Converting QX100 to NuvinciN360

DavidJL

DavidJL

Well-Known Member
I am in the process of converting my QX100 to an N360 hub. I'm attempting to find a magic gear where I won't need a tensioner. 42-18 was close, but chain is a bit too long. Going to try 39-18 next. Used the FixMeUp! program to help find the right combo. Would really be cool if this works.
 
DavidJL

DavidJL

Well-Known Member
My first attempt was 34-18. The chain was ~1/4 inches too long. With 42-18, the chain is ~1/8 inches too long. As with any drive with just two sprockets, one does have to allow for about 3/8 inches free play, or the chain will bind.
 
B

BrianA

Active Member
I am puzzled as to why you are not using a chain tensioner and keeping the two chain rings up front. During my ownership of a MK1 Quest I experimented with a N360 hub. My experience was that the hub worked very well but I definitely needed to retain the original group of chain rings in order to have a wide enough gear ratios to cover all situations. In my case the Quest had three chain rings but I very rarely had to use the smallest (only on the very steep hills). Remember the hub adds a fair bit of extra weight and unless you are lucky enough to only ride on flat ground I think you would be better off keeping both chain rings and fitting a tensioner (no problem then with chain length). Another thing I should mention is that when the hub was first fitted to my original wheel by a local bike mechanic I suffered several broken spokes. This was caused by the fact that the hub on the N360 is much larger than the original hub resulting in the spokes not aligning correctly with the nipples. A better wheel builder solved this problem by easing out the holes in the rim to ensure that the nipples and spokes were correctly aligned. Something to watch out for.
 
DavidJL

DavidJL

Well-Known Member
I should have insisted that the LBS owner spec'ed 2-cross instead of 3-cross. If spokes start breaking, I will definitely rebuild it 2-cross. Currently, I am using 11-21 9-speed cassette with 34-50 chainrings, so the Nuvinci hub should give a bit wider range. I want to have nothing clamped on the front boom and a simple 2-sprocket setup. Took an old chainring and machined off the teeth to make a chain guard. Just received a chain tensioner if I should need to use it. I did try using a triple crank at one time, but the inner ring would not clear the boom pivot. Will be interesting to see how this project turns out. Will have to fire up the camera and take some pics.
 
ratz

ratz

Wielder of the Rubber Mallet
DavidJL said:
I should have insisted that the LBS owner spec'ed 2-cross instead of 3-cross. If spokes start breaking, I will definitely rebuild it 2-cross. Currently, I am using 11-21 9-speed cassette with 34-50 chainrings, so the Nuvinci hub should give a bit wider range. I want to have nothing clamped on the front boom and a simple 2-sprocket setup. Took an old chainring and machined off the teeth to make a chain guard. Just received a chain tensioner if I should need to use it. I did try using a triple crank at one time, but the inner ring would not clear the boom pivot. Will be interesting to see how this project turns out. Will have to fire up the camera and take some pics.
Click to expand...

Ok so having used a N360 for 2.5 years on a CT700; you will encounter one main problem without the tensioner (I know I tried a lot to get that pure setup). The QX100 uses a vertical style dropout; and to run without a chain tensioner the hub is expecting a single-speed style horizontal dropout with a tension bolt. You might get it to work without a tensioner for a while; but when riding I can guarantee it's going to fall off the sprocket when you hit rough roads.

This is the same problem people have when they convert an old 10 speed to a fixie. In then end they usually have to add a small tension or get use to stopping and reinstalling the chain.... With the QX100 you will have the added complexity of the boom adjustability which changes the attack angle of the chain which will have an impact on the effectiveness of the drop out. Not sure which tensioner you got but the Surely singulator in push-up mode should work really well for what you doing. I've been long contemplating a N360+Schulmpf on a quest so I've probably consider the issues a few too many time.

If you look Closely on the back wheel you'll see the signulator I had to settle for.

img_2019.jpg DSC04227.jpg
 
ratz

ratz

Wielder of the Rubber Mallet
I forgot to mention; I was also using steel cogs and rings to improve chain retention and power transfer. Once you nail your gearing Surly steel cogs are the bomb on the N360; always run the biggest rear cog that you can to improve efficiency; a 20t or 22t is best if they fit. In the end I think I've written more about the n360 than any single person at BROL so if you have question check and see if it's something I've stubbed my toe on before.
 
