need some help for an arm-powered offroad recumbent

[adrian_sm]

Yeah, I would just go for a simple hub motor as dogman said to get up and running, put the throttle on your secondary brake/steering arms, and you are up and running. Go for some rides and keep an eye on motor temps (should be able to just reach back and feel it when you have pulled over). Then if the motor survives the sort of terrain you are throwing at it all good. If not you may need to swap the hub motor, for something that uses your gearing. As long as you don't cook the motor you should be able to sell it off, and not be out of pocket much.

If you get a controller that is capable of making use of a PAS/pedelec sensor you can try this out latter. This should be pretty common. But I am not sure how common ones that accept a torque sensor on the cranks is, this would require a bit more research, or maybe someone here knows where to get one. Obviously if you can get one that can do both, you can try out some of the things we have been talking about relatively easily.

Gut feel is you will probably want to use the gear with a stokemonkey/elation/cyclone style setup, but a geared hub motor will be the quickest and easiest to set up and may do the job.

Here are some links:
http://www.ebikes.ca/store/store_ezee.php - Geared hub, with PAS
http://www.ebikes.ca/store/store_stokemonkey.php - Stoke Monkey that lets you use your drive line gearing

- Adrian

 

[MadRhino]

Stoke monkey seem to be the perfect setup for this purpose, or any kind of custom mid-drive, cause shifting gears is the best way to be efficient in climbing. Use a controller that has pedelec capability even if you plan a throttle first, cause pedal assist is probably the control that you will prefer after experiment.

 

[AussieJester]

Good to have another para on the forums! As to which setup, non frock (hub) motor setup all the way..

Best ofluck ..

KiM

 

[LI-ghtcycle]

Welcome Scott!

There is indeed a wealth of information on this site! Get ready to drink from the fire hose! :lol:

I think you would be best served with a form of mid-drive personally, as you have stated, your goal is low speed high torque hill climbing.

No mater what hub motor you select, there will be generally a narrow application especially off-road to keep any hub motor in it's effective climbing "power band".

Don't get me wrong, knowing the limitations of the hardware, and keeping track of the hub motor's heat and speed can allow you many years of trouble free operation with minimal trouble, however, I would strongly recommend that you stay with the higher out-put hub motors (500W or more) and realize that you are either going to need to out-cool and out voltage them to get the performance you want, or accept much greater limitations over a mid-drive.

Not all mid-drive set ups are terribly pricey or difficult to install.

Given the handiwork that is the off-road hand bike in question, this would be child's play for you builder.

I am currently putting together a low cost mid-drive that will rival the price of a hub motor and battery using a similar platform in the form of a recumbent two wheel bicycle (Vision R40) with a 650W "Trike Motor" sold by Golden Motor.

http://www.goldenmotor.com/

This motor will allow me to take a mid-drive using closer to just 1000W of power and accomplish what would require easily 2000W of power with a comparable hub motor set up for one simple reason: gearing.

The simplicity and ease of operation of a hub motor can no be beat, however, it has some limitations, namely, the diameter of the wheel that the motor is laced into is the set "gearing" it is restricted to, and unless it is a geared motor, this means it is inherently inefficient (think of a tractor with only one working gear in the transmission, too low and it will never give you speed, too high, and the motor will struggle most of the time against the too tall gearing until it reaches the optimal speed it is geared for, however, the hub motors, especially the direct drives are pretty forgiving, much like a tractor motor, but not very efficient unless traveling at enough speed, which it would seem is not what you are looking for, but a hill climber).

I have a favorite model of DD (direct drive) hub motor, most commonly called a "9C" or nine continents motor. The one that I have that also just happens to be one of the most versatile is the 9 x 7 winding motor made by Amped Bikes.

This is not a low speed motor, more on the high speed side, but it generally will give you good performance just by adjusting the voltage given to it (high voltage increases RPM's of the motor, thus generally efficiency and top speed).

