Note de ce sujet :
  • Moyenne : 0 (0 vote(s))
  • 1
  • 2
  • 3
  • 4
  • 5
Efficiency 1
#1
The following post is an entire topic copied from the discontinued NuVinci Forum. The majority is written by members of the old forum and not by me.

by jornole on Mon Nov 08, 2010 9:19 am

In every transmission is a power loss. What is the power loss in nuvinci N360?

Even in racing bikes with 21 gears or more there will be power loss in rotating small gearwheels and even the chain for transmitting the power there will be a powerloss.

It have not been possible for me or any member of my club to find anything technical data sheets covering this crucial data of efficiency.

When its possible to find a dealer I'll try out the new N360 hub, looks very promising.
Hope you can read my english

Best regard
Jørn Ole Spedtsberg

Re: Efficiency
by NuVinciSupport on Mon Nov 08, 2010 6:17 pm
Hi Jornole,

In regards to the efficiency loss, that is not information that we publish to the public. Unfortunately, you will not be able to find that information anywhere.

If you are interested in reading a user review, please check out the following link:
http://nuvinci.informe.com/forum/bicycle...-t437.html

A user took it upon himself to write up this review before he posted it to MTBR.com. He does efficiency in his review so this might help you in your quest for an answer.

For technical data sheets, you could find some information (although not about efficiency loss) on our website at:
http://www.fallbrooktech.com/08_Bike_Specs.asp

Otherwise, I think you will be quite pleased when you are able to actually try the hub as it should exceed your expectations.
Keep On Smooth Cruising
NuVinci Support

Re: Efficiency
by PantoJack on Mon May 09, 2011 8:57 pm
Hi NuVinci support,

To quote you, "In regards to the efficiency loss, that is not information that we publish to the public."

Why not? I love the idea of having (effective) continuously variable transmission (CVT) on a bicycle, but then I discover that you deliberately avoid publishing efficiency data!

If you were proud of the efficiencies achieved, I think you would publish the data.
If the efficiencies are lower than you'd hoped for and lower than competing (eg., derailleur and Rohloff hub) transmissions, then I think you would NOT publish the data.
If you've not tested for efficiency, then obviously you can't publish any data.

You don't publish the data, and your statement above seems to suggest that you have such data. I can therefore only judge that your otherwise seemingly-impressive transmission is inefficient.

[I have not done a time-consuming search of the forum on this subject.]

So come on... come clean. Either tell us you haven't carried out efficiency testing, or publish the results if you have! Publish the data! I challenge you! Publish it! ;O)

------------------------------

PS: It seems very strange (evasive) to answer someone's query about efficiency by pointing them to a review by someone who, by his own admission, is
- "not by any means an expert rider"
- "6'3", 215 lbs and likes to break things"
- is using a bike on which "There really isn't a single part... chosen for weight reduction or speed" and having "way-fatter-than-2.35... tire[s]"!

As useful and interesting as his review is, I hardly think he qualifies as someone particularly interested in the transmission's efficiency. Having said that, the comments he makes about efficiency and drag don't look very

encouraging:
- "I noticed that the wheel has a significant amount of extra drag on the truing stand compared to a basic freewheel hub, but it is not really noticeable on the bike and that resistance drops as the hub goes through it's

'break-in'."
- "The added resistance of the hub is barely noticeable, but it is there", and
- "when the bike was in full underdrive (32:36) and I was mashing up hill, I could "feel" the fluid in the hub"
- "You may perceive something as slipping, but I assure you that is not the case. Inefficiency via drag, sure, but you will not make it slip."

For many years I've wanted a bicycle with a good CVT. Given the critical importance of transmission efficiency when it comes to bicycles, do you think it is wise for me to buy one that may be inefficient off a company

that appears to be being evasive about that?

Re: Efficiency
by unsprung on Tue Oct 04, 2011 10:49 am

Just went for my first ride with n360 usually do 40k in 90 minutes today it took 165 minutes

Re: Efficiency
by CadenceKing on Tue Oct 04, 2011 7:46 pm

Hi Unsprung,

Wow! Your numbers are so strange that something must be loopy with the data, course/weather conditions, personal fitness, shifting methods, bike setup, timing etc. . . or there's more to the story. Please fill us in on the details!

-CadenceKing
He's a smooth operator,
smooth operator,
smooth operator,
smooth operator. . .