DavidJL

DavidJL

Well-Known Member
Just got the tensioner in today. Came from the UK. Had to change the spring to the other hole to make it work with vertical dropout. I have a Contrast brand chain tensioner. I did change out the pulley to a ball bearing pulley I had. Waiting to see how a 39-tooth ring will work. I have been running the boom at the 3-inch position. As I understand it, the chain stay length will change a little bit as boom is changed. Even with the tensioner the chain won't be making a serpentine path through a derailleur. Planning to run a 3-chain waxing rotation since 8-speed chains are fairly cheap. Just hoping the hub will be able to take the torque I can dish out.
 
DavidJL

DavidJL

Well-Known Member
Found I had to take out the spring to get it in push up mode. Thinking about making my own tensioner which would clamp to the chain stay. 39-18 is very close to perfect; there is about an inch of free play on chain. It should be about 3/8 inch. 100 degrees is not enough chain wrap. I ran into a problem with hub. Am not getting all of the range I should.
 
DavidJL

DavidJL

Well-Known Member
Using the FixMeUp! program by Eric House, 42 X 19 provides the next shorter chain stay. 19 tooth is harder to find, but I found a Surly 19 tooth sprocket to use with my 42 tooth chain ring, and I can now do without the tensioner. So at least for my setting of the boom on the Q, about 3 inches, I have a "magic gear". Now the front end looks very clean. The NuVinci hub interface is protected by the dropout.
 
DavidJL

DavidJL

Well-Known Member
I did notice that the chain stay on the Q does indeed change with boom adjustment, giving a tighter chain as boom is let out. This means that if I needed a longer boom adjustment I would return to the slacker 39 X 18 combo. In effect the boom can be used as a chain tensioner. It is much easier to remove the wheel without the tensioner in the way, so I will put up with this inconvenience. For reference on the Q bikes, the shortest useful combo is 42-19, then 39-18, then 42-18, and then 39-17, for longer adjustments. With NuVinci, the chain ring must be at least 1.8 times the cog, but I like to make sure it is at least 2 times. Dang, I was hoping I could make the boom easier to adjust by getting rid of the front derailler...
 
ratz

ratz

Wielder of the Rubber Mallet
DavidJL said:
I did notice that the chain stay on the Q does indeed change with boom adjustment, giving a tighter chain as boom is let out. This means that if I needed a longer boom adjustment I would return to the slacker 39 X 18 combo. In effect the boom can be used as a chain tensioner. It is much easier to remove the wheel without the tensioner in the way, so I will put up with this inconvenience. For reference on the Q bikes, the shortest useful combo is 42-19, then 39-18, then 42-18, and then 39-17, for longer adjustments. With NuVinci, the chain ring must be at least 1.8 times the cog, but I like to make sure it is at least 2 times. Dang, I was hoping I could make the boom easier to adjust by getting rid of the front derailler...
Click to expand...

You can violate 1.8 on a CB you can't generate enough torque on a recumbent to break the hub in the recumbent position; it takes a pedal force that would give you about 1800 watts or more. I ran a 2.1 ration on my CT700 for 3000 miles without any issues. Not that you need to; but maybe that will make you worry less.

Another trick with what you have done; since you have a surley steel cog; add a surley steel chain ring too. You'll get a little bit better power transfer, the rings will last for every and your chains will last longer. Likewise run the biggest cog you can for more chain wrap; you can always make the chain ring smaller to compensate. I think a 22 is the biggest I could run.

I still think you are better off with the tensioner but that's just based on the problem I had; will be curious what you settle on after 1500 miles. Keep up the great work.
 
DavidJL

DavidJL

Well-Known Member
I would like to design a chain tensioner that would clamp to the chain stay about midway between BB and axle, but it's still good to get close to a magic gear anyway. I would also like to see a CVT that is comparable in weight and efficiency to derailleurs, but that animal probably doesn't exist. I do think I will enjoy this setup. The NuVinci will be a knee saver when taking off. Start in low gear and dial up the gearing as you get going. Thanks for the input.
 
McWheels

McWheels

Off the long run
It's a good tensioner. I'm running a S-A 8spd, single chain ring and this tensioner on a V2k. It's also nice that I can get a 25t cog so chain-wrap is good however it's set up. In fact it was the only tensioner that worked with such a large cog at all.
 
DavidJL

DavidJL

Well-Known Member
At this point, I am going to go without tensioner, but have one on hand should I change my mind. The boom adjustment and chain tension work out, at least for me. Amazing how much the chain tension changes with boom adjustment. The singleator looks like a nice tensioner. I have modified the tensioner by taking out the spring and putting in a bronze bushing and bronze washer, and using a small extension spring. This tension did not have a push-up mode. For the NuVinci, my understanding is that 20 teeth is the biggest cog you can use.
 
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