Hub "Mid Drive" Build

Heya all, I decided I should start a new thread since I am going a new direction for the drive type of my cargo/touring bike. Not much to show, I have all the parts and pieces, just finding the best way to put them all together.

Here is the bike:



It has the Nuvinci CVPT hub in back, soon to have the second fixed cog for the hub motor drive chain.

Here is the motor, Amped Bikes 9 x 7 DD Hub motor.

This is a rear hub motor, and it has much wider spacing that I need, so I am going to so some "shade tree mechanic" machining, starting with an angle grinder, finishing with a file.



Here is the result:



Here is the carcass of the old exercise bike that will be donating it's drop-outs and probably that entire horizontal square tube (or at least enough of it to make a good strong "C" channel) to mount on top of my rear rack.





The only question now is weather to take the axle (assuming it's not too hard to get out) to the local machinist to get threads down further, or use some kind of bushing to make up the difference between where the threads end and the new flats of the axle go.

I'm really pleased with how well my "shade tree" machining has come out, it's really even and was just eye-balled, but my caliper shows nearly identical spacing between the end of the shaft and the new shoulders on the axle (can't see day-light in the difference between the two shoulders with my calipers. 8) )

So you decided you wanted regen braking after all? What are you going to do about the mountains? Ready to cut me a deal on that heavy Nuvinci yet, since you don't need it any more unless there's another motor in the plan?

John in CR said:

So you decided you wanted regen braking after all? What are you going to do about the mountains? Ready to cut me a deal on that heavy Nuvinci yet, since you don't need it any more unless there's another motor in the plan?

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Yes, your point about saving the brakes on long descents by using regen made a lot of sense, and no the Nuvinci isn't being deleted, it is the Linchpin of this builld!

The reason for the "Hub Drive" title is because it's not a typical "mid drive" since the hub motor will be running a chain to the Nuvinci.

Dogman also made a good point about having a lock ring to keep the 14T cog tight on the hub motor under regen, and I have just the thing! An old BB lock ring threads right on. 8)

It will make more sense once you see it coming together, but needless to say, once I have this put together, I will have a 1.57 to 1 single stage reduction from the hub motor (no wheel just the motor) mounted above the Nuvinci, and that will give me some serious low gears!

Oh, that reminds me, I forgot to show off my other find! here are some pics of the gears:

Here you see the new 74 BCD adapter (new to me, used from City Bikes in Portland) on the left that allows incredibly low chain rings to be mounted! I think it uses some form of freewheel cogs, but currently it has a 21T chain ring (this is where you mount the lowest chain ring on a typical MTB 3 chain ring crank) so I have some way to pedal up-hill with minimal effort in-case the electrics have trouble.

On the right you see the Surly 22T Track Sprocket, New Dicta freewheel and some no-name 14T track sprocket. These all bolt onto standard freewheel threads!



Here are some close-ups for the ultra low chain ring adapter. Anyone recognize this four point drive for the removable sprocket?

why not just a front hub? less is better.simple.ive been watching the builds and you keep me goin, ow boy. ,but very entertaining i must say.

beast775 said:

why not just a front hub? less is better.simple.ive been watching the builds and you keep me goin, ow boy. ,but very entertaining i must say.

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Ever try to keep a hub motor happy chugging up a hill with 350lbs? I'm taking a different tact on the stoke monkey idea. They use the BB as transmission to make a cargo bike capable of climbing San Fransisco's nastiest hills.

http://clevercycles.com/products/stokemonkey/

We’ve managed 480 pounds gross up the steepest block in San Francisco (31.5% grade). This extreme torque capability distinguishes Stokemonkey from electric bike products not designed for cargo applications.

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I'm taking a similar design, but using the Nuvinci Hub as my transmission, and instead of using an Extra-Cycle cargo bike build, I am using a standard Tidal Force frame with pannier bags.

