Custom Built Fatty - BBSHD & Nuvinci N171 CVP hub.

hsdrggr

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I wanted to build a very clean looking fat bike using the BBSHD & Nuvinci N171 CVP IGH Hub but finding e-bike frames for a road bike is almost impossible. Or expensive for a full suspension fatty frame. So I decided to buy an inexpensive fat e-bike, strip it and rebuild it my way. Wasn’t even sure it would work because the hub is normal axle width 135mm and fat frames are 197mm. So I knew there were going to be chainline issues.
But alas, it can be done.
1. Bend the rear triangle of a 6061 aluminum frame to narrow the dropouts to ~ 135mm width.
2. Remove 5mm from the right side of the bottom bracket face to get the front chainring moved inward to improve the chainline.
3. Obtain a 1.37”x24Tpi freewheel spacer-adapter to move the rear cog over as close to the frame as possible to get the chainline correct.
4. Get the highest offset front chainring as possible. Luna Eclipse chainrings have 24.5mm of offset; the most available. 42T is the smallest with that offset.
5. Die grind the inside of the adapter/spacer to clear the rear hub’s built-in free hub. (Next time I think I would just remove 4-6mm from the outer threads and space the adapter out with freewheel spacers.)

I figured I could sell all the original new parts: 500w hub, wheels, freewheel, derailleur, controller, display, brakes, cranks, bottom bracket, handle bars and stem for about $500.

So all in including the cost of the bike, my cost should be $2000. I think that’s a pretty good deal for a 1500watt mid drive e-bike with a continuously variable planetary transmission hub.

WARNING, This is not a typical DIYer project. If you are a fairly skilled mechanic then go for it.

Here’s the parts list:

Wallke F2 fat tire e-bike. $899
BAFANG BBSHD mid drive. Aliexpress $589
Alex Blizzerk 70 Rims. 365 cycles. $124
80 spokes & nipples Aliexpress $25
Sealed bearing fat Front hub. Aliexpress $24
Nuvinci n171 CVT rear hub. Eco-cycles$100
Rear track cog 3/32” 22t. Amazon $18
Front chainring Luna Eclipse 42t. $100
Origin8 rim strips. 46mm eBay. $18
Bafang gear sensor. Aliexpress. $16
Paul’s - Melvin chain tensioner. Jenson$114
Avid G3 203/180mm rotors. Aliexpress $14
DS07 203mm front caliper bracket. $3
DS02 180mm rear caliper bracket. $3
Derailleur hanger ext. Amazon $10
Eggrider v2 display. Luna Cycles $99
BBSHD stabilizer brkt Luna Cycles$15
KMC e-bike chain. Wiggle.com $22
Ukraine bolt-on Torque plates. eBay $25
Freewheel spacer. E-bike kit.com $70
Jagwire derailleur cable housing. $30
Bottom bracket spacers Amazon. $10
Tektro HD E-350 hyd.brakes Aliexpress$105
PDW front Mud fender. Rambo e-bikes $19
PDW rear Mud fender. Rambo e-bikes $25
Mirror. Amazon $17
90mm Adjustable stem. Amazon $20
Rise Handlebars From Wife’s Aventon Free
Headlight. Aliexpress $6
Front snow shovel basket was a donor part from my wife’s Aventon; she wanted a wicker basket instead. I used RivNuts to attach it to the head tube.

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I like how you used the tensioner to give max engagement on the chain, around the rear cog. That bit of thinking says a lot about attention to detail.

Can the Nuvinci handle the HD's torque?

I have done the thing with both the rear freewheel spacer and bending the rear triangle. Nowhere as much as you did, and my frame was chromoly steel; not alloy (not to mention I was spreading to 197 up from ... 160. Not a size you see often). That much change would be pretty hairy.

Something to consider for a future project if you ever go there again: Many fat frames - particularly the ones meant to handle only 4" tires - have 170mm spacing, so you have a lot less change to effect. For example the Framed Minnesota.