With just 48V of the standard Lithium Iron Phosphate battery (LiFeP04), this motor will charge up the local hill of 10% - 5% grade at 12 MPH and not break a sweat or get hot, this hill is about 2 miles long. This is from a no-pedal start, on even steeper than 10% grade going over rail road tracks at the beginning, this motor quickly took my 180lbs body and a 75lb E-Bike up to 12MPH very quickly and maintained it no problem.

However, using this very same motor separated from the wheel, acting as a mid-drive, similar in principal to how the stoke monkey works, I was able to do the exact same task on 3 separate occasions each time using only about 34% of the same energy!!

This means, with less battery, you can do more, or dramatically increase your range with a current battery. This sounds incredible until you realize that the motor being out of it's efficiency zone lugging around at slow speeds converts about 50 - 60% of the battery power or watts to heat instead of working force propelling you forward.

With the proper gearing, this same motor moving in it's most efficient speed, not only cools it's self more naturally because it is spinning faster, but will convert that same amount of watts into up to 80% of the power given into working force and very much less heat.

Also, especially if you are wanting slow speed up steep grades off-road where you're likely to have to stop and start again on such steep grades, you risk the very real possibility of burning up a DD hub motor or even a geared hub motor (remember, the geared hub motor still needs to be able to turn that wheel at a certain minimum speed to remain efficient, and geared hubs have a much harder time shedding heat than DD hubs) at too low of a speed.

Many of the mid-drive systems off the shelf are going to put you very close or over that $1500 budget including a battery to go with it (considering an average battery to do what you need will be in the $400 - $600 range) but as I said before, there are other solutions that would be well with-in that range, especially with the many more options that come with using a recumbent trike as the platform for installation.

A very simple easy to construct design would be one built by Rassy using the same 9C motor at a different winding (6 x 10 if I remember) here:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=18606&p=271230#p271230

(Most of the pictures aren't working but should be remedied soon.)

And there are others that have higher powered systems that allow incredible power using very powerful R/C motors used in large scale model helicopters and such that can go 40+MPH!!

My own set-up will be using a 45V Lithium Polymer Battery (LiPo, if LiFeP04 is aviation gass, then LiPo is Top Fuel Dragster stuff! ) and using a NuVinci CVPT (Think automatic transmission like in a car, but with unlimited "gears" between the 350% range) as the transmission for both my motor and the pedals.

My build link is here:

http://endless-sphere.com/forums/viewtopic.php?f=3&t=29810

Just to give you an idea of costs (shipping included):

Motor ...............................$167.00
Custom Lyen Controller..........$189.00
Battery & Charger etc............$650.00
NuVinci Hub & Custom Wheel ..$399.00
Misc. Gears/brackets etc. ......$200.00

Total ..............................$1605.00

And this is on the high-end, you could easily take $200 off that by using lower cost "over night" battery chargers and such (I am using something that will easily charge my battery as a whole in 1 hour or less) and even more using a hub motor, but for the variety of off-road performance and street performance it's pretty hard to beat.

You could also save another $79 and buy one of the "Developers Kits" type of the NuVinci hubs for $150 instead of $229 and have an automatically shifting NuVinci rear hub that would be pre-programmed by you to do any number of functions including maintaining the same RPM at the pedals regardless of the speed/load you are presented with (hills, higher speed on flat ground etc.) that would allow you to have the exact same cadence or RPM at the pedals at all times!

Here is a link to the Developer's kit for purchasing as well as other ES members who are using them:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=30641

I know it adds more complexity, but given the application, I would think an automatic shifting rear hub might be really useful for your purposes.

Again welcome to ES!!

And I am also excited to see what you come up with, any way we can help you with information (I know you're just trying to stay above water reading all this information he he, I know I was when I first came here! ) please let us know!

 

[amberwolf]

Interesting concept. Honestly, it'll be a lot easier to use off-the-shelf parts vs. something custom, plus we need the ability to control front & rear brakes separately.

It would definitely be easier to build the system you have now than what I'm thinking of, but *using* the alternate system would almost certainly be easier (or at least, give you much faster reaction time for braking vs accelerating, since you wouldn't have to move your hands off the cranks).

