fransb, you that is YOUR website? Are you selling this hub?
Yes it is MY site and no, I am not selling them. I just bought one of the Batavus bikes with NuVinci and love it. To give information and gather reviews I setup the site.
If you can read Dutch you'll see in my blog that I can second everything in the review (in post #43). The last remark about the shift box is solved by Batavus. Dutch bikes are mounted with full protection for chains and the rear axle.
Does anyone know the flange size of this hub? I'm not seriously thinking of doing it, but I'm pretty amused by the thought of what this would look like in a 16" rim. The spokes would be tiny. From the look of it you could mount an 8" tire directly on the hub, no rim required.
Really, the efficiency may lay in 97%... but only in 1:1 gear set as you go to lover and also to higher gear the efficiency of nuVinci draps rather dramaticaly to 84%... ( www.nrel.gov/docs/fy05osti/38212.pdf ) This is inherited to balls used as transmission mean. Plates pressed on balls will slip in lover and higher than 1:1 gear - the lover or higher gear ratio the higher will be twistting slip. Because plates are going closer to axis of balls. This will be problem in every system containing balls. And this is not torsional slip which can be lovered to very low values.
I saw better system which would have much lover twisting slip. http://cvt.com.sapo.pt/MCVT/MCVT.htm It uses lenticular planets which lovers this kind of slip (but not entirely eliminates it). It also has potential to have overal range of gear ratios higher than 350%... mayby as high as 800 % . I tried to simulate it with my brother who is mechanical engineer. We constructed lenticular transmission in computer and it went to be heavy, around 10kg, but that was without any optimisation for weight. I'm confident we could cut it down to 3kg using aluminium(duraluminium) on all not stressed materials. But trying to build it would be too costly.
So I thing, you have either to use clasical derailer (with middrive if necessary) or rohloff. Weared Rohloff (not new one- after around 500km are all parts weared to peak efficiency) can have efficiency from 95% to 99% in direct gear(11) http://www.rohloff.de/en/technical/s...ncy/index.html Only thing why not to use Rohloff hub is maybe the price
+1, I do not see the NuVinci as comparable to the Ripoff -- err, Rohloff.
C
I wonder if anybody who thinks that the Rohloff is too expensive has considered that maybe its that way because the US dollar is so depressed that by the time it makes it over here it, with our pathetic purchasing power it gets expensive?
It's a premium product but the exchange rate is making it expensive, not a rip-off.
IMHO. I have no idea how they make it for so little, it is that much of a mechanical marvel.
The Rohloff is expensive because there is no need for the company that makes it to make it cheaper. There is no other internal hub that has the range or the uniformity of development interval as has the Rohloff. It is very well designed and built, with a significant and growing track record for reliability and ease of maintenance. The Nuvinci is nothing close to the Rohloff; it has less range and is heavier. It is unsuited to MTB applications, for which the Rohloff was designed and excels. At best, Nuvinci will be able to compete with the SRAM, Sturmey, and Shimano 8-speed hubs in the "city" and cruiser market, and even then it doesn't compare favorably in either cost or weight to the other conventional hubs.
Rohloff is privately held and makes their product in a high-production-cost location. The cost of the hub will suffer relative dollar to Euro devaluation. Evidently they can sell every one that they make, so the price appears to be not too high.
Evidently they can sell every one that they make, so the price appears to be not too high.
Just like Brompton do, but unlike Rolhoff, Brompton has consistently failed to improve really poor features of their product, such as the brakes, the narrow gearing, and the collapsing rear end (collapsing when you lift the bike). Really small investments could improve these features, and yet they fail to make the changes.
Just like Brompton do, but unlike Rolhoff, Brompton has consistently failed to improve really poor features of their product, such as the brakes, the narrow gearing, and the collapsing rear end (collapsing when you lift the bike). Really small investments could improve these features, and yet they fail to make the changes.
The "collapsing" rear end is an integral feature of the Brompton's suspension. The speed of folding depends on it and the flexible contact with the rubber suspension bearing. I suppose it could be a problem if you wanted to lift the bike in the fully extended form as the rear triangle would flop down. I think they don't see this as a "problem" so much as a feature integral to the bike's design.
The brakes have been improved to the degree that they now have dual-pivot sets front and rear. These are available as an upgrade option on the ALC versions, but I don't know about the "stock" models. V-brakes would be nice, but that might affect foldability with the difference in cable placement. A front hub brake would reduce options like the generator hub. Discs require a wider hub, again compromising foldability and, with the smaller size required in the front dropout are probably not even possible in the front. There are already issues of heat dissipation and hub failure with disc-brake generator hubs on full-sized bikes and that would only be worse on a reduced-size folder hub.
The narrow gearing issue has at least one solution. A wider-geared hub, of which there are some available, including the Sturmey 8-speed, and the use of a Schlumpf Mountain Drive at the chainring. The latter is an upgrade option through some dealers already.
Really, the efficiency may lay in 97%... but only in 1:1 gear set as you go to lover and also to higher gear the efficiency of nuVinci draps rather dramaticaly to 84%... ( www.nrel.gov/docs/fy05osti/38212.pdf ) This is inherited to balls used as transmission mean. Plates pressed on balls will slip in lover and higher than 1:1 gear - the lover or higher gear ratio the higher will be twistting slip. Because plates are going closer to axis of balls. This will be problem in every system containing balls. And this is not torsional slip which can be lovered to very low values.
