RadioFlyer

Sounds like analog (if you'll allow the comparison) gearing where you can dial it in to your needs on the fly.

I'm so interested in it as the reviews here suggest it is the most durable, reliable, easy to use internal -- something I'd very much like to have on a dedicated commuter bike.

Way too heavy for my recreational roadie/mtb needs.

Allen

Internally geared, not auto shifting. The cool part is that it is a continuously variable transmission. It works with balls and some space age lubricant.
Here is Fallbrook's (the manufacturer) overview page.
And here they have some cross section videos if it working.

I have mine hanging on an electric assist cargo bike. Weight concerns were the first things to be tossed out the window on that bike.

bigbadwimp

I'll allow it.

That does sound pretty neat. No wonder they are $$$. Sounds like a great addition to any utility bike.

BarracksSi

That is a good comparison. It's like the volume knob on a home stereo where you can finely adjust the volume (CVT) versus a stepped volume control that only gives you one or two dozen choices (conventional gears).

MarkS

Continuously Variable Transmission means that you don't have to settle on a gear that's either a little too high or a little too low for your current needs. It means that, at least in theory, you can maintain the exact RPM and the same pedal force throughout a range of conditions. Some people find that idea very intriguing.

You can change gears from a dead stop. Because of that and because you're not skipping gears, and because its all sealed up, there's the hope that will get longer life out the hub than out of typical derailleur systems. There's also the the thought that CVT would be easier to learn and apply than derailleur systems. Just as automatic transmissions open ed up the world of driving to greater numbers of drivers, so CVT might expand the world of cycling to people who just can't get the hang of shifting.

nar

Actually, I think it's more like 350%

Cody Broken

Anyone buy that cheap ebay Nuvinci bike?

Allen

Fallbrook does not give a percentage, just states it is comparable to other internal hubs.
Sheldon Brown has it listed as 250%. It doesn't feel like it's more than 250%.

I_bRAD

how well does it work in the cold?

Allen

I'm in Georgia, haven't seen snow in years. It hasn't gone below freezing more than once or twice this year, sorry. Works fine in high heat and humidity, and in drought conditions.

nar

The range is 1.75 in high, down to .5 in low. 1.75 / .5 = 3.5. That's 350%.

Sheldon Brown

OK, so low gear is 100%, high gear is 350%.

350% - 100% = 250%. That's the _range_.

See also https://sheldonbrown.com/gears/internal

I just got one on my Greenspeed trike, but I've only had opportunity to ride it for a couple of miles so far. So far, I like it a LOT!

Sheldon "Digital Isn't Always Best" Brown

nar

Hi Sheldon - I think the hub itself has a range of 350%. If you include the sprockets in the equation it changes everything. For instance a 34 ring with a 17 freewheel: then in low you get .5 (hub) x 2 (sprockets) = 1 (one rev of the crank = 1 rev of the wheel, or 100%) and in high 1.75 (hub) x 2 (sprockets) = 3.5 (one rev of the crank = 3.5 revs of the wheel, or 350%). That is a total effective range of 350% - 100% = 250%.
Now lets say you choose a go-fast ring with 52 teeth and the same 17 tooth freewheel. In low you get .5 (hub) x 3 (ish, sprockets) = 1.5 (one rev of the crank = 1.5 revs of the wheel, or 150%) and in high 1.75 (hub) x 3 (ish, sprockets) = 5.25 (one rev of the crank = 5.25 revs of the wheel, or 525%). That's a total effective range of 525% - 150% = 375%.

AndrewP

I dont think they will be able to get the weight down, because very high forces have to be maintained between the driving parts to prevent them from slipping. This requires a very rigid (heavy) design. The range between the low end and top would be the same as 30 gear inches to 105 gear inches, which should be enough for most people.

Allen

Sheldon, what size wheel is on your Greenspeed? More accurately, do you know if I can lace a NuVinci onto a 20 inch rim? Thanks.

richardmasoner

Here's a handbuilt Titus equipped with the Nuvinci CVT hub:

grogee

I'm on the 'no' side of the fence. 5kg/11lb is too much of a price to pay for stepless transmission, not to mention $400+.