If I was just building a commuter that didn't need to haul a ton of weight, I would just use a hub motor as normal, probably an 9c 8 x 8 with 60 - 70V.

Where I live, hills are a big concern, and when I take my trip here soon (as soon as I have all this done and a little cash saved up for emergencies on the road) across the US, west coast to east coast, I will be climbing any number of steep grades.

LI-ghtcycle,

Sorry to burst your bubble, but the Nuvinci can't do regen. The Nuvinci sprocket is a fixed gear, so it has to coast instead of drive the motor for electromotive braking. Otherwise it would force you to pedal as if it was a fixie with a CVT. If the hub required a freewheel sprocket in normal use, then yes it would drive the hubbie for regen if both had a fixed gear, but it doesn't, so it has to coast. I tried asking you about this in your other thread.

Regen won't net you much on a cross country trip, though getting some back after cresting a peak would have been nice. It would have been extra nice to have no brake fade concerns, and super nice to potentially not have to fiddle with brake maintenance the entire trip. Adjusting mechanical disc calipers drove me crazy with adjusting them almost daily. I loved my hydros for that at first, but then I got tired of having to replace brake pads every 4-6 weeks. Now with regen I rarely have do any brake maintenance at all, and I get a bit of juice back as an added bonus.

I thought you were narrowing the flats to fit the front dropouts.

John

No regen is no loss really. But you might carry some spare brake pads or calipers in the mts.

John in CR said:

LI-ghtcycle,

Sorry to burst your bubble, but the Nuvinci can't do regen. The Nuvinci sprocket is a fixed gear, so it has to coast instead of drive the motor for electromotive braking. Otherwise it would force you to pedal as if it was a fixie with a CVT. If the hub required a freewheel sprocket in normal use, then yes it would drive the hubbie for regen if both had a fixed gear, but it doesn't, so it has to coast. I tried asking you about this in your other thread.

Regen won't net you much on a cross country trip, though getting some back after cresting a peak would have been nice. It would have been extra nice to have no brake fade concerns, and super nice to potentially not have to fiddle with brake maintenance the entire trip. Adjusting mechanical disc calipers drove me crazy with adjusting them almost daily. I loved my hydros for that at first, but then I got tired of having to replace brake pads every 4-6 weeks. Now with regen I rarely have do any brake maintenance at all, and I get a bit of juice back as an added bonus.

I thought you were narrowing the flats to fit the front dropouts.

John

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Au contraire, Mon frere! You are confusing my older N171B with the new N360 model which does have a fixed gear. :wink:

Mine has a freewheel adapter so that it won't act as a fixie just as you described.

The motor driven chain will have fixed sprockets on both ends, and the pedal chain will have a freewheel.

Have to help the nephew repair the bunny cage, though it gives me a good excuse to goto the hardware store for a spacer for the axle!

(Dad would have me spend a few days digging through the garage for the old rusty hinges that he has stashed somewhere, but after looking an hour where they "should be" I am off to buy some brass ones that won't rust solid like the ones that are on it now .. guess who installed those ... :lol: )

You know to save confusion, I should probably start calling it my "Old-Vinci"

If the wheel will drive the gear when the wheel rolls forward then you are good to go for regen, a lucky break for you because I consider no coasting a bit of a design snafu that they since corrected. Good think we jumped through these extra discussion hoops, because I definitely want the option, fixed or FW, so I need to buy an old version.

Keep in mind that regen will try to unscrew the hub's fixed gear just like the motor torque during electric assist will try to screw the fixed gear on the hubbie.

Now hurry up and get the Nuvinci proven with a cross country ride using a hubbie mid drive. Actually I'm most interested in power consumption at 20mph on flat ground during your testing, both in direct drive as well as with the motor at full throttle and decreasing the gearing with the oldvinci until you get back down to 20mph.

