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I have one of these. We first put it on my wife’s bike. She is a mechanical engineer and was fascinated with the design. Although she experienced no issues, she quickly noticed the appreciable friction compared to my bike built with a simple coaster brake. Either of us coasting down the hill on her bike was slower than the other. One can sense the friction by putting the bike on a stand and spinning the wheel. Much more than my Shimano coaster brake.

We just swapped rear wheels so now I have this on my bike. I am larger and stronger than my wife and can better deal with the friction. I hope the friction lessens as I put miles on the bike commuting to work.

My sense is that if the weight and friction were less then this hub would make a great hub instead of just a good hub. So far no problems.

Larry

I’m rather surprised by Larry’s comments regarding efficiency, and Bob’s for that matter.

My wife and I live carfree with kids and put around 15,000 miles on our bikes per year. We have bikes with derailleurs, a bike with an alfine and a bike with a nuvinci. In both our riding experience, which we’ve got around 6,000 miles on the nuvinci now, it is at least as efficient as same bike with derailleur, and I generally keep our drivetrains in very good condition, so we’re not talking neglected derailleur.

I can also say that it is our favorite drivetrain, and in time as others wear out, I wouldn’t be at all surprised if they were displaced by nuvinci’s.

They are incredibly smooth, quiet, durable, NO maintenance. I would already had to tear down and lube an alfine two times by now or lube a rohloff two times as well. meanwhile the nuvinci just keeps on cruising along smooth as can be without a single hiccup along the way.

Initial review of Nuvinci N360 on a recumbent tandem.
After one week/100 miles.

Bike ‘specs:
BikeE E2 recumbent tandem
rear shock
weighing in at 75 pounds with tools, waterbottles and lights
over 400 pounds of bike, riders and backpacks
(that’s over 180 kilos for you Unamericans)
set up as a daily commuter in the Berkeley, CA USA area
70-100 miles per week
Nuvinci N360 hub
20″ rear wheel, laced 1-cross
Install and wheelbuild by El Sobrante Cyclery, 94803
(thanks, Ken!)
32 tooth and 48t chainrings
18t rear cog
deraileur acting as a chain tensioner

Summary:
The Nuvinci N360 seems very well constructed, is viscerally pleasant to ride, idiot-proof and seamless to operate and can never miss a shift. It suffers the demerits of heavy weight (around 4 pounds), and relative inefficiency compared to a sprocket drive (I estimate 80% as efficient). I recommend it highly for low-maintenance cruiser/commuter use, non-competitive tandems, and especially, for recumbent tandems, but I don’t recommend it for going fast. If you ever see one on a bike, you’ve gotta try it.

Full story, with tangents:
Watching the drive train on our tandem wear away, daily, I knew it was soon headed for the great metal recycling bin in the sky. I like internal geared hubs (IGH) because of low maintenance and that they can downshift while stopped or stalled, which is a BIG deal on a recumbent (a ‘bent), where there’s no standing on the pedals to help regain forward movement again. I hoped the Nuvinci would also “solve” a tandem-specific issue of the Stoker and Captain coordinating getting off and on the power during shifts. With a standard IGH or sprocket drive, one has to ease up on the pedals in order to get a nice, quiet shift, and with a worn drivetrain, some pedal finesse is required to get certain shifts, such as down onto the granny ring. That all can be challenging for two people to coordinate, particularly on a hill or when a stall looms if choosing to obey a stop sign or avoid a sudden hazard (eg., from not obeying the stop sign). With the Nuvinci, however, the Captain can shift without notice and the ratio change will just happen seamlessly without upsetting anyone, since the drive is never disengaged.

On my tandems (yes, plural), I have the cranks set to be out-of-phase by 90 degrees between the Captain and Stoker. There is a chain that connects the two sets of cranks and one typically synchronises them in-phase so that both people’s feet move together, left/left,, right/right,, left/left,, etc, with essentially two big power pulses per rotation. However, the cranks can also be set out of phase: front left then rear left, front right then rear right, left, left, etc., to give four smaller power pulses per rotation. When I did this I noticed almost a gear cog-worth increase in power (we were climbing hills in the next higher gear than usual). This is on both the normal tandem and the ‘bent one, which has a rear shock that will compress a little with each power pulse. In addition to better performance, four little pulses should be easier on the drivetrain overall. On normal tandems one has to make sure both pedals are “up” on the inside of turns so that somebody doesn’t strike an inside pedal on the ground (catastrophy!). The pedals/cranks on the ‘bent tandem, however, are mounted so high that they can’t hit in a turn, so no worries no matter what their phase setup.