That EbikeKit spacer is the best on the market thanks to the wrench flats. There was only one other, black anodized, I am aware of that has those wrench flats on the outside and I don't think its on the market any more. I have one in a tool tray somewhere waiting for a belt build I'll probably never do.
 
Thanks. I tried a Surly tensioner and it just didn’t have enough tension and less chain wrap and it skipped on a 24t cog under full throttle. So I went to the Paul’s Components “Melvin” tensioner. It’s the Cats Meow. Really good tension and the double pulley allowed me to get that chain wrapped more. I had so much offset that I had to make some shims to add to the Melvin to get enough offset. I contacted them and they are sending me another matching spacer. It’s an expensive tensioner, but it is really robustly made.

Supposedly the Nuvinci will handle 7hp continuous. I saw where another guy was running a 2400watt mid drive through it. But the newer Enviolo CVT hubs have less spheres in the hub and won’t handle that much. But the newer Enviolo HD and Extreme CVT hubs will handle 100nm mid drives in cargo bikes. Pretty impressive.

As for frames; it’s a bear trying to find an e-bike frame with integral battery for a build. Since I already had experience with another Wallke road frame I thought I could bend one without getting stress fractures in the hardened 6061 surface. It was a little hairy bending it but I did it carefully a little at a time so I wouldn’t have to bend it back out which probably would have cracked it. The bike came out super nice. I’m really enjoying it. Once I wear out the CST sneakers I’ll put some real tires on it. I’m liking the CVT feature except it’s impossible to downshift while there is any pedal pressure even with the shift sensor. But up shifting works under pressure just with a little resistance.
I still have another Nuvinci hub, and 4 Enviolo Heavy Duty CVP hubs with Automatiq shifting systems for some future builds. Fun fun.
 
Hah I have used the Surly tensioner on two bikes and it worked great. But to get it to really work right you have to reverse it (the spring inside) so it pushes the chain up versus what it usually does which is go down and out. Maybe you tried this as its still a single-pulley product and has inherently less cog capacity. I used it with IIRC a 16T cog.

I looked around some after posting above and the 170mm fat frames are nowhere near as easy to find as they once were. Looks like its all 190's (QR) and 197's (thru axle). Possibly something to look for is a mid-fat frame. Something meant to take 65mm rims and 3-3.5" tires. I used to build fatties and swore by them but over the years I have found I can get almost all the benefits of fat tires with a 2.5" to 3.5" tire. Provided I stay off dry sand at least. Then there's no substitute for some true fatness.
 
I tried flipping it with the other spring but ran into interference with the chain stay due to cog being so far offset to get a good chain line. So in this situation it had to be a puller vs. pusher type tensioner. I have another hub motor e-bike with 2.35” tires. With the seat post shock it doesn’t bother my back much. But the 4” running 15psi are a little nicer on me. Being an e-bike is nice because your body doesn’t have to overcome the extra rolling resistance. Haha
I’m 61 and had a pretty crazy life, not that I’d trade it for less crazy. I had a ton of fun and didn’t die doing it. But football, dirt bike riding/racing, car racing, and 25 years firefighting left me with, cardiac arrhythmias, asthma from inhalation injuries, 3 neck and spine disc and vertebrae fractures. 3 years ago had 3 vertebrae lumbar fusion. So more cushion on an e-bike and sitting more straight up help me a ton when riding. But I’m never giving up riding. If I have to go to a recumbent next, so be it. I’ve actually been doing some research on them because I know it’s coming.
 
1500 watt, 48 volt system, what is top speed and range?
29mph. Range depends on how you ride it. I don’t ride at 29mph constantly.
I normally ride at 17-18mph. With the controller set to 30amps max I’m right around 25 miles on a the stock 10.4ah battery. With controller set to 20amps max I’m around 30 miles. PAS setting in 4 of 9 on the eggrider display. At 30amps max setting max throttle shows 1400watts being used by the motor, and at 20amp max it shows about 970watts being used by the motor.
Asking about mileage is really a very relative question and will vary based on many factors; PAS settings, throttle settings, amp limits, how the bike is ridden, terrain, wind resistance, etc.
Also a fat tire bike with a BBSHD and an CVT rear hub is fairly heavy and has a lot of rolling resistance. I run the tires only at 15-20psi for comfort and loose dirt stability. I also sit almost straight up so wind resistance is pretty high.
 
