teslanv
1 MW
The spreadsheet doesn't reflect your comments. Can you include the one you are referring to.
Calculating Mid-Drive drive train ratio + nuvinci. How?
- Thread starter omnivore
- Start date
Here's a tensioner design that has been adjusted to maximise chain "wrap" on the sprocket. To get top speed up, increase the tooth-count on the drive sprocket. Up to 60T is possible if it will fit your frame. Make a cardboard cut-out before spending big money on a 52T-60T chainring
Here is where a large chainring might hit the chainstay:
Here is a list of chainring diameters indexed to tooth-counts:
Here is where a large chainring might hit the chainstay:
Here is a list of chainring diameters indexed to tooth-counts:
teslanv
1 MW
Are you using a Nuvinci N171B Autoshift developer's kit with a standard manual shift cable? - Because the the shift ratio is very different from the Autoshifter and the Manual Shifter, and a manual shifter will only give you about 1/4 the gear range of the autoshifter.omnivore said:teslanv said:
that spreadsheet that I posted with my last comment has the correct input numbers. the real world output is for some reason incredibly low.
I'm not saying your spreadsheet is wrong. I'm saying something is wrong on my end. It has so many low gears and basically no high gears. I'm almost done turning the twist shift when I finally feel it kick into a high gear and give some resistance on the pedals. Otherwise I'm riding at very low gears and the motor just SCREAMS and I can't help it at all. I can go from about 3mph to 24mph that is my speed range running through the gears.
As is it beats walking or riding in the heat, but it's more dangerous for me to be going slower than traffic here. I take as many alleys and side streets as possible but our streets (main,side and alley) here are awful and damaged throughout. It's like a vibratory cleaner, I used to have to go through and tighten everything up on my mopeds after every few days of riding or things would start falling off of them.
I may end up just taking it off and putting it onto my singlespeed and going back to simple cassettes on this bike.
teslanv
1 MW
Yes, you can reduce the tooth-count ont he driven sprocket to increase speed.
But based on crank RPM of near 150 and the gearing you should be faster, which is why I question whether the Nuvinci CVT is providing the full Overdrive range is claims. Either that or the crank rpm is inaccurate. Do you have another rear wheel you can install to confirm if it's a problem with the nuvinci? - Don't even need a derailleur. Just wrap the chain on a given sprocket with a known tooth-count and record speed with that gearing.
But based on crank RPM of near 150 and the gearing you should be faster, which is why I question whether the Nuvinci CVT is providing the full Overdrive range is claims. Either that or the crank rpm is inaccurate. Do you have another rear wheel you can install to confirm if it's a problem with the nuvinci? - Don't even need a derailleur. Just wrap the chain on a given sprocket with a known tooth-count and record speed with that gearing.
teslanv
1 MW
Is that real world on the flat, or unloaded bench speed?
teslanv
1 MW
I can only think of a couple possibilities:
Crank speed is not at 150 RPM. - this could be due to voltage drop from a tired battery, or a different kv of motor than is listed, or you may not be able to supply sufficient current to the motor. (Problem with the controller)
Or the Nuvinci drive is not getting full specified range.
Or the Tire diameter is incorrect. (Confirm it is 29" Diameter)
I'd start by trying to verify the unloaded Crank speed (On a stand/bench). You'll probably have to install a speedometer sensor on the rear wheel and confirm wheel size setting on the speed sensor, and then if you confirm chainring teeth & Driven Sprocket teeth, we can calculate the Crank RPM.
Crank speed is not at 150 RPM. - this could be due to voltage drop from a tired battery, or a different kv of motor than is listed, or you may not be able to supply sufficient current to the motor. (Problem with the controller)
Or the Nuvinci drive is not getting full specified range.
Or the Tire diameter is incorrect. (Confirm it is 29" Diameter)
I'd start by trying to verify the unloaded Crank speed (On a stand/bench). You'll probably have to install a speedometer sensor on the rear wheel and confirm wheel size setting on the speed sensor, and then if you confirm chainring teeth & Driven Sprocket teeth, we can calculate the Crank RPM.
omnivore
100 W
- Joined
- Nov 14, 2013
- Messages
- 109
well I've just about given up on this thing. Probably going to put the nuvinci on my single speed and go back to replacing cassette clusters and chains constantly and leave it at that. I'm tired. I've tried a DMR STS Chain Tensioner (chain doesn't fit into the idler/requires dropout lock bolt which is already used by the nuvinci) and Shimano Alfine CT-S500 (tensions downward just like a derailleur so doesn't allow enough teeth to engage, so the chain skips.) I've got this generic tensioner/idler on there now. untentioned, just screwed in and ziptied to the g*****n frame. It likes to get hung somewhere and rip off while I'm riding down the road.