But either way, you can easily control each side separately--there would be a set of slip rings on each crank, and each one would be independent of the other, activated by it's own lever.

The only control you can't use this way is a shifter, because it must maintain the tension even while turning--to do that, you'd need a setup with bearings on the rings, and that would be more complex and require more precise machining than these other rings for braking.

 

[dogman dan]

Interesting post LI-ghtcycle.

I couldn't agree more that a fast winding dd motor is not what he needs. But a slower winding does do a lot more climbing with a lot less heat.

Part of why the stokemonkey set up evolved was avaliability of good brushless hubmotors when a lot of the affordable scooter type motors were still brushed. The motor you just showed makes using a hubmotor for a chain drive less of a requirement. It also may fit on the kind of bike he's using. The stokemonkey is popular on longtail bikes that have a ton of room for the motor.

Again, there is no doubt a chain drive can be geared lowest. But a 2812 9c in a 20" rim is geared pretty dang low. Low enough for me to ride up most of my local trails without pedaling at all. I get pretty amazing wh/mi on mine for the kind of riding. About 30% lower than I would with a 2807 wheel.

 

[scottpruett]

Holy information overload. You guys are super helpful. This is going to take me some time to digest & figure out.

LI-ghtcycle, thanks for taking the time to reply w/ all that. I'm quickly realizing that there are a lot of little details that are worth paying attention to now vs. later... and wow, that NuVinci hub looks interesting for sure!

 

[LI-ghtcycle]

Interesting post LI-ghtcycle.

I couldn't agree more that a fast winding dd motor is not what he needs. But a slower winding does do a lot more climbing with a lot less heat.

Part of why the stokemonkey set up evolved was avaliability of good brushless hubmotors when a lot of the affordable scooter type motors were still brushed. The motor you just showed makes using a hubmotor for a chain drive less of a requirement. It also may fit on the kind of bike he's using. The stokemonkey is popular on longtail bikes that have a ton of room for the motor.

Again, there is no doubt a chain drive can be geared lowest. But a 2812 9c in a 20" rim is geared pretty dang low. Low enough for me to ride up most of my local trails without pedaling at all. I get pretty amazing wh/mi on mine for the kind of riding. About 30% lower than I would with a 2807 wheel.

You are the expert when it comes to low speed off-road applications for a hub motor, and I tip my hat to you!

I'm not trying to say a hub motor can't or won't get the job done, but for me, now that I have played with a mid-drive and realized it's potential, it just makes more sense, and given that he is using the perfect bike type for either a mid-drive hub motor or one similar to my project, I wanted to just give another option too.

What kind of wh/mile do you get with the same set-up for the low speed off-road using it on the street? I'm guessing it just has a lower top speed than the average DD hub motor set-up specifically for the street?

I must admit that the motor I have coming in the mail is still an unknown until I have some testing in, on paper it looks to be ideal, but that means nothing until I get some real world testing in.

 

[scottpruett]

Interesting post LI-ghtcycle.

I couldn't agree more that a fast winding dd motor is not what he needs. But a slower winding does do a lot more climbing with a lot less heat.

Part of why the stokemonkey set up evolved was avaliability of good brushless hubmotors when a lot of the affordable scooter type motors were still brushed. The motor you just showed makes using a hubmotor for a chain drive less of a requirement. It also may fit on the kind of bike he's using. The stokemonkey is popular on longtail bikes that have a ton of room for the motor.

Again, there is no doubt a chain drive can be geared lowest. But a 2812 9c in a 20" rim is geared pretty dang low. Low enough for me to ride up most of my local trails without pedaling at all. I get pretty amazing wh/mi on mine for the kind of riding. About 30% lower than I would with a 2807 wheel.

Alrighty... life is getting a little less busy & I'm finally getting back to this.