I wanted to try a mid-drive motor for my next build, but thought it would be faster than 1500 watt hub motor, which also tops at 30 mph, so I'm not sure I can justify paying more than double.
 
I wanted to try a mid-drive motor for my next build, but thought it would be faster than 1500 watt hub motor, which also tops at 30 mph, so I'm not sure I can justify paying more than double.
You can make them go much faster. But it requires a different controller and higher voltage battery. Controllers like Grin base runner, phase runner and High Voltage BAC855 kit will get your BBSHD the RPMs needed to get speed. They are FOC controllers that utilize field weakening to get the BBSHD rpm’s and power up. These things require a battery that can deliver the amperage. They pull 50+ amps.
Eventually I am probably going to get a Grin baserunner controller because it can be hidden inside an e-bike frame.
 
You can make them go much faster. But it requires a different controller and higher voltage battery. Controllers like Grin base runner, phase runner and High Voltage BAC855 kit will get your BBSHD the RPMs needed to get speed. They are FOC controllers that utilize field weakening to get the BBSHD rpm’s and power up. These things require a battery that can deliver the amperage. They pull 50+ amps.
Eventually I am probably going to get a Grin baserunner controller because it can be hidden inside an e-bike frame.
Right, I want to stay within 48-52 volt system due to overall cost, but for some reason formed a belief that mid-drive is more efficient in top speed.
 
I wanted to build a very clean looking fat bike using the BBSHD & Nuvinci N171 CVT IGH Hub...
This'll be interesting to see how well the Nuvinci can handle the torque. I have over 48K miles on my Rohloff Speedhub with 3 different BaFang mid-drives and am going to send it back to Germany this winter to be rebuilt.
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This'll be interesting to see how well the Nuvinci can handle the torque. I have over 48K miles on my Rohloff Speedhub with 3 different BaFang mid-drives and am going to send it back to Germany this winter to be rebuilt.
According to specs it will handle 7hp continuous, and 130nm instantaneous. Karl Geissling posted an article where he ran a 2400 watt mid drive with this hub with no issues. It’s was produced in 2008 and has since been discontinued for lighter versions. But from what I have researched the N171 still is the king of IGH for handling a lot of power. It is a heavy beast, weighs more than 8 pounds.
 
This'll be interesting to see how well the Nuvinci can handle the torque. I have over 48K miles on my Rohloff Speedhub with 3 different BaFang mid-drives and am going to send it back to Germany this winter to be rebuilt.
BTW, congrats on that kind of mileage. 48K miles, WOW!
 
Really nice!

Interesting what you said about it being impossible to downshift with any pedal pressure, I guess it does shift ok you just have to not have any tension.

I was wondering what your thoughts are about what the gear range is like. It says it is .5 under to 1.75 over What would you say the equivalent rear sprocket size would be in your lowest and highest ranges?

$100 is such a killer deal for a hub like that, I might just have to buy one for a future project.
 
I guess I posted the ratio info in another thread in this forum.

Yes, it will downshift with ease when I don’t pedal.

Since my bike has a 22T rear sprocket; if I’m figuring correctly the range is close to a 11T-38T cassette. 22*0.5=11.5T, 22x1.75=38.5T. I’m running a 42T front chainring.

I did have a 24T rear, but at faster speeds my cadence was too high so I dropped it to 22T. I did not affect the top speed either.
Even a 20T would be fine. I’m really happy with the ratio range and performance. It climbs pretty severe hills without any stress; blows away the hub drive e-bikes I have ridden. Plus it won’t over heat like a hub motor will under heavy load because it is spinning higher rpm’s which puts less stress on the motor. It will actually wheelie right out from under you if you nail the throttle at a stop with the hub in the lowest ratio setting.

