantastic gear range of 606% with very-nicely uniform gear spacing. It is a heavy solution, however. And like a Rohloff, the Schlumpf is pretty pricey. The Sturmeys are cheap. The Sturmey-Archer 5-speed is heavy, but durable and even recommended for rickshaw use. There is a YouTube video with a guy using Sturmey-Archer 2-speed “kick-shift” and Schlumpf. It’s a 4-speed total with zero cables. Coaster brake in back, so no cable for that either. If you want better braking, you add one cable for a front brake, I suppose. I was considering that too, but I tend to stay seated and shift a lot, and I live in a hilly area, and I need more total gear ratio than it would provide. But it was definitely cool. Anyway, hope some of this info is helpful.

COURT
Thanks for sharing your thoughts Karl! Feel free to provide the link of that YouTube video. I appreciate the feedback on each of these different systems and did see the Nexus Alfine 8 being used with the new Shimano STePs mid-drive ebike recently. I spoke with Pete from Electric Bike Report about his experience on it and he said it was super smooth but I found that shifting under load (or even the auto shift to level 3 when you stop) caused some crunching as I began pedaling. I think the NuVinci avoids this type of thing entirely.

LARRY
What e-bikes come with the NuVinci N-360 other than Evelo?

THOMAS RYAN
I have the NuVinci 360 on my Evelo Orion. While it works fine when the bike is turned on, when off, it adds a lot of drag to the riding experience and I am not able to achieve speeds and ease of riding as with a regular bike. Somewhat like riding with the rear brake partially on all the time. This also affects the top speed when motor is turned on and the Orion tops out at about 16-17 mph with a 138 pound rider.

COURT
Very interesting… I have noticed some drag on ebikes with gearless direct drive hub motors but thought that the NuVinci CVT freewheeled? What ebike do you ride with it?

THOMAS RYAN
I am riding the Evelo Orion. I live in an area with few hills. On one short incline I was ablr to get my Trex 7100 up to 20 mph in high geat. Very high cadence. On the ebike with power assist 5 and pedalling hard, could only get up to 18. I am not sure if all the drag is coming from the NuVinci or if the gearbox and motor offer resistance as well. In high gear, hard to get the cadence greater that 60 rpm. I dont have the resources but would be interesting to see how the bike performs on a “treadmii” where you could monitor all the parameters.

COURT
Interesting… I’ve seen dyno systems at some ebike design offices and they use this to measure power. I think the NuVinci CVT freewheels so it shouldn’t add drag, same with the motor on your bike, it might be the brake pads rubbing or the axles being overly tight. The Evelo Orion is often shipped direct and may not have gotten the same tuneup as an electric bike purchased from a shop where they build, grease and test with pro-level equipment. I’ve put a few ebikes together over the years and they seem to not ride as well or have mistakes (because I’m not a pro mechanic). I usually take them in for a tuneup at a regular bike shop but that does add to the cost, usually $60+.

THOMAS RYAN
My error on the Nuvinci drag comment. New bike and it did not oçcur to me that the brakes might not be properly adjusted. Rechecked and found a problem. Adjusted and wheel does spin freely now.

COURT
Awesome!! Thanks for the follow up Thomas, glad your bike has been tuned up and is now coasting smoothly :D

JOHN LAND
I loved that bike you first show on the video above. What is it? Looks sort of like an old Norton motorcycle or similar.
It has that N crest on the “gas tank”

COURT
Hi John! I’m not sure which brand that is… The bike looks like a red cruiser style bicycle with wood (or fake wood) accents. At first I thought maybe it was a New Belgium bike (this small brewery that gives out cruiser bikes to employees) but I cannot say for sure and I’m not sure how NuVinci would have gotten one… maybe the N was just added for them and it’s a custom bike? Sorry I can’t help more, if you figure it out please chime in and let me know!

JOHN LAND
Thanks for the reply Court….. definitely a custom job then. The canister could house the battery and motor i suspect. Makes me want to build something like it. hmmmm Thanks for all the good info, by the way. Your reviews are very insightful and thoughtful. best

COURT
Sure thing John, if you decide to build an ebike I highly suggest checking out e-RAD, they have a nice system that would interface with the NuVinci well (it’s a mid-drive motor). I’ve actually seen the motor built onto a bike with the NuVinci before and it worked great. Here are the different versions they sell.

BRAD
Is there a list of bikes available in the US that feature the “Harmony” or “H-sync” or any other automatic shifting/transmission, like the one shown in this video? On the Tempo website they state their bikes feature the Harmony system, but some of the images of the bicycles shown don’t appear to include the device used to control the shifting, so it’s hard to tell.

COURT
Hi Brad, I mostly hear about or see this drivetrain on demo bikes at events, never in person. I think it might be an upgrade option for some companies (like Tempo). I think Felt might have a model with it but I don’t know at the moment, I’ll poke around and reply back when I hear more :)

JOHN CONNOR
Ordered a Terratrek Rambler with a nuvinci cvt shifter and plan to use it on hard sand
lotide beach cruises of 10-15 miles and bike trails for 25+ rides. Planning on 24″ wheels but wonder if a 26″ rear wheel would allow a bit more speed although not really in a hurry! Any comments would be very welcome. thanks JC

COURT
Hi John! My experience with 24″ wheels is a bit limited, it’s a unique size because it lowers the standover height of the bike and provides more strength than 26″ or 28″ but might also impact pedal cadence (because the wheel turns more rotations in the same amount of distance). As for cruising faster, you’ll have a lower attack angle on 26″ which could roll over cracks and bumps a bit more comfortably. It takes more effort to get a 26″ or larger wheel rolling, but then it offers more momentum to keep you rolling. You’ll get a bit more surface area and traction with a larger wheel but sometimes if they are too large, the bike gets really long and you can even clip your toe on the tire or fender when turning sharp. This is all of the knowledge that I have, I hope some of it helps you ;)