NuVinci built this really cool CVT in 2015 called the N380 which they say can take a whopping 350 Watts of power (as long as it’s not a cargo bike, then you can only get a measly 250W). I’m not going to waste your time telling you about how this thing works except to say that there are lots of REALLY BIG BALLS that have a funny little cage and some incredibly strange fluid. When the fluid is under high pressure it acts just like a solid and by changing the angle of these balls you can have a Continuously Variable Transmission that gives you essentially an infinite number of gears for only about $250 (I paid $252 shipped on sale but I can’t find it for sale anywhere right now, the retail is over $350). The N380 is the latest and greatest incarnation of the older N360 with about 20% more ‘range’. There is also the N330 released in 2015 as well, which is slightly cheaper and has less range (330%), but the exact same weight as the N380. The specs for both the N330 and N380 can be found on Fallbrooktech’s website here. The N380 CVT weighs in at about 5.4lbs and looks a lot like a hub motor that you will have to lace up yourself, which is a major PITA that everyone should suffer through at least once in their life.So what did I think? The first time I took it out I had problems because the install wasn’t done right. The 2nd time I took it out I had more problems because I am STILL an idiot. The last time I took it out I had so much fun I rode with my giant 25lb 25Ah battery for so long that I literally could not sit down when I was done riding. I guess that is high praise, at least from my hiney it is.
I still feel like the Nexus 3 IGH (full review here) is the ultimate trail riding IGH for fat bikes. It costs about $125 shipped for everything and besides the PITA of lacing the rim up, the install is a real snap. I’ve been beating the hell out of my Nexus 3 in plenty of gnarly riding and the hub has made really some strange noises (that sound like the smoke monster from Lost) but it has yet to fail. IGH are particularly suited for fat bikes as you don’t have to worry about sand and snow and ice mucking up your derailleur.
The N380 is a totally different beast than the Nexus 3. When you do something that you’re really not supposed to do (like start moving from a stop with full power on a 20 degree uphill grade) instead of getting the grinding gears the balls will just slip a little. This is not a real problem unless things inside get too hot, the magic fluid leaks out or something really breaks. The N380 is rated for 350W(max) but I am running it full-bore with a 750W nominal BBS02 at 59v which puts out well over 1300 watts peak when I really torque on it (and I do). So let me get this right, you are running this N380 at 4x the power that it is allowed to run this CVT at? Yep, I don’t care, I live to destroy your delicate ebike products. *evil laugh*
So what will happen if I break the CVT and I want it replaced? The jokers in the support dept of NuVinci already know me by name (oh yeah that fricking guy who keeps stealing our search engine rankings and loves to hear himself type?) and will most likely laugh me off the phone. That’s OK because I’m used to it. I bought this almost new car once and then after 5 years and 60,000 miles it wasn’t running right so I took it back to the dealer and asked for it to be fixed under ‘warranty’. They took one look at the oil filter which was a OEM filter and asked if I had ever changed the oil. I said, “What you have to change the oil? You gotta be kidding me, isn’t that covered under warranty?” They said NO and I decided at that moment to NEVER BUY A NEW CAR AGAIN. It’s all a scam and they don’t even give you free oil filters. Long story short I learned my lesson and since then I have learned to religiously change my oil every 59,999 miles without fail. (true story)
The hardest part of the N380 install was getting the gearing just right between the BBS02 and the CVT. Someone who was crazy on the internet who got my email address said that they were using BBS02\N380 combo with a 34T on the front and a 18T on the rear cog so I tried that first. It was geared WAY too low so I switched it around to a 42T Lekkie Chainring on the front (with 4mm spacers) and a 22T cog on the rear which for singletrack trail riding is perfect. If you want to ride only on the road and not in the woods then you will need to subtract 4 teeth from the cog and use a 18T cog to get the highest pedal-able top speed. With the 42T/22T combo I could climb 20-degree grades with ease and still get darn close to 30 mph on the flats (but RPM’s at top speed were too fast to comfortably pedal along with). For all you spandex-clad superheroes with a 42T/18T combo you will be able to pedal along comfortably at 30mph and even on the downhills.I added the N380 to Duh Banana Bike which was one of my lightest builds at a svelte 41lbs without a battery. Adding the hub and cables and shifter pushed it up almost another 5lbs which is still damn light for a <$1000 mid drive ebike that puts out 1300+ watts of peak power with a CVT & 4 inch tires. If you look at the miserable wasteland that is the commercial electric fatbike offerings in the USA you will find nothing else that even comes close. I built the rim with a single cross pattern and with all the 213mm 13 gauge spoke heads on the same side. This is something that the ancient N171 manual said to do that I liked so I carried it over to this hub build. Speaking of the N171, that hub is actually rated for 750W and there are people who regularly run several thousand watts through those CVT’s on a regular basis. The biggest problem with the N171 is that they are insanely heavy at 8.7lbs and incredibly hard to find as they were discontinued 5 years ago.
