I have a vision.

[bringageek]

My vision is that of an almost entirely custom made electric bike build. And many of the stock parts will be sort of "off label" applications. The frame is a tasteful combination of a tube or two here and CNC'd forms there. I really should put together a proper 3d cad of the concept sometime soon.

That aside, I'd like to describe what my plan is for the drive train system. Essentially, I would appreciate it if you fine folks would let me know whether or not I'm completely off my rocker. Any other constructive feedback or suggestions is also welcome!



Here goes.

I plan to use the Nine Continent 2805 Front Hub Motor with the Disc Brake Pattern essentially not in a rim at all but as a mid-drive between the crank and the rear wheel. Said rear wheel will be housing a Sturmey-Archer 8 Internally Geared Hub that features a wide range gear ratio and logically positioned gears (the 1st gear is actually direct drive, so a smaller crank can be used). Powered up by a 48V Lithium battery and the 25A Infineon controller.

Oh… and all the components are belt driven instead of standard chain.



Now you're probably wondering how in my head that all is supposed to work… or even why someone would even consider it. But here's how and why.




My plan is to run with the ready to go, off the shelf 48V and 25A controller. I want to avoid the tricky and rather expensive business of using high voltage batteries (60V, 72V, 84V) and special high 40A controllers and overheating, and battery discharge ratings et cetera et cetera.

But I still this bike to be able seriously haul ass if desired. From what I gather external DC (non hub) motors can tear up pavement at the with crappy SLA 36v and 48v batteries -- especially since they can take advantage of the bicycles rear wheel gears. The downside I believe is that most of them are brushed motors, that they gobble power like a columbian dictator, so getting that high speed means sacrificing overall range, and the motor's lifespan isn't all that good. After a couple to many glasses of scotch a few weeks back when most of the lights in my brain were dim I though of using the hub motor in place of the external brushed motor. Get the best of both worlds.


I decided to select the NC 2805 Front hub motor for a couple of reasons. From what I understand the 2805 is the fastest of the NC hub motors… Essentially able to produce the highest RPM per volt. And I chose the Front Hub with disc brake mount because I plan to flip it around so that the disc bolt mount is on the right hand side of the bike along with all crank and rear hub. And run it in reverse via the controller. I'll have a simple adaptor collar machined up for me that I slide over the axle, attach to that mount that has a standard 1 3/8" diameter with 24TPI threads. The front crank will link up to a freewheeling cog and right beside it will be a single fixed cog that then links with the single cog attached to the 8speed internal rear hub.



This way, when I peddle, it will turn the hub motor which will of course turn the rear wheel hub. When I whack back on the throttle the motor will turn the back wheel, but not the front peddles thanks to the freewheel cog on the motor.

And because the hub motor is connected to the rear 8spd I should be able get both a good off the line acceleration as well as a pretty decent top speed.

And if I want to boost the overall range I can choose a 48V pack with more amp hours.




(And if for some reason I have the desire to go from what should be a pretty fast ride to the range of stupidly fast, I still have the option of doing all that other high voltage stuff that is normally done to get a boost out of hub motor bikes).




And lastly… the decision to go with belt drive is… mostly because I can. The 5mm GT and HTD belt/pulleys are not only extremely efficient, they're easy to setup, much quieter than chain, but they should be pretty long lasting and will require less cleaning and lubing and maintenance. Plus they look freaking cool. And thanks to the fact the Sturmey Archer Internal hub has been overhauled such that the 1st gear is direct drive, I can get away with using belt pulleys that are smaller than chain sprockets. And I can fine tune the drive system with different pulley combinations. Tooth counts range from like 11 to 95 or something like that. And those are just standard stock sizes.






I just read over all that. Seems a bit like a rambling monologue…. Geezzz… I'm long winded.


So… what's the verdict? Brilliant or Basket Case?

 

[aaronski]

sounds like a stoke monkey.

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

 

[Miles]

And lastly… the decision to go with belt drive is… mostly because I can. The 5mm GT and HTD belt/pulleys are not only extremely efficient, they're easy to setup, much quieter than chain, but they should be pretty long lasting and will require less cleaning and lubing and maintenance. Plus they look freaking cool. And thanks to the fact the Sturmey Archer Internal hub has been overhauled such that the 1st gear is direct drive, I can get away with using belt pulleys that are smaller than chain sprockets. And I can fine tune the drive system with different pulley combinations. Tooth counts range from like 11 to 95 or something like that. And those are just standard stock sizes.