John in CR said:

If the wheel will drive the gear when the wheel rolls forward then you are good to go for regen, a lucky break for you because I consider no coasting a bit of a design snafu that they since corrected. Good think we jumped through these extra discussion hoops, because I definitely want the option, fixed or FW, so I need to buy an old version.

Keep in mind that regen will try to unscrew the hub's fixed gear just like the motor torque during electric assist will try to screw the fixed gear on the hubbie.

Now hurry up and get the Nuvinci proven with a cross country ride using a hubbie mid drive. Actually I'm most interested in power consumption at 20mph on flat ground during your testing, both in direct drive as well as with the motor at full throttle and decreasing the gearing with the oldvinci until you get back down to 20mph.

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You bet! Just finished the bunny cage repair, so now I can get back to work!

Good point again on the regen wanting to unscrew the fixed sprockets, I have a lock ring from an old BB that works just great for that.

Another reason to use the "Old-Vinci" is that they have the cabling out-board of the frame, leaving plenty of room for the second chain drive, the new one puts the cabling between the hub and the frame, making things pretty tight. I'm sure you could still squeeze in a second chain in there, but like you say, options are good, and you can get the old ones cheaper, just know that Fallbrook no longer officially supports the old ones, so parts are eventually going to become scarce.

I'll have some pics of the fixed sprocket behind the freewheel and the hub motor in the exercise bike's drop-outs. I had to cut out the basket pannier from the old fairing, but I didn't want to completely dismantle it, so I took longer doing it in a way that keeps it mainly intact. I will be using some portions of the old fairing to build up the new (totally new design, but the inside will have similar structure) and hold my alarm and solar panels.

Now back to work! (at least until dinner in about 1 hr .. )

DOH! Well, back to the drawing board on a couple things, the cogs that I have are designed to take up more threads than I anticipated, and my old basket pannier isn't going to cut it for holding the exercise bike piece with the drop outs, in fact, since I am using disc brakes, the basket panniers themselves aren't going to work, so now I'm going to look at some disc compatible rear racks, and trade in the 14T & 22T cogs for a 17T and some 1/8 single speed chain.

I've ordered the custom sprocket/freewheel adapter combo from Staton:

http://www.staton-inc.com/store/pro...0H_sprocket_and_freewheel_adaptor-543-38.html



It uses a 27T 1/8 single speed chain sprocket for the solid cog on the Nuvinci hub side, so I will be using a 17T on the hub motor to make the same gearing as before, and this will be easier to source and easier on the chain as well as quieter I imagine than the 14T cog. Good thing that City Bikes will give me full value on the used stuff to trade back for more used/new stuff. That means I will have one custom piece, but at least it's sort of "off the shelf" from Staton Inc. I'll buy a second one to take with me on the big trip.



In the meantime, I might do like you mentioned John, and put the motor on the front forks so I can have a motor to use, I'll have to figure out some torque arms to be safe, never used a hub motor on the front for my personal bike, and I know that the Surly big dummy forks are probably strong enough to go with out them, but better to be safe.

New things to buy! :lol:

Gotta love it, when ever you make something custom, there are always things you don't expect.

Here is my new dilemma: the Nuvinci has more over-drive than under-drive, therefore to get really low gearing, you need a tiny, tiny chain-ring up front, or a large freewheel in the back, or both.

I'm trying to keep things as close to standard off the shelf parts as I can, so I tested out the 21T mini-chain ring that I got, and it's pretty good, gets me pretty low gearing for climbing a 10 - 12% grade, however, I know that I can hit something much worse (30%+) on a trip coast to coast, so I'm going to need more options.

I have been using a pretty standard 3 chain ring shimanno 5 bolt crank that you will find on MTB and touring bikes from the 80's and 90's, and I am thinking maybe the newer 4 bolt MTB cranks will have a better range in small chain rings? I'm thinking something that would let me go as low as 18T?

Time to look up on Sheldon Brown I guess!