Humans are pretty tolerant of different cadence speeds so I'll stick to my stepped gears for now, at least until Nuvinci can lose 1/2 the weight of the hub.

Could be good for electric/pedal hybrids though, where you get a bit of help up the hills.

I know of a prototype small (petrol) vehicle that will be using a variation on this transmission.

Nobody has mentioned transfer efficiency yet? Any figures available?

NB: I've also read posts from users who have used this hub and have suffered fluid leaks... although I should temper this by saying the Nuvinci support was supposedly excellent. Having said that, it should really be 'fit and forget' at this price.

Maybe in the future we'll see bikes with this at half the weight and half the price - particularly if manufacturing volumes increase, and costs drop accordingly.

icedmocha 

FYI Costco has the Cadillac cruiser with Nuvince for about 450 right now.

BarracksSi

My LBS got one of these this week already built into a wheel, and one of the mechanics put it into his Surly 1x1. I got to take it for a test ride.

I broke it! Well, not really "broke", but somehow the shift actuator thing popped off of the axle and it was stuck in "top gear". Once I figured that out, I popped the actuator back on, and everything was A-OK.

It's heavy. Jeez, it's heavy. Picking up the bike with one hand means lifting it by the seat tube. The bike nearly balances at a point above the front of the rear tire -- lifting by the middle of the top tube will leave the rear wheel on the floor. I thought I could feel that it affected the handling of the bike. It's not like having a load on a rear rack, though, because it's so low on the bike.

It feels a bit squishy, strangely enough. Nothing bad, really, but instead of a *clunk* that you get with pedaling into a conventional freehub, the cranks squish for a couple degrees while the transmission takes a set. It shifts fine while on the move, yet does it better when you're not fully loading the pedals -- if you want to shift at a stop, don't do it while pressing on the forward pedal.

"Shift" isn't the right word, either. Maybe "adjust"...

The gear range seemed fine to me (didn't check the chainring & cog sizes, though). It went low enough for the climbs I'd see and fast enough for urban riding.

The shifter took a lot of twists of my wrist to go from one extreme to the other. I wonder if I would like being able to do it with three or four twists (I'm guessing 90 degrees each) instead of nine or ten.

When backpedaling, like when repositioning the pedals at a stop, the cranks spin quite freely, especially when compared to a derailleur setup. I often overspun it and had the pedals go past vertical.

It's really interesting. It's unlike any of my conventional bikes. I can pick any cadence that feels best while riding at any speed. It was like I was adjusting it to my body rather than adapting my cadence to a gear that's just close enough. CVTs in motor vehicles go for the same principle, adjusting the output while letting the engine run at its power peak.

I'll be keeping an eye on this particular hub. My next bike is probably coming with derailleurs, and if I wear them out, I really want to switch it to an IGH.

Allen

I've had mine for well over a year now and still love it.
It has been a "fit and forget" hub, and it's three and a quarter not four hundred plus in price.

I've put it through its paces on my electric longtail carrying heavy loads, and under high torque situations. I can't kill it and I've done my best.

I don't think I would put one on a strict commuter, but for a utility bike that will carry off size loads and needs single speed reliability, I think it is the perfect hub.

BarracksSi

AllenG, is it just me or does the shifter mechanism look fairly exposed as it hangs off the end of the hub?

I keep thinking that I may have knocked mine loose during that test ride. At least it didn't actually break off.

Allen

It may not be all the way seated.
Mine will still shift before it's all the way home.
They are a little of a PITA to release and reseat.

BarracksSi

Hmm, yeah, it may have not been seated right. It attaches very simply, though, which is why I was thinking that it was easy to knock back off.

It sure was easy to readjust and pop it back on, though. Spin the shifter to one end, turn the hub spindle by hand until it stops, then plug it back together.

rijwielenjacobs

i've also bought a nuvinci kit online to try it out and indeed, it is a heavy thing. Installation was no problem.

haven't had the time yet to try it out, waiting for the weather to get better