I suggest you do further research on this aspect of your design. 5M GT2/3 belts will definitely not handle the torque.........

 

[dogman dan]

Doesn't sound so off your rocker to me. But you will want to amp up, even if you don't volt up. So I predict a bigger controller in your future. Perfect sense to perfect the drive train using the small controller though.

No matter how you gear it, you will hit the wind wall at 30 mph on 1000 watts. So even if you don't increase speed by increasing volts, you will requrire the same wattage we use when we go 40 mph. Gearing is not going to magicly make your watts more. You can of course, eventually reach higher speeds by gearing up, and do what is possible to reduce drag.

 

[FMB42]

That's a pretty serious challenge you have there bringageek. But then again, we'd all still be living in caves if people didn't strive to achieve their ideas...

I think you're just about ready to start taking it to the CAD stage at this point.

BTW, have you worked out your cost estimates and, if so, are these costs within your proposed budget?

Note: you should, imo, add an additional 33% to your over-all budget at this stage of your build.

 

[Rassy]

Aaronski said:

sounds like a stoke monkey.

The Stokemonkey guys don't like us using their trademark name for our DIY projects. But yeah, I described mine that way when I first built it. I think it's a real feather in their cap that everyone knows that they developed the original mid-drive hub motor system.

See LI-ghtcycle's thread of his visit with Stokemonkey:

http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=25747&p=373521&sid=85fab8dd72e5dfab11d45fda0ea97759#p373521

Anyway, if you can get all the belts and freewheels working together properly it should work great. One of my challenges was getting the motor speed and pedaling cadence in sync ahead of the 8 speed IGH. It's about perfect now and I really like it.

 

[Drunkskunk]

Sounds like a Plan.

I see some obsticles though. First being the Sturmey-Archer 8 speed. I love archers, but the 8 speed uses a 1:1 first gear, and all higher gears are over drive. that makes it less efficent and les able to handle the torque of a motor than any other brand 7 or 8 speed. Idealy, you want your 1:1 gear to be mid range, with over and under drives for the top and bottom, like Nexus, Rohloff, NuVenture and SRAM do it. the 3 and 5 speed Sturmey archers do it that way as well, and would be fine.

The other is with your chain routing. running from crank to motor to rear wheel is a good idea. but there are already Freewheel cranks, so you could avoid the expense of creating a new part for the motor by using the crank as your freewheel.

As for the belt drive, its not sutable. They are less efficent by 5 to 10% than a chain, far weaker, and while possably technicaly more quiet than a chain, a chain shouldn't make any noise you can hear. If you'r chain is noisy, it needs lube and adjustment.

your top speed will be goverend by the watts available. being geared will give you a better torque range up to top speed, but ultimatly, your speed is limited by the watts available, and since you're on a geared system, losing around 5% efficancy in the chain, and another 5 to 10% in a geared hub, you're top speed will be 10-15% lower than it would have been with a direct drive.

If top speed is your goal, chain driveing a hub motor isn't the way to get there. But for efficant extraction of torque at lower speeds, its a good plan.

 

[John in CR]

"Seriously haul ass" is not going to happen with 48V25A, unless your definition is drastically different from mine. Since you're talking about performance, that is likely to be an ongoing chase for you. I would suggest getting a controller that will grow with you, and your out of wheel use gives you plenty of flexibility. I'd suggest a programmable 12fet with 4110 mosfets that is set up to handle 36-84v.

Also, if you're not squeezed for space in terms of width, I'd suggest a rear disc brake ready motor. Then you have more axle to work with in terms of mounting, along with flexibility in the future. eg maybe later you want to use the motor differently where the threaded freewheel attachment point is useful.

 

[bringageek]

First off, thanks for all the feedback thus far!

As for my budget... I'm not entirely sure yet. Because I haven't entirely settled on the drive train setup and battery mounting I haven't begun CADing this sucker out. And until I do that I can't exactly a ballpark estimate on the machining cost. If the total cost including stock bike components, drive train and battery, and frame fabrication with finishing was near $2500 I would be pretty pleased. I could probably even comfortable with $3000 being the end cost. And I could live with $3500 if it looked and functioned exactly as I imagine and hope.

I'm too poor to buy cheap shit. I'll blow close to two weeks pay on a pair of dress boots because I know that if properly cared, could in fact last me the rest of my life. But on the flip side, when it comes to thinks such as my power tools. Sure, a Delta Unisaw (about $4500) would be almost orgasmic to own, for what I would use to do would be wasteful. Heck... Even the BOSCH with that gravity rise stand (About $850) would never be fully used to it's potential even though I could appreciate it. I settled on the Ridgid Compact 15A portable. My needs will only push it to the edges of the limits of it's abilities rarely, there are things that I do with it that a cheaper similar model or bargain basement JobMate or even a MasterCraft would fall short o meeting my needs.