If the tensioner/idler was about half an inch longer it would make all the difference because i could put different size idlers on it in order to tighten the chain a little more and maybe be able to fit a f*****g guide to keep it from slipping left and right. but no, it's not, so every once in a while the chain that only has a few MM of slack left in it will work itself off the sprocket because the teeth of the idler lay on one side of the teeth of the sprocket. so after riding on these terrible roads, it gets loose and leads the chain all the way off the sprocket. Needless to say, AVOID ALL OF THIS MESS COMPLETELY BY HAVING A FRAME WITH HORIZONTAL DROPOUTS!
I honestly am pretty unhappy with the nuvinci, mostly to do with the shifting mechanism. cramming it right next to the chain seems like it was the absolute worst idea. I'm obviously no engineer, but the cradles for the cable tips are actually angled to pretty much interfere with the chain directly. I'm guessing it is to give it room for different sized chainstays? I don't know. I have to put my chain masterlink on backwards to keep the little nubs from catching on it.
The Rohloff avoids this mess by mounting its adjuster to the outside.
I'm pretty much done with all of this, I've sunk almost 3 grand into this thing and I'm just at the end of my rope with ordering stuff that isn't correct. I don't have the space and time to do what I need, I don't have the software/hardware, I don't have the tools. Even if I did I just don't know what I'm doing anyway. I've learned a lot, but it's never enough. Got the kit for sale in the sale section. doesn't look like anyone is biting.
I got a pretty shit welcome to this forum and I have a pretty good feeling I'm not part of this community and it's probably for a reason, Hillhater was just saying what everyone else was thinking I guess. I'm done begging people to help me. Seeing most of my posts with 4-500 views and 6 or 7 responses I guess is just pretty obvious that I don't belong here. Thanks to everyone that was helpful and tried their best to assist me, I probably owe you a few lunches.
Take care ES, it was fun while it lasted i guess. *a single tear*
If the tensioner/idler was about half an inch longer it would make all the difference because i could put different size idlers on it in order to tighten the chain a little more and maybe be able to fit a f*****g guide to keep it from slipping left and right. but no, it's not, so every once in a while the chain that only has a few MM of slack left in it will work itself off the sprocket because the teeth of the idler lay on one side of the teeth of the sprocket. so after riding on these terrible roads, it gets loose and leads the chain all the way off the sprocket. Needless to say, AVOID ALL OF THIS MESS COMPLETELY BY HAVING A FRAME WITH HORIZONTAL DROPOUTS!
I honestly am pretty unhappy with the nuvinci, mostly to do with the shifting mechanism. cramming it right next to the chain seems like it was the absolute worst idea. I'm obviously no engineer, but the cradles for the cable tips are actually angled to pretty much interfere with the chain directly. I'm guessing it is to give it room for different sized chainstays? I don't know. I have to put my chain masterlink on backwards to keep the little nubs from catching on it.
The Rohloff avoids this mess by mounting its adjuster to the outside.
I'm pretty much done with all of this, I've sunk almost 3 grand into this thing and I'm just at the end of my rope with ordering stuff that isn't correct. I don't have the space and time to do what I need, I don't have the software/hardware, I don't have the tools. Even if I did I just don't know what I'm doing anyway. I've learned a lot, but it's never enough. Got the kit for sale in the sale section. doesn't look like anyone is biting.
I got a pretty shit welcome to this forum and I have a pretty good feeling I'm not part of this community and it's probably for a reason, Hillhater was just saying what everyone else was thinking I guess. I'm done begging people to help me. Seeing most of my posts with 4-500 views and 6 or 7 responses I guess is just pretty obvious that I don't belong here. Thanks to everyone that was helpful and tried their best to assist me, I probably owe you a few lunches.
Take care ES, it was fun while it lasted i guess. *a single tear*
Hillhater
100 TW
Pretty poor approach to delete all posts.
What caused that ?
What caused that ?
comradegerry
100 W
A Surly Singleator can help give a good wrap on a chain, has plenty of latteral and tension adjustment, $50 well spent if it works, I love mine.
alsmith
100 kW
omnivore said:
I would think that's not unusual. Look at other posts and you'll find a much lower response rate.
-Do you think most people here have a nuvinci? I bet it's a very small number.
-Some members may have responded but what they were going say was already said. I'd hazard a guess you'd complain about several responses saying the same thing. I put my hand up for this for many posts by many e-s members in the past.
-Many people won't know the answers and are learning new things. I put my hand up for this for many posts by many e-s members in the past. I won't ever buy a nuvinci but I like to learn. I'd hazard a guess many others have a similar interest in things they'll never own.
-Maybe some people are bored and just reading posts to fill in time. Don't worry about them, they are unlikely to continue reading after the first couple of posts. There are better things to do than read something that doesn't interest them.
Remember, it is an open forum so people have the right to read whatever posts they want, whether they have the knowledge to help or not. It is also their choice whether to post a reply if they have knowledge to respond.
If you want a guaranteed response then go pay a professional for their services. A free forum where people give free advice is obviously not what you want and not good enough for you.
Go find your bliss, and good luck.
