+1
All CVT's use friction. Standard transmissions use gears so the only way they would ever slip is to break off the teeth. That bicycle CVT has balls riding in cones so there is very little friction surface for power transfer. I bet someone with the performance level of Lance could make that thing slip.

Like lots of people on this thread I was interested in this hub, but also a bit suspicious, after all bike CVT systems have a history of vapourware.

So, the only way to find out was to get hold of one.

Luckily due to the weak dollar I managed to get hold of a MK1 (more on that later) hub for a reasonable price. This was laced to a 406 rim to go on my Dahon minibike, rigged up for commuting.

My commute is 8 miles each way over a small hill with a gravel tow path and some heavy city traffic thrown in.

I liked it a lot.

Here's a mini review to give people something to discuss.

Weight: It's heavy, somewhere over 4kg just for the hub. When riding you don't notice the weight, it's low down and behind you. The only time you notice it is when you actually pick the bike up.

Friction and losses: Ok, there are some, this will never be able to be as efficient as a clean, well adjusted single speed or even a derailleur set up, HOWEVER, it's no worse than any hubs I've ridden and perfectly acceptable for non-racing use. It does prefer being spun to mashing but I've never managed to get it to slip (I'm the wrong side of 100kg)

Range: The range is 350%, compared to

Like lots of people on this thread I was interested in this hub, but also a bit suspicious, after all bike CVT systems have a history of vapourware.

So, the only way to find out was to get hold of one.

Luckily due to the weak dollar I managed to get hold of a MK1 (more on that later) hub for a reasonable price. This was laced to a 406 rim to go on my Dahon minibike, rigged up for commuting.

My commute is 8 miles each way over a small hill with a gravel tow path and some heavy city traffic thrown in.

I liked it a lot.

Here's a mini review to give people something to discuss.

Weight: It's heavy, somewhere over 4kg just for the hub. When riding you don't notice the weight, it's low down and behind you. The only time you notice it is when you actually pick the bike up.

Friction and losses: Ok, there are some, this hub will never be able to be as efficient as a clean, well adjusted single speed or even a dérailleur set up, HOWEVER, it's no worse than any hubs I've ridden and perfectly acceptable for non-racing use. It does prefer being spun to mashing but I've never managed to get it to slip (I'm the wrong side of 100kg)

Range: The range is 350%, (SRAM i-Motion 9 = 340%). This gives me 26 to 94 inches per crank revolution. At the very extremes (the last few %) of the range I think I can feel a drop in efficiency, certainly at the top end I go from zipping along with no effort to suddenly having to up my effort for not a huge increase in speed, but there again when i used a 91inch top on my dérailleur set up there was a noticeable increase in the effort too.
cker on their hands.

Customer service: After fitting the hub and riding around for a month a slight fluid leak appeared from the shifter rod. I emailed NuVinci to ask if this was normal. They replied the same day that they had had some leaks and had developed a replacement shift rod with improved sealing and that they would send me new one. Less than 48 hours later a new shift rod with a double O-Ring seal arrived (I live in London). Pretty impressive. A month later I notice a bit of fluid leaking from the main seal (not a rotating seal, the closure cap). Another email to NuVinci and they emailed back saying they would send the replacement unit over. A fortnight later a brand spanking new hub arrived. The first thing I noticed was the hub looked different. It was a Mk2, slightly smaller with some extra holes in the flange. Sure enough the hub is now under 4kg and noticeably lighter than the older hub so they're moving in the right direction. More importantly, I bought this hub knowing it was "cutting edge" technology and there may be a few teething problems, however the customer support from NuVinci has been excellent.

Overall: A good hub, it is too heavy and too expensive at the moment to really hit the big time, BUT i can see both falling as manufacturing and engineering know how ramp up. My ideal would be to drop a few % in the range (say to 300%) if that would allow them to get it down to 2kg or less and the price to the $100 mark. If they could manage that then they really will have a cracker of a hub.

The problem with traditional derailers and cassettes is the inability to shift at a stop. Not a big deal for recreational applications, a very big deal for utility applications, especially in an urban environment. This is the same advantage that any internal hub has (which are older and more traditional than derailer drive trains).

As for slushy, well... I was skeptical too, but the reports are that it is anything but. It operates very differently from traditional CVTs, which use friction belts and such. This looks like it should be a lot more efficient, and that's what people seem to be saying.