It's been a long day and I'm starting to doze off, so I'll try and outline what my expectations are when it comes to the drive train's performance and hopefully you can help me get there If I were stopped a the end of a parking lot driveway, I look both ways, and then without pedaling if I desired, as I start to twist the throtte I start to move forward. After about 150 feet I could be up to about 12 to 15km/hr, kind of a little half twisting. Then I essentially twist from half to full throttle and the works it's way up to full speed (32 or 35km/hr) over let's say the next 150 to 200 feet or so. I want to feel like I'm in control of the rate of acceleration. In the event that I did decide to pretty much go full twist right off the line the bike could get up to the full 32km/h like it was in a hurry to dos... perhaps a little over a little less distace than the leisurely daily cruise.

Now for the haul ass part... I want to have a switch, or a button, or a small lever. Say I'm moving along at a decent pace over a generally level ground with the throttle at full, I let off the throttle for a second the bike continues to coast, I throw the switch, and bring the throttle all the way back up to full again in a second or so and the bike starts to pick up speed, a bit as if I was starting to gain some momentum down a mild hill. Essentially with that switch engaged the top speed over a generally level road is somewhere around 50 or 60 km/hr. The kind of speed that would like turn a few heads of people walking down the sidewalk when they just realized that it was bike that just whizzed by.,,, Probably a thrill enough for me that I deiced to lift the goggles off the front helmet and put them on before I switch it up. I think 50... 60 is likely fast enough to put grin on my face and maybe even a let out a Woooo! and raise the pulse rate a little bit. The idea is that it's not something I really plan on doing all the time. More for when I'm in the mood for it. Or maybe when I know there is a restaurant patio half a klick up the road that is probably full of people right now... let's show off a bit.




I'm going to crawl into the fart sack now and I'll be back tomorrow with a few replies and a probably a buttload of question.



Woooo!

 

[Drunkskunk]

What your expectations are, are very reasonable. In fact, not very hard to achieve much simpler than you plan for.

A basic 9X7 9c hub motor can accelerate you to 30kph (18 mph) in 300 feet, roughly, and should top out at 35kph (22 mph) on just a 36volt battery (lithium) and a mild 20Ah controller. By running 2 batteries, and having a switch for parallel to series, and a controller capable of 30 to 40 amps, you could fulfill your wish of having a switch for high performance, and given wind resistance, you should top out around 60 kph (35 mph), or more.

No gearing necessary, thats just as a straight drive hub motor. Using gears in a case like that would only hurt performance.

Gears are for hills, like the alps, or carrying 2 fat tourist on the back of a pedicab. for normal riding, a hub motor has more than enough torque, and since electric motors make full torque zero RPM, just compounding gears only has limited use for efficiency reasons. and that efficiency evaporates at cruising speed were extra pieces in the drive train zap the efficiency.




edit:added mph conversions for the kph. My bad, this should make more sense

 

[gtadmin]

... I plan to use the Nine Continent 2805 Front Hub Motor with the Disc Brake Pattern essentially not in a rim at all but as a mid-drive between the crank and the rear wheel. Said rear wheel will be housing a Sturmey-Archer 8 Internally Geared Hub that features a wide range gear ratio and logically positioned gears (the 1st gear is actually direct drive, so a smaller crank can be used). Powered up by a 48V Lithium battery and the 25A Infineon controller.
...

My plan is to run with the ready to go, off the shelf 48V and 25A controller
...

I decided to select the NC 2805 Front hub motor for a couple of reasons. From what I understand the 2805 is the fastest of the NC hub motors… Essentially able to produce the highest RPM per volt. And I chose the Front Hub with disc brake mount because I plan to flip it around so that the disc bolt mount is on the right hand side of the bike along with all crank and rear hub. And run it in reverse via the controller. I'll have a simple adaptor collar machined up for me that I slide over the axle, attach to that mount that has a standard 1 3/8" diameter with 24TPI threads. The front crank will link up to a freewheeling cog and right beside it will be a single fixed cog that then links with the single cog attached to the 8speed internal rear hub.

This way, when I peddle, it will turn the hub motor which will of course turn the rear wheel hub. When I whack back on the throttle the motor will turn the back wheel, but not the front peddles thanks to the freewheel cog on the motor ...