I had a lot of problems doing the install for the N380 that I’ll go into detail about here. I couldn’t actually find a manual for the old manual twisty shift system, as everything I could find on the N380 seemed to be focused on the new electronic Harmony system. Getting the adjuster to line up properly took me
a few 25 tries and a lot of hair (because I was pulling it all out). The tricky part is that the adjuster has to have the full range, but you can’t easily tell if it has the whole range because it will only turn about 1/2 way around until it gets stuck and you have to spin the axle a little so it can go the rest of the way. After a lot of finagling, I got it mostly figured out. The other problem is that it is counter-intuitive which cable goes where for the higher\lower gears. I accidently got them swapped around so that when I want to go fast the cute little orange plastic dude is climbing the hill. Unfortudently I had already clipped the cables and terminated them so I had to swap them around, then one of them was cut too short *arrrrrrgggg*. In the end, I cobbled it together and you can’t tell from the pictures how bad it really is. I also had to space out the Lekkie Bling-Ring to clear the intrusive chainstay and I had to build a spacer out of ground down washers held in place by hot glue so I could mount it properly. The Lekkie gave me a very clean chain line and I only had one chain derailment on my third time out. The heavy KMC single speed BMX chain will probably never break from these measly power levels.
So now that I’ve tried the N380 and a BBS02 would I recommend it? The problem is that the N380 is much more suited to the 1000W BBSHD which can generate some real power at normal pedaling cadences. The BBS02 needs to spin pretty fast on anything steeper than a 5-degree grade or you risk frying your controller. The BBSHD was born to run at full power (and more) at normal pedaling cadences so you don’t have to downshift so much when you hit hills. The biggest problem is that the BBSHD is going to shred this little CVT in no time flat (1500W+), and I even feel bad about using it at BBS02 power levels (Someone should call the People for the Ethical Treatment of Bicycle Components). There was also 3 major disadvantages to this CVT
- When you are in a higher gear and the CVT is under serious load and you are not holding the twist grip tight the N380 tends to slip into a lower gear on its own. I found this to be pretty annoying. So annoying that I’m actually taking the time to write about it.
- When the CVT is under serious load you can’t actually shift into a higher gear which is also really annoying (see #1).
- It’s expensive and heavy (wait that’s two) and a pain to install, expect to waste half a day on it (and that’s three making a total of 5 major disadvantages, not just 3).
For singletrack trail riding you don’t really need an infinite number of gears, you basically only need 3 and you just adjust your pedaling cadence to fit the situation. This all changes when you are riding on the road, I found when riding on a normal road at higher speeds (like 25+mph) that I really liked being able to adjust my gearing to get the perfect pedaling cadence. I can see how this would be massively appealing to road cyclists from a comfort perspective. The problem is that I don’t know any self-respecting road cyclist who would be willing to trade the eternal perfect pedaling cadence for an extra 5 lbs on his bike.
Every weight weenie will have to make that decision on their own accord. The Nexus 3 added about 1lb to the weight of my bike but the N380 adds almost 5lbs.
Update: I met a guy who burned through two N360’s then also caused a N380 to leak by running them with a BBSHD with default Luna programming. If you want to try to make this work make sure your throttle is set to Speed mode (not current) and the Start Current is set to 1% on both the PAS and throttle page then maybe, just maybe your N380 will survive. If you’re using a BBSHD you might want to opt for the heavier duty N171 CVT.
How depressing it must be for the folks at Fallbrook Tech to do a google search for ‘Nuvinci N380‘ and have my crappy website come up in fourth place. There has to be some way they can argue to get me removed from all Google search engine rankings. Maybe some caring reader here can start a petition. I’ll be the first to sign.
As soon as I destroy this CVT I’ll write all about it right here (unless they give me another one for free to destroy just to shut me up) : ________________________