I'm not sure how to read the table at page 7, but it looks like in lower gear the efficiency drops to 84% (at ratio 0.44; the bike-hub goes from 0.5 to 1.75, so in fact the efficiency will be a bit higher ~ 86%), but at low gears the human efficiency also is not that good, so I don't think the efficiency problem is very big.
I wonder if anybody who thinks that the Rohloff is too expensive has considered that maybe its that way because the US dollar is so depressed that by the time it makes it over here it, with our pathetic purchasing power it gets expensive?
It's a premium product but the exchange rate is making it expensive, not a rip-off.
IMHO. I have no idea how they make it for so little, it is that much of a mechanical marvel.
Dave
It has been quite expensive related to other hubs/drivetrains for quite some time. My guess is that most people are simply comparing some personal assessment of Rohloff qualities/value to price to Brand X hub qualities/value.
Regardless, I do agree with your view that the hub is a wonderful device. (I do not possess one)
Just like Brompton do, but unlike Rolhoff, Brompton has consistently failed to improve really poor features of their product, such as the brakes, the narrow gearing, and the collapsing rear end (collapsing when you lift the bike). Really small investments could improve these features, and yet they fail to make the changes.
I agree with EvilV ... what irks me about Brompton is that a few small changes could make their bikes considerably better. I have tried modified Bromptons with v-brakes and it did not seem to affect the fold nor the cabling in any negative way. Note, I did not measure the fold. The bike performed better and one could use a standard v-brake found in any bike shop unlike the Brompton dual pivot brakes.
Why not offer a SA 5-speed version with the rear derailer? It should fit into the present rear triangle. Or for that matter, make the rear dropout spacing one centimeter wider (approximately). Would that not allow for a wider variety hubs? It would make the fold technically wider (less than one cm) but provide many more options without making the fold perceptively wider.
I'm not sure how to read the table at page 7, but it looks like in lower gear the efficiency drops to 84% (at ratio 0.44; the bike-hub goes from 0.5 to 1.75, so in fact the efficiency will be a bit higher ~ 86%), but at low gears the human efficiency also is not that good, so I don't think the efficiency problem is very big.
No... you are not worse at efficiency by lower gears, you are worse at efficiency by low or high cadency of pedaling. Most efficient cadency is according many studies at around 90 rotation/minute.
"I recently took a brand new Sturmey SRF3 and drilled and tapped the aluminum hub shell 10-24 for a Sturmey HSA106 oil cap. It's an easy job before the hub is built into a wheel."
To revisit this lube issue for a moment: Has the SA 8 speed hub been around long enough to wear that "maintenance free" tag? Thanks
Two years in the bike market are like two months in the computer market, so this review of the NuVinci from 2007 is not that old in real terms. It is well-written, and for efficiency mavens, there is an interesting section on "pedaling dead spot".
I agree with EvilV ... what irks me about Brompton is that a few small changes could make their bikes considerably better. I have tried modified Bromptons with v-brakes and it did not seem to affect the fold nor the cabling in any negative way. Note, I did not measure the fold. The bike performed better and one could use a standard v-brake found in any bike shop unlike the Brompton dual pivot brakes.
Why not offer a SA 5-speed version with the rear derailer? It should fit into the present rear triangle. Or for that matter, make the rear dropout spacing one centimeter wider (approximately). Would that not allow for a wider variety hubs? It would make the fold technically wider (less than one cm) but provide many more options without making the fold perceptively wider.
Third parties sell a number of brompton enhancements including 135mm spaced rear triangle with derailler hanger (Which can fit standard cassette hubs) and front derailleur adaptor. Modded 18 or 20 speed bromptons are lighter, ride great and fold just fine. BUT there are no such options from manufactor... they are just making silly, expensive, but still heavy titanium bromptons.
Brompton bikes sell very well anyway.. so they are just feeling no need to innovate.
If there is some "space age" fluid creating the friction to drive this thing, I wonder how long it lasts before it fatigues and how much cost/effort is involved in replacing it. If this is intended to market to electric bikes and low-speed heavy beach cruisers then it has a (potentially) very high mileage and torque scenario as well as a low mileage low torque scenario it needs to cater to. Sounds great in theory, but I'd want to know maintenance before committing and I haven't seen to much about it yet.
This thread has been around for a long time and things change. Back in June of '07 I had written;
Originally Posted by MnHPVA Guy
If I lived in Europe, I'd rather have a SRAM iMotion 9. However the people at SRAM USA booth acted as is I must be simple minded for asking if it will be brought to the US.
They are convinced that Americans will never pay much for hub geared bikes. One SRAM guy told me they sold over 2,500,000 hub gears world wide, but less than 200 in the USA last year. Since they don't stock any parts, (Apparently figuring American mechanics are as dumb as our "leaders".) no one in their right mind would buy one. Catch 22- The don't stock parts or promote internal hubs because not enough people buy them. Nobody's buying them because they don't promote them or stock parts.
While I doubt the internal parts situation has changed, the iMotion 9 hub is now being imported into the USA. Your local bike shop can order you one from QBP. Make sure they order the shifter too. It doesn't come with the hub.
For now I'm sticking with my old 2 cable S5 Sturmey Archer hubs as I have, or can get, any parts I might need for them.
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Originally Posted by workingbike
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to 84%... 
which can be lovered to very low values.
. I tried to simulate it with my brother who is mechanical engineer. We constructed lenticular transmission in computer and it went to be heavy, around 10kg, but that was without any optimisation for weight. I'm confident we could cut it down to 3kg using aluminium(duraluminium) on all not stressed materials. But trying to build it would be too costly. 