If you want one of those Nuvinci N171 CVP hubs you better order soon. About a month ago David at EcoCycles told me that they don’t have many left. They are selling them on eBay. He only has the black 32H version left, so you will need 32 hole rims to lace them into. The PDF Nuvinci N171 tech manual actually has spoke lengths listed in it for common wheel sizes. Or if you want an exact calculation for a specific rim you can enter hub and rim data into the spoke calculator at Grin’s website. I used the grin calculator to figure my spoke lengths. The only online supplier for custom length spokes that I could find in the USA was Cartersville Cycle's in Georgia, USA. But the 12g spokes that they made for me were not threaded correctly. The threading die they used did not press deep enough into the spoke to push threads up that were deep enough, so when I started tensioning and trueing the wheels the nipples stripped off the spike threads. So I ordered them through a vendor on Aliexpress and they were perfect and came with nipples. The ones from cartersville did not come with nipples. The price was similar from both entities. So the ones from China were actually a better deal since they came with brass nipples included. Here’s the vender I used: ZEMAKE Store
BTW, max spoke diameter for the hub is for 13g. I drilled out and chamfered the holes in the hub and rim to accommodate 12g. I would recommend just sticking with 13g stainless spokes they are plenty strong enough. On my 26” rims I did one cross for the rear wheel with all spoke heads on the same side of the hub. That is the hub mfg. recommendation also. I ran all the spoke heads on the outside of the hub flange since the rim had zero offset. If you need offset then I’d recommend running the spoke heads inside on the side that the rim is offset to.
 
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Reposted from another thread:

Since someone inquired about the hub in my fat bike build, referencing the Nuvinci N171 CVP hub’s ability to climb hills. I’ll post it’s ratio specs. It has a 350% ratio range (0.5 Under-Drive to 1.75 Over-Drive) So on my bike it’s similar to a 11-39 cassette. I’m running a 42T front chainring on the BBSHD and 22T rear track cog. It climb’s serious grades extremely well. It’s low end ratio is actually a little too low in this configuration for pedaling; the cadence is too fast for me to even match it. However where it shines is in its torque/climbing ability under throttle. I made this bike as a fun bike, for beach, off road hilly terrain and for general goofing around. It only has a 10.4ah battery because I don’t really care about distance. I have another e-bike for that. However I have found that I really like it for short trips on the road with my wife on weekend jaunts to restaurants, concerts, and to the beach. These rides are about 25 miles max round trip and battery is more than capable for that.
 
I wanted to build a very clean looking fat bike using the BBSHD & Nuvinci N171 CVP IGH Hub but finding frames for a normal road bike is almost impossible. Or expensive for a full suspension fatty frame. So I decided to buy an inexpensive fat e-bike, strip it and rebuild it my way. Wasn’t even sure it would work because the hub is normal axle width 135mm and fat frames are 197mm. So I knew there were going to be chainline issues.
But alas, it can be done.
1. Bend the rear triangle of a 6061 aluminum frame to narrow the dropouts to ~ 135mm width.
2. Remove 5mm from the right side of the bottom bracket face.
3. Find an adapter to space a rear cog over as close to the frame as possible.
4. Get the highest offset front chainring as possible.
5. Machine inside of adapter/spacer to clear the rear hub’s built-in free hub. (Next time I think I would just remove 4-6mm from the outer threads and space the adapter out with freewheel spacers.)

I figured I could sell all the original new parts: 500w hub, wheels, freewheel, derailleur, controller, display, brakes, cranks, bottom bracket, handle bars and stem for about $500.

So all in including the cost of the bike, my cost should be $2000. I think that’s a pretty good deal for a 1500watt mid drive e-bike with a continuously variable transmission hub.

