NuVinci Left Side Freewheel

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MattyCiii
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NuVinci Left Side Freewheel

Post by MattyCiii » Jun 30, 2012 9:52 am

I'm considering designing/producing a left-side freewheel adapter for the NuVinci N360. The intent would be to reduce noise and drag for designs like my folding Dahon Jetstream and the soon-to-be powered 2009 Norco A-Line

The idea is to replace the disc brake mount with a machined 6061 adapter that mates to a CSK35 sprag clutch. Here is the left side of the NuVinci with the disc adapter:
Image

Here's a slightly better view - the disc brake adapter sticks out about 14mm
Image
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Jun 30, 2012 9:53 am

Oops!
:oops:
I ment to hit "Preview", not "Submit"...
More to follow!
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Jun 30, 2012 10:12 am

The disc brake adapter is a module - it can be removed by way of a spanner that mates with the 8 tiny holes you see surrounding the disc brake hole pattern, then a different adapter (e.g., a roller brake adapter) can be fitted. Removed, the disc brake adapter looks like this:
Image

My plan would be to create the left side freewheel adapter, which one would install as a replacement to the existing brake adapter. It would mate - press fit - with the inside diameter of a CSK35 (or better, a CSK35pp) sprag clutch. I would have to also produce a part that mates with the outside of the sprag clutch, providing mount bolt holes for an off the shelf chainring (I'm thinking 110mm BCD).

Initial estimates show I can produce both parts at a decent cost - about $80 for the pair - as long as I buy at least 12. I'd be "buying" 2 of these, leaving 10 for sale to interested parties. Note, the "outer" part can easily have standard disc brake mount bolts drilled in it... their horizontal placement will be a bit off due to the width of the sprag clutch and mounting bracket, but nothing a few washers around the axle can't fix.

What problem am I trying to solve? Good question. The principal problem(s) I am trying to solve are:
1) Placing the freewheel as close as possible to the driven hub reduces friction. Compare this arrangement with that shown in my Dahon build: https://endless-sphere.com/forums/viewto ... 30#p603784. With a 13t freewheel and 53t sprocket, I turn the FW about 4 times with each wheel revolution. Moving the FW to the NuVinci brings that back to 1:1.
2) With 4 FW rotations to one wheel rotation, the FW makes a lot of noise! It's also closer to me/my ears, so that extra noise is easier to hear, and dampens somewhat my ability to hear overtaking cars.

Why a sprag clutch? This is a left side drive, so if I was to use a standard pawl based FW, choices are limited because it would have to be a left side drive FW. Conversely, the CSK-35 freewheeling direction is determined by which direction you press it on.

My questions to the forum:
1) Is this a sound design in concept? Is there a better way to do this?
2) Would anyone be interested in buying one of these kits? I'm very likely going to move forward with this, but if there are interested parties I'd want to include them on the design/review so that I produce a product that meets everyone's needs (within reason of course!)
Last edited by MattyCiii on Sep 15, 2013 9:21 am, edited 2 times in total.
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Jun 30, 2012 9:52 pm

One more picture to illustrate. Below you see an adapter to mate a 130mm BCD chainring adapter to a standard 44mm disc brake pattern. This one was made by FFR Trikes. It's a nice part, it'll allow left hand drive on any bike with disc brake mounts. What I'm looking to achieve would look very similar to this, but it (1) would be NuVinci specific (due to the modular brake adapters on the NuVinci, no other reason), and (2) would have a sprag clutch hiding there behind a standard six-bolt disc brake mount, bringing the freewheel that much closer to the hub

Image
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Jul 03, 2012 7:30 pm

OK, I'm going for it.

Step 1: Buy the brake adapter removal tool from Fallbrook, inc. I have one on order, about $100 shipped.
Step 2: Once it arrives, take the existing brake adapter off and get all the dimensions possible using calipers. I have a spare NuVinci I can do this with.

With precise dimensions I can move forward with design for the two-piece adapter set.

Thoughts, anyone?
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Aug 10, 2012 6:06 pm

Not a lot of interest apparently. I'll be going forward, but at my own slow pace.

I bought the Fallbrook tool to remove the brake interface. Works great of course.

I've designed 3d models for the two parts I need to build. I'll be outsourcing to emachineshop.com. The sweet spot for pricing is 8 parts - I'll definitely be using 3 to 4 of these sets, the rest I'll put up for sale when I complete them and prove they work. Or, they'll go into my "kinetic art" collection.

Here are the parts. I'll print and test mockups on the MakerBot, just to test fit and take all doubt out of the design.