One issue I ran into when planning an internal geared hub was the amount of torque the hub can handle, which becomes an issue on a bike with two people torquing the drivetrain. Some manufacturers give input values for their hubs, either in an actual torque value or a chainring to sprocket ratio, eg., a 32t ring with a 16t cog gives a ratio of 2:1. Some hubs specify 2:1, Nuvinci says 1.8:1 and some don’t say at all, and I assume those ratios are for the strongest riders likely to use their hub. That minimum ratio and the reduction ratio of the lowest gear inside the hub is crucial as it says how steep a hill I can climb, and in Berkeley, we have hills! I figure that even though I’m not as strong as a pro rider, I may actually be able to spaz out the same peak torque once or twice, and with the stoker pedalling too (in phase), we could conceivably exceed pro torque in a moment of panic. But crank torque differs depending on whether one stands on the pedals or sits. Some back of the envelope calculations: just how much more torque does standing on the pedals impart than when sitting down and pedalling? Figure that if one is climbing a hill at the same speed then the power output is the same. Power is torque times rpm or pedalling cadence. Let’s say cadence while standing is 1/2 of sitting (say, 45 vs. 90). The cogs used for a standing climb are usually two to three higher (smaller) than sitting, for example a 24t down to a 16t. 16/24 is 2/3. 1/2 of 2/3 is 1/3. In other words, on the ‘bent where one can’t stand, a person may only be able to apply 1/3 of the torque as standing, and fudging a little more by assuming that one can push back into the seat a bit, maybe a person could put out 1/2 the torque. On the ‘bent tandem, both of us together sitting still won’t put out MORE torque than one person standing, and with an out-of-phase crank setup we’re putting out substantially less peak torque than one person standing. This also seems about right from how poorly we can climb hills compared with every normal bike we’ve ridden and with everyone who passes us up the hills… At any rate we’re running the 1.8:1 minimum input ratio (for a solo rider), to the Nuvinci, and can climb anything on our commute so the minimum is minimum enough for our needs.

One question I’ve read while researching the Nuvinci is, how much less efficient is it compared with a regular external sprocket drive? Nobody gives any numbers or data. Well, for over a week now we’ve climbed the hill to work in “full underdrive” of the N360 on the 32t ring, and it feels a bit easier than the 32/28 combo on the old drive. The gain ratio calculator on sheldonbrown.com says that 32/28 on our old setup with those wheels, etc, was a 1.6, while the N360 at full underdrive is at 1.2. Hmm, one is 75% of the other, which by my math gives a 25% loss as an “upper limit” for the hub. Up that hill with the N360 at full underdrive it is harder to pedal than the old 32/32, which has a gain ratio of 1.4, which when divided into 1.2 gives 86%, or a 14% loss as the “lower limit” for that hub. My guess is that the loss of the N360 is somewhere in the middle, around 20%, which is substantial; other internal geared hubs probably lose only half that. In other ratios the loss seems roughly the same or at least similar; the Nuvinci seems overall a tad slower than the old drive. Now, that said, after riding the N360 for a week, I don’t really care! Yes it feels slower, but the overall experience is WAY mellower than with the sprockets and deraileur. Look at the above numbers and realize we’ve left the realm of normal bikes and ride more of a human-powered land-yacht. It still takes about the same time to get to work, we don’t ever discuss the finer points of tandem communication while the chain skates around on the cassette, and we can power the pedals all the time instead of having these constant excuses to go slack, or struggling to avoid a shift. I can shift reactively instead of pro-actively; I don’t have to anticipate hills, stops or anything. Immediately it was obvious to both of us that this kind of drive on a non-racing tandem bike is the way to go. As Captain, I now constantly and almost subconsciously creep the ratio up or down to meet our immediate needs and to keep us working up a sweat (like a good DJ in a dance hall). With deraileur and cassette I was driving my Stoker nuts with all this compulsive shifting and the occasional ominous sound of the chain rattling, skipping and grinding from cog to cog, threatening a mis-shift, but with the Nuvinci nobody cares or really even notices the shifts. We just sit back, pedal away and enjoy the ride!

Would I recommend a N360? I sure wouldn’t get one for my solo bike: While I like the idea of an IGH, I have no problem shifting gears in a typical 3 or more-speed hub or cassette when I’m pedaling by myself. There would be no real advantage of the N360 and yet all the penalties of weight and drive inefficiency. I would recommend they try one, all those people who seem to use only one gear on their multi-speed bikes. We’ve all seen them – they ride around in one gear that has become so hook-worn that it probably couldn’t shift out if they wanted it to, while all the other cogs are pristine. These people seem to have an issue with shifting in general, maybe they fear the rattle of a perpetually out-of adjustment shifter or can’t quite get a clean shift with whatever arrangement and technique they suffer. The N360 is so fundamentally different to shift that they might really like it, and a N360 out of adjustment will still have a lot of range that’s easy to use. And I would unhesitatingly recommend that tandem riders, both normal and ‘bent, consider a Nuvinci. They/we have the problems that this particular IGH solves quite nicely.

So, Fallbrook, don’t miss out on marketing this hub to tandem users! Make whatever input ratio recommendations you need to insure the reliability of the hub for tandem use, specify out-of-phase cranks or whatever, but don’t miss this opportunity. This is a GREAT innovation for non-competitive tandem riders. I see you have this Harmony auto-shifter for the N360. If it is anything like the hub, I bet it has a huge, heavy battery, but works flawlessly. Get the Harmony to work on regular, non-electric-bikes and the two together would be awesome for tandems. There would be no arguing about the shifts, they would just happen! The ultimate maintenance-free bike? Put the N360 and Harmony on a shaft-drive comfort/commuter bike like the ones Dynamic sells, with a front generator hub to charge the Harmony battery and power lights, and run those thick, thorn-proof inner-tubes (that hold air for a month). It would be a bike almost as slow (and heavy) as a tortoise, but it would ride on forever and only need some air and a squirt of grease on the shaft every month/1000 miles! And I can’t wait for the next Nuvinci version.

If you’re in the Berkeley area and want to try the N360 on the land-yacht, give a shout to:
conboymike a t yahoo d o t com

Cheers,
Mike