Re: Efficiency
by unsprung on Wed Oct 05, 2011 12:16 pm

My bad usually 110 minutes for circuit. But same bike, same road, same old motor, same heart rate, only changed back wheel and went for ride didn't stop and it took an hour longer. Are these figures different from yours?

Re: Efficiency
by unsprung on Thu Oct 06, 2011 1:20 am

The wheel doesn't spin around the axle freely, is this normal?

Re: Efficiency
by Rob_E on Thu Oct 06, 2011 3:43 pm

When I first got my hub, I was concerned because it seemed difficult to turn. When I laced the hub into the wheel, the added mass of the wheel made it turn more easily, but there still seemed to be enough drag to cause me concern. Once it was on the bike, it ceased to be an issue at all. I can feel no drag at all when pedaling, and on a downhill, I always coast on ahead of the group. Uphill is a different story, but I can't blame the hub for my poor climbing skills. I do feel that there may have been a brief break-in period, during which the hub got to spinning more easily, but if it existed, it was minor. If you are experiencing enough drag increase your ride time by a third, something is wrong. My ride time has only improved since adding the Nuvinci hub. Not that I'm crediting the hub with that, at least not directly. I love my bike, including the drivetrain, and I ride now more than ever, which has led to me being a stronger rider. Always being in the exact gear I want certainly doesn't hurt.

My 30-40 minute commute that I had on my traditionally-geared bike remained the same when I switched to the Nuvinci hub. I sometimes commute on a different bike, an old 3-speed, which adds a couple of minutes on to my commute, but that seems more about gear options, bike weight, and riding style than about drivetrain efficiency. If your 2 hour ride is now 3 hours, I think something is wrong.

I have to think that if you're really worried about efficiency, then adding a couple of pounds to your drivetrain would be unacceptable even if the hub had zero loss of efficiency. I took my "data" from people who used the hub and reported back on how they enjoyed. Actual numbers have no real life meaning to me, and won't until I can ride a number of bikes with known efficiency data and actually feel the difference. As it stands, I have ridden a number of bicycles, but have never noticed any inefficiencies that weren't addressed by common maintenance (oiling a chain, truing a wheel, etc.). That said I do wish that Nuvinci would be more forthcoming with efficiency data, and I think it's disingenuous to say "we're not going to tell you, but look at these positive results." If they had positive data, they would share it. I suspect that they feel, and I agree, that the numbers don't add any real value to the discussion compared to experience, but it's not they don't always choose the most straightforward way of expressing that.

Re: Efficiency
by drewjet on Thu Oct 06, 2011 4:03 pm

Here is some testing I did. this is with the N171 developer kit

I tested it out on my electrathon. This is currently set up as follows. 3 wheels, 2 yellowtop lead acid 12v batteries (24v) Etek brushed motor, total all up weight about 375 lbs, top speed about 28 MPH. With the Nuvinci set at a fixed point, geared for a top speed of about 28 MPH, acceleation was as follows, 0 to 10-MPH 5.1 seconds, 0 to 15-7.2 sec, 0 to 20-10.6 sec, 0 to 27-20.5 seconds, at 27 mph I let off the throttle and the CA said I used .493 AH. I redid the same test 3 times to get average of the numbers, they were all very close.

Next I redid the test having the Nuvinci in Auto mode, speeds were 0 to 10 in 2.6 Sec, 0 to 15-4.5 sec, 0 to 20 7.2 sec, and 0 to 27-13.8 sec. And only .425 AH used. Top speed also increased to 30 MPH. But really it could be set faster based on what you program it with, but the amp draw gets too high to be of any use to me.

Re: Efficiency
by drewjet on Tue Oct 18, 2011 5:09 pm

The tests were all done on the same day within minutes of each other. The results are in line with what I was expecting, maybe a little bit better than expected.
It makes sense to me and was the reason I bought the Nuvinci. By having gearing available it allows the motor to get to a high RPM sooner than a fixed gear, which is where a motor is more effecient.
Répondre
#2
I managed to "Rip" a good part of the forum before it got closed but it will have to be cleaned-up and saved as static pages before I can post it online...

It's going to take a lot of time but I will get through it. They did not even answer my E-mails when I asked for a copy of the database before it's gone.
-
Si ça a déjà été fait, je peux le faire
Si ça n'a jamais été fait, donnez-moi juste le temps de trouver comment !


Répondre


Atteindre :


Utilisateur(s) parcourant ce sujet : 1 visiteur(s)