WARNING, This is not a typical DIYer project. If you are a fairly skilled mechanic then go for it.

Here’s the parts list:

Wallke F2 fat tire e-bike. $899
BAFANG BBSHD mid drive. Aliexpress $589
Alex Blizzerk 70 Rims. 365 cycles. $124
80 spokes & nipples Aliexpress $25
Sealed bearing fat Front hub. Aliexpress $24
Nuvinci n171 CVT rear hub. Eco-cycles$100
Rear track cog 3/32” 22t. Amazon $18
Front chainring Luna Eclipse 42t. $100
Origin8 rim strips. 46mm eBay. $18
Bafang gear sensor. Aliexpress. $16
Paul’s - Melvin chain tensioner. Jenson$114
Avid G3 203/180mm rotors. Aliexpress $14
DS07 203mm front caliper bracket. $3
DS02 180mm rear caliper bracket. $3
Derailleur hanger ext. Amazon $10
Eggrider v2 display. Luna Cycles $99
BBSHD stabilizer brkt Luna Cycles$15
KMC e-bike chain. Wiggle.com $22
Ukraine bolt-in Torque plates. eBay $25
Freewheel spacer. E-bike kit.com $70
Jagwire derailleur cable housing. $30
Bottom bracket spacers Amazon. $10
Tektro HD E-350 hyd.brakes Aliexpress$105
PDW front Mud fender. Rambo e-bikes $19
PDW rear Mud fender. Rambo e-bikes $25
Mirror. Amazon $17
90mm Adjustable stem. Amazon $20
Rise Handlebars From Wife’s Aventon Free
Headlight. Aliexpress $6

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Lots of work but looks like a very nice ride.
 
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According to specs...
Rohloff designed and built the Speedhub to handle more torque than two human athletes generate on a tandem bike. I don't understand the science since there are so many variables in bike drive trains now from runners to fat bikes. I do know that the "improper application" of 1+ h.p. and potentially 160Nm can pull chains apart and twist a high-quality tensioner off the bike.

"The NuVinci CVT ($599.00) replaces derailleurs and other internally geared hubs, and provides a gear ratio range of about 350%, similar to that on bicycles with 8- or 9-speed hub gears, or with double chain rings (most racing or fast road bicycles)."

"The Rohloff SPEEDHUB 500/14 ($1500.00) has a 526% range of gears, which means gear #14 is 5.26 times greater than gear #1. The 14 gears are evenly spaced out over this range in 13.6% increases. Through the choice of chainring and sprocket in use, the Rohloff SPEEDHUB 500/14 can be tuned for the specific riding purpose."


It's not just the IGH that takes a beating when riding an ebike. Riding much further and in worse riding conditions takes a toll on the whole drive train. Carrying and pulling heavy loads over long distances and grades tests durability pretty quickly. I've learned that a chain tool or breaker/splitter tool isn't the best way to go anymore. Using link pliers and the speed link is much better with today's bike chains... most especially with mid-drive motors. My Speedhub has received yearly maintenance and twice-yearly oil changes and is still operating fine, not like new, but after 7+ years neither am I. If you ride like I do, time'll tell.


Stay safe.
 
Yeah I stayed old school for a long time but eventually opened my eyes insofar as the use of master links are concerned. Those little round metal rings that end up on the chainbreaker's pin (after you hear and feel that little 'pop') are the mushroom reinforcement that was formerly on the end of the pin, that is now gone. Their removal creates a weak spot that means that link is more likely to separate.

Rohloffs are 'only' rated to 130 Nm. It is rare for a BBSHD's 160 Nm to break them, but it happens. In theory the Kindernay, which is rated for 160 Nm, is up to the task, but apparently thats conditional as they have been known to break as well; possibly due to motor settings that are too cavalier in how sharply they ramp up power.

I've always coveted a Rohloff, but have never been up for the added expense of it plus a Gates belt after I've gone and built out everything else to how I want it. Part of that is knowing derailleurs so well and IGH's only barely.
 
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