Not crazy, you couldn't be because I'm planning a similiar thing

Ok, some of my details are different (rear 9C motor driving a NuVinci from the disk mount, both mid-mounted) but still a similar design. I've already obtained my motor, controller etc (courtesy of Hyena) and most of the tubing for the custom frame, but I still have to complete my first custom so I will be watching with bated breathe!

Good luck,
GT

 

[dogman dan]

I'm with Drunkskunk on this. Your expectations pretty much describe a stock 9 c kit. My racing bike, a 9c on 100v goes way past that. However, riding it under 20 mph is pretty tricky.

I bet you'd be really happy with another of my bikes. 9c 2807 motor with 72v 20 amp controller from Lyens. It starts out mild enough, but develops about 35 mph after 1000 feet. Still nice and controllable at low speeds unlike the higher amp rigs.

But then you'd lose out on all the fun of designing your drive train, and wouldn't have the ability to low range it up hills.

 

[texaspyro]

My vision is that of an almost entirely custom made electric bike build.

I have a vision, too. But mine involves Halle Berry, me, and whipped cream

 

[gtadmin]

My vision is that of an almost entirely custom made electric bike build.

I have a vision, too. But mine involves Halle Berry, me, and whipped cream

Err .... that's not a vision, it's a err .... fantasy :lol:

 

[bringageek]

Well I'm glad to hear that most of my expectations for performance aren't so out there as I had secretly worried! Thanks so much everyone.

Drunkskunk you especially, the amount of interest you've taken in my project is really appreciated. And the info is great!

Let's start with the part about the mid-drive approach. The main reason I initially favoured this approach was that it was (or so I thought at the time) was going to offer me the ability to get the performance I was looking for at lower power. I didn't realize that what I wanted in performance was as obtainable as I initially thought. From what I've read from you folks it would appear that this is more likely to end up causing me more headache in the long run. And end up costing me more cash. And even causing an overall loss in performance. I'm considering abandoning the idea. We'll see...


I'd like to look at a couple of things separately. Sort of one at a time to make understanding easier for me. Because it'll take me a little time to digest all of this, I'm going to do a new post for each one of them. First item is below.


Let's start with the Archer 8 speed internal. Prior to now, the bike that I was riding was setup with a 7 speed freewheel cluster on the back, and just a single ring on the front. The front was setup with a 44t. And the rear cluster was a 34-24-22-20-18-16-14. I really liked the range that it gave me. To avoid headache I get when looking at gear ratios I use the words easy/easier and hard/harder rather than the high/low/mid et cetera to keep my head on straight. (Gear 1 being Easiest, Gear 2 being Harder, et cetera all the way up to Gear 7/8 being Hardest)

According to the gear calculator from Sheldon Brown (with the wheel size and crank length that I have) I have Gain Ratios of (2.3, 3.3, 3.6, 3.9, 4.4, 4.9 and 5.6).

If I were to outfit that same bike (crank length and wheel size the same) with the Archer Wide-Ratio 8speed, a 20t sprocket attached to it, and a 25t BMX chainwheel on the front, I would end up with a gain ratio set of 2.2, 2.9, 3.3, 3.8, 4.3, 4.9, 5.6 and 7.3.

Now if I understand all this correctly, I would be able to have roughly the same functionality with this setup. In fact, it would be ever so slightly easier to pedal at Gear 1 (Easiest), at Gear 7 it would be equally as hard to pedal as the original, and in fact, with the added bonus of Gear 8 being even harder to pedal.



Do I understand that all correctly?

 

[gtadmin]

Yes (to your post).

I wouldn't give up on your original idea though until you have read this

GT

 

[bringageek]

Alright... So there is one area that I've confirmed I have a solid grasp on.

Now for the next item of business... Belts.

Miles, you mentioned that I needed to do some more research, and you're probably quite right. But a couple of things I wanted to kind of explore. First off, there is a belt drive system that has been designed specifically for bicycles called Gates Carbon Drive. So clearly the idea has some merit. Also, belts are often used on motorcycles and dirtbikes. If a belt can handle the torque of a motorcycle, certainly a bike would be a breeze?

I like the belt drive concept especially because of the cleanliness. No matter how much I try to keep my gears and chain properly lubricated and generally clear of debris, it always ends up looking terrible. With the belts not requiring lubrication, means less for dirt and grime to stick too.

Perhaps I'm looking at the wrong belt type/size.


Thoughts?