Well, I got my standard 4 bolt MTB crank with 22T granny gear, and I lucked out finding it in the form of a used FSA crank, now I am going to start opening up the square tubing of the old exercise bike and mounting it temporarily onto a rear rack that I have just to see how this needs to go before having a custom rack built.

Should have something to show in the next couple days!

Ok, some pics, I have been obsessing on small stuff (just noticed dirt had worked it's way into my tail light and couldn't leave it until I got it all out! ) so it's taking longer, I hate to do anything half-way even in a mock-up or prototype, so I am going to paint the rear rack drop-outs before installing it.

Here are some pics so far:







I needed a large spacer for the rear rack to clear the disc brake, so I had 5 washers in a row, and then it occurred to me to put shrink wrap on the washers, and I took on crappy pic, then my camera died! :lol:

So here is the best pic I have atm, I will get a better one soon as the camera is charged.

Superglue works good for washer stacks too!
otherDoc

Ahh, yeah I can see how that would! I really lucked out with the shrink, didn't even think about this, but I had enough on each side that it covered the ends too so no worries on painted surfaces.

I got the drop-outs all painted, built some torque plates for a friend yesterday, so put this job on the shelf for a bit, but I am back to work today, more pics coming soon.

More pics, kinda boring, but more just the same:









I have hit a bit of a snag, it looks like the chain line won't clear the exercise bike's drop-outs as easy as I thought, will have to make some adjustments.

Turns out it might not be that hard after all, I just have to run the chain at an angle instead of straight down, and it should clear things fine. The only concern now is if the rack that I am using for the mock-up might interfere with the chain line.







I will try and test fit the mock-up tonight, but my energy level is pretty low, might have over-done it last night, so today I am having to take it easy. (this is particularly hard for me since I am normally high-energy and able to do much more!)

Made some progress this week, had a visit with the neighbor to get some quick welds made for my proto-type:





This eliminated the problem caused by the diagonal drop-out angle and wasn't too hard to do, as a bonus, this made the distance from the mid drive drop-outs to the Nuvinci shorter too.





With these drop-outs, I don't need to worry about chain tension since I can move the drive up and down to get ideal tension.



Had to extend the chain about 8 links beyond a standard length single speed chain, but that will change in the final version where the drive hub will be just beyond the rear wheel going towards the back, freeing up the top of the rack for cargo.





There is some concern around the derailleur, tight clearances, might have to do something different if it becomes an issue.

Just in time for the snow! :lol: :lol:

Actually here that means cold rain with snow, and soon will be black ice. Hopefully we get some better weather soon, hate to test this in sleet/black ice!

Just nit picking here, maybe you are slim? But it looks to me like the hub rotating is going to rub a hole in your pants.

Mabye a fender of some kind on the finished bike?

Yes, this is just for no-load testing, I have an old fender in mind to prevent that and a coat getting caught.

Hey LI-ghtcycle! That is a nice piece of work. I do have a question about having 13 lbs of rotating mass up that high. Have U noticed any problems with handling or gyroscopic reaction?
otherDoc

docnjoj said:

Hey LI-ghtcycle! That is a nice piece of work. I do have a question about having 13 lbs of rotating mass up that high. Have U noticed any problems with handling or gyroscopic reaction?
otherDoc

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Thanks!

Unfortunately I won't have a good answer for probably a few days, today was looking encouraging, but now the sleet/hail is coming down and it's just above freezing, so soon it will be icy.

I got to the garage and replaced the front wheel, and need to solder the phase wire connectors (combining the 9x7 with a different controller, same halls, different bullet connectors for the phase wires) but I'm not very energetic today, so might be a little bit before I get even some no-load testing in.

I am curious to see how this will look when it's all done. Do you have a drawing of how it will look after the mechanicals are done and cargo pods are attached?

Was there a reason not to put the hub motor in the triangle? I would have thought that a natural place to put it.

No one has tried exactly this arrangement, I'm very interested to hear your findings after the first ride!

Katou