Inner piece: This interfaces with the inside of the CSK-35 sprag clutch. I have holes drilled and tapped for set screws, I should probably machine in a flat for a key.
Image

Outer piece: Pressed on, again I maybe need to have a keyway milled in, but I have holes drilled & tapped for set screws. There are standard 44mm BCD for standard disc brakes to attach. The main outer diameter holes are on a 3.625" diameter circle. This pattern is (I think, and need to confirm) the pattern for #219 chain sprockets, and for some HTD belt sprockets.
Image

What do y'all think?
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by amberwolf » Aug 10, 2012 6:43 pm

Looks like it should work, though I am not totally familair with the 360 version of it. Personally I am a fan of keys/keyways, though I have seen failures of those under some applications--I think your sprag would probably fail first, though. :)

I haven't any need for such a thing simply because I would rather run my power *thru* the NV so I can have it change gears for me on my frequent full stops/starts--even with it's losses it should be more efficient to do that than to run single-gearing direct to the wheel, because of the huge amount of power it takes to startup my heavy bikes (especially when loaded with cargo).

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Aug 10, 2012 8:25 pm

Thanks AW, I respect your experience and views and appreciate your input.

Ultimately I'd like to use the NV as a jackshaft, as a place to mix pedal power and electric, then send it to a simple rear wheel with a single speed cog. That's on my mind as I design this. In my next build, I put the NV closer to the cranks as a jackshaft, keeping the weight more central. And, making the rear wheel more simple so it has less unsprung weight, and is easier to rebuild when spokes break or the rim wears down.

It will certainly work as a rear wheel with the NV as a hub... I'm designing this to work with either way.
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by amberwolf » Aug 10, 2012 10:18 pm

For similar reasons, on my NV equipped bike, it will also be a jackshaft, but it will have both motor and pedal power input to it's input shaft, and output from the NV will drive the suspended rear wheel. I hope to also use hte NV as the pivot point for hte swingarm, but still have to figure out how to make some adapters to thread onto it's shaft to ride the bearings on.

I have considered combining pedal and motor power at a separate jackshaft, but that is an efficiency hit I decided I dind't want to take.


I also considered putting only the pedals thru the NV, but since I almost never pedal unless there's no choice (because of my knees, mainly), I decided putting the motor thru it is a better idea, if I have to do only one of them. :) Then I would run the pedals at low gearing ratio to something like what you are creating. But it is easier for me to try to do it all thru the NV input side.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Aug 12, 2012 8:30 pm

This is what the inside of the NuVinci N360 brake interface looks like.
Image

And the inner surface of the modular brake mount. This is what I have to duplicate:
Image
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by Mainer » Oct 01, 2012 2:58 pm

Hi,

I'm very interested. I have been working on a similar idea, although using a left threaded reverse drive "SouthPaw freewheel.

I've attached a picture of the left threaded adapter that the FW would thread onto. The jury is still out on how the freewheel will hold up, although BMX'ers are notorious for being hard on stuff.

Just a tech question for you... does the bulged dome section that rise above the 6 bolt mount actually perform a function (like support an axle bearing) or does it just house a hub seal?

Thanks,

Davis

davis@bikeman.com
Attachments
LH adapter 006.JPG

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Oct 01, 2012 4:05 pm

Mainer wrote:Just a tech question for you... does the bulged dome section that rise above the 6 bolt mount actually perform a function (like support an axle bearing) or does it just house a hub seal?
Indeed that's just a seal, the dome itself is plastic.

Looks like that part you have pictured will bolt right into the disc brake mounts. The plastic dome, and its washer and retining nut should fit nicely inside the inner diameter of that part - but that part might still be "too tall" and have some clearance issues. You can possibly machine 4-6mm off the disc brake adapter to grab more space.

I've revised my design some - I'll post updated pictures when I get a chance.
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Dec 23, 2012 9:15 am

MattyCiii wrote:
Mainer wrote:Just a tech question for you... does the bulged dome section that rise above the 6 bolt mount actually perform a function (like support an axle bearing) or does it just house a hub seal?
Indeed that's just a seal, the dome itself is plastic.
About that dome...
Image
The hex nut you see is fixed in relation to the axle. The dome turns with the hub/disc brake adapter. So there's turning and a friction surface between the two - most likely between the washer under the nut, and the dome. That mating surface feels pretty slick, as if the dome is PTFE coated or something.

So any new design I execute on must keep this in mind. I'll need to accommodate this motion.
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Dec 23, 2012 9:27 am

I've been looking at this side project again. Here are a few things I've realized:

1. Somewhere above I talk about bolting a disc brake to the "outer" piece. This would of course be completely worthless, as that outer piece freewheels! :oops: So if I'm to have any possibility of being disc brake friendly at all, I need to have mounts on the "inner" piece.

2. If I use a CSK-40 (http://www.vxb.com/page/bearings/PROD/Kit12575), I get 260nm of torque handling, and a 40mm inner diameter to work with. The width is a rather large 22mm - right at the edge of the envelope I have to work in (pictured above - the existing disc brake adapter and "dome" together combine to 22mm wide). This keeps the dropout width correct, but makes disc brake mounting a challenge.