 

[Rassy]

Check out the belts Recumpence used on his newest project.

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=25727&start=30

 

[Miles]

Perhaps I'm looking at the wrong belt type/size.

Yes.

The Gates Carbon Drive system for bikes is 11mm pitch. So, not much scope for size reduction there.......

You could probably use 8M PowerGrip or PolyChain, depending on the torque levels versus acceptable belt width.

Gates have a system for tandems, based on standard 8M PolyChain belts.

The smallest recommended sprocket for 8M belts is 22t. I've used as small as 16t with 8M PowerGrip GT3 but 11t is out of the question.

General info: http://www.endless-sphere.com/forums/viewtopic.php?p=126539#p126539

 

[bringageek]

Thanks Miles! The addition Carbon Fiber strands in the PolyGrip really probably adds that extra "edge" at the 8mm pitch. I've got a better look at the overall viability of this aspect of vision. I really appreciate your help. One thing I did want to mention is that the the Sturmey Archer 8speed being a wide ratio I actually don't need a huge reduction in size/tooth count from the front to back. Which, I believe, means my selection options don't require me to select from the smallest 5 or 10 sizes and the largest 5 or 10 sizes. I pretty much can pick anything I want. I'll come back to this later on in the planning/fabrication as I can always just fall back on a chain drive without actually editing pretty much anything, except for maybe a spacer ring here and there.



The next thing I wanted to look at was battery selection. As it stands right now, long distances over much more than about 10 to 15 km round trip on a day of a couple of errands around my area. If I were able to actually get 50km round trip I could actually make it all the way to my nearest IKEA and back. Which could dangerous... I swear those Sweedish people put something in those meatballs of theirs that makes you put stuff in shopping carts. And then spend the next hour trying to figure out how you're going to get all that into a car. Anyway..... Side tracked. 50km range isn't necessary, consider it a frill at the point.

What I did wonder about is choosing between 36 and 48V. And generally the more Ah in a battery is essentially like more gas in the gas tank, correct?

Going with a Lithium battery seems like a bit of a no-brainer. It appears the LiFEPO4 seems to be the variety of the masses. And just out of interest... Has anyone else notices that if you try to pronounce LiFEPO4 as if it were are word or a vanity plate it sounds like "Life Before" is said quickly? Kinda interesting, oui?

And what's the dealio with some of these batteries listed as 37V or 38.4V?
And as for PING brand batteries -- am I correct in understanding that they are budget batteries that have the advantage of a generally much lower cost than other "name brand" packs, but the disadvantage of a slightly lower quality? What I'd really like to know, is what are these disadvantages specifically and for me, what are the practical implications?


What I might consider doing, dependant on responses from you soon to come is start off with some smaller (lower Ah) PINGs to get me up and running and doing my local errands, and then upgrading 6 months from now. That way I can spend more in the custom frame fabrication. Or even look at other bells and whistles. Not literally silly!





Well, that's all for tonight -- my fart sack awaits!

 

[bringageek]

One other thing about the batteries I was wondering was with regards to the series/parallel configuration.

The switch idea that was mentioned which would allow me to go from a legal 32km top speed to an on demand WOOOOWEEE! top speed does that essentially change as I think it would. In series it would be 36v with roughly 20Ah of juice (2 x 10Ah batteries) giving me the lower top speed. And in parallel it would effectively function as 72v at 10Ah? Or is that backwards?

 

[gtadmin]

Backwards. Parallel = 36V20Ah, Series=72V10Ah

 

[el_walto]

Unless you are climbing steep hills all the time you really should consider a direct drive hub motor.

Get a 40Amp 36-72V controller. Use a Cycle Analyst to adjust your maximum power/speed output. You can start by setting it at 20Amps 32km/h and see how that goes.

Adding a switch for powerboost would probably make things more complicated then necessary. It would be nice if the cycle analyst had an option of switching between 2 power/speed profiles on the fly though, instead of having to go into the settings menu.

Unfortunately there seems to be a shortage of quality plug and play battery packs with high discharge rates, or maybe sticker shock just scares people away. That being said, I've been very happy with both of my ping battery packs with thousands of KM on each of them. The main problem with ping batteries is that you have to buy a large battery to be able to draw a large amounts of current from them. I only usually only use about 6Ah of my battery before charging but I have 30Ah of battery on my bike. I need the large battery to be able to pull 40Amps from it without causing damage to the cells.

you may also want to poke around at ebikes.ca or ebikekit.com if you haven't checked out those venders.