3. I can use one of these (http://www.vxb.com/page/bearings/PROD/Thrust/Kit8670) to functionally replace the dome (see above post). This can be countersunk into the "inner" piece.
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Jan 06, 2013 6:43 pm

I went ahead and purchased the CSK40pp sprag clutch and a couple of the axial bearings I linked to in the last post. With the help of 900Steve, I'll be building a one-off implementation of this left side freewheel system and mounting it to the MENSTRUAL Cycle to road test the system. Nothing like building something then throwing a few kilowatts of power at it to see how it holds up!
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Jan 16, 2013 7:14 pm

Parts arrived. Pictures and notes:

Here are the CSK-40 sprag clutch and the axial bearing
Image

The bearing is 3 separate parts meant to be stacked: Image
Image

Here are the critical dimensions of these two components:
Image
Image

And a section view of the piece that interfaces with the NuVinci and the inner race of the sprag clutch:
Image
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Jan 19, 2013 2:10 pm

I'm able to move this project forward with the help of 900Steve. He's got the skills and the tools to machine stuff.

Here are a couple quick photos of a test piece he did. It's a test run of the bottom profile - and fits really nicely!

Image

Image
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by dbaker » Feb 03, 2013 2:09 pm

Very nice work :mrgreen:

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Re: NuVinci Left Side Freewheel

Post by bobc » Feb 03, 2013 3:58 pm

Hi Matt,
I used a couple of small cheap sprags on a reverse select gear system for my bike. I've long since ditched the system because the sprags dragged quite a lot (= poor efficiency for me), it was noisy and I don't actually need the low gear. The drag of the small sprags was unexpectedly high; considerably more than a pawl freewheel. So I'd expect the bike to be slightly harder to pedal (mind you, nuvincis drag a bit too...;^). I do get the clicking of the motor drive freewheel when I'm pedalling (whereas the sprag would be silent) but that's a pretty quiet noise compared to the outrunner when I'm motoring!
It's pretty easy to turn a disc mounting down to screw a LH thread freewheel on - I modified a discbrake rear hub thus this very morning for a trike project and it took less than an hour (thread and all). I just turn 8 to 10 mm of 35mm diameter where the brake disc screwholes used to be & screw- turn from there.
The other factor is cost - a LHT freewheel is £5.99 or £9.99 (if you can't find one on offer...) A big sprag of any quality will be several times that...
Just realised I had a picture - you can see the brake mount turned down. You can also see 2 12mm sprags which are now in my own "kinetic art" museum...
Image

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Feb 03, 2013 6:52 pm

Really great thoughts and info Bob, thanks for sharing!

I was quite frankly afraid of doing threads at 1.375" diameter in LH. Still am to be honest. But I'm not the machinist here, my good friend Steve is. It's certainly worth thought. If nothing else it'll make for a smaller width of the whole assembly - which is great because with my present design I'm rapidly running out of width.
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by bobc » Feb 03, 2013 7:30 pm

Sorry if I sounded negative, there's some lovely machining going on above (it is so nice when things are made & fit properly.....) Regarding screw turning - it's fairly scary if you've not done it before, but the thread diameter makes no difference - bigger is easier really, left hand or right hand thread no difference.
BTW I always bolted a larger diameter laser cut sprocket onto the freewheel teeth, I sold a batch of 80 tooth sprockets on here when my laser cutters made 8 and I had asked for 1 - they were just a tenner each (£10).
I'll be interested to hear what the big sprag is like in use - my little ones were rather stiff in the freewheel direction (and they didn't necessarily loosen up, quite the contrary in fact in one case) but on the plus side were totally silent and no discernable backlash. You can get quite a clank from the freewheel when it takes up drive.

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Feb 03, 2013 8:19 pm

bobc wrote:Sorry if I sounded negative...
Not at all! And I genuinely feel you've opened my eyes to options I had previously dismissed. I sincerely appreciate you chiming in.
Thanks,
Matt
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by Miles » Feb 03, 2013 9:27 pm

Bob & Matt,

Stieber specify a drag torque of 0.007Nm for the CSK12 and 0.07Nm for the CSK40. I guess the Chinese ones could be worse than that....

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Re: NuVinci Left Side Freewheel

Post by MattyCiii » Feb 04, 2013 9:53 pm

THANKS Miles.
The CSK-40 turns easily - but certainly does not spin (like a traditional freewheel can).

The #1 design goal of this project (by a wide margin) is to not have that section of chain spinning while I pedal. A freewheel can achieve that goal just as a sprag clutch.

I'll have to talk to my machinist ;)

That said I already own the CSK-40. The novelty factor is calling to me...
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.
3rd build (just started): Scratch build ultimate utility bike. Based on a common power module using a NuVinci left side freewheel.

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Re: NuVinci Left Side Freewheel

Post by Miles » Feb 05, 2013 4:30 am

I wouldn't worry about the drag torque of the CSK40. You'll find freewheels which are better and worse than it. At 250rpm it's only going to take 2 or 3 watts........ It's quite heavy compared to a freewheel, though....but given the weight of the NuVinci... :)

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