I'm thinking a hub motor as dogman described above may be what works best without too much complexity (or expense?). I'm having a tricky time finding a 2812 motor though; am I just looking in the wrong places, or does it go by another name? Are there other options w/ similar capabilities? Dropping to a 20" rim shouldn't be an issue if that gives us lower gearing, as we'll likely build another frame.

Question though... being that this rig is hand-driven, it may be tough to apply throttle continuously while "pedaling." Is there a controller that permits pedal assist w/o holding down a throttle?

 

[ptd]

Question though... being that this rig is hand-driven, it may be tough to apply throttle continuously while "pedaling." Is there a controller that permits pedal assist w/o holding down a throttle?

that's exactly why i suggested the pedelec. most of them even support variable levels of assist. sorry, not sure which controllers support that option. shouldn't be too hard to find someone on here that knows though. or maybe just pick the brains of a few retailers. there's a lot of kits that come with that as the standard option. iirc, most european regulations even require it.

as for the 2812, i never found one, but i was looking for a 26 inch wheel. iirc, methods may have one, and even in a 20 inch configuration. and it was really inexpensive. he'd be able to set you up with the right controller too i bet. here's the post i saw http://endless-sphere.com/forums/viewtopic.php?f=31&t=26603

 

[itselectric]

I'm working with a friend who builds offroad handcycles for people with disabilities (both he and I have spinal cord injuries & are end-users). He's got a prototype of a hand-powered recumbent that we're considering electric assist for. Thing is, neither of us know the e-bike world well at all.

Any other ideas are welcome!

Thanks,
Scott

Scott:

Here is video one of the handcycle that we help to convert, we didn't use the cheap pedal speed senor (either too fast or too slow), but we use the cruise control to lock in for the speed. We are just right in middle of testing bottom bracket torque sensor:
[youtube]5IRqt1bjx5c[/youtube]

Here are a few picture of differ version of HandCycle.
View attachment 3




All the HandCycle that we have done were more for urban, not for off-road, but they all works very well.

Ken

 

[ptd]

anyone care to venture a guess as to what ungodly sum of cash they'll charge for this thing ? you might keep in mind that they appear to be a retailer for bionx. and charge $835 for a 48v10ah lifepo4 and charger. my guess is that they'll try to secure disability funding somehow, and ask about $8,000. for a $2000 bike. on a positive note, it IS some good work. the widened 'cranks' seem like they would make steering easier and more responsive. and the ability to adjust the stance is very innovative.

i'm suprised that you don't consider ditching the wheelchair altogether, we have the main principle of altering the wheelbase here, why not take it 2 or 3 steps past that. seems like the width is pretty comparable. of course there's probably a stability issue, by raising the occupant's height. you could probably get landing gear to handle that. make it part of the 'rear frame', being on a giant pivot point at the chain transfer point behind the seat. ok, i know it sounds a little transformer'ish, but damn. maybe the bicycle version of the Toyota i-REAL. it's even a tilter. helps the stability issue. i'll stop short of suggesting gyroscopic flywheels. i guess another problem would be getting the steering/cranks out of your lap, although i'm thinking you could have another pivot for that. so that the 'bar' rotates forward and down and becomes support just below the knees. ok, can't get the transformers soundbite out of my head, lol, but talk about an interesting foray into geometry. and then you'd need some serious gearing down of the motor. i don't think hub would work.

lastly, and back to reality, the simple (and cheap) solutions are usually the best ones. but that's a lot harder to capitalize on, isn't it. how bout just a single pushbutton on the 'pedal', with rf (like rc, in a fly by wire sorta way), to signal the contoller to maintain speed. isn't set and forget cruise all but banned on ebikes now ? for safety issues ? especially when you consider that in this case there's an additional step in deactivating it ? if your hands are on the pedals, that is. i still like the idea of a pedelec registering negative torque by backpedaling, resulting in regen braking on a hub motor.

 

[scottpruett]

@ptd, thanks. I'm learning about this technology as we speak. A few weeks ago I didn't quite understand pedalec. A push-button throttle on the "pedal" is an okay idea, though some riders this bike is tailored for (myself included) have spinal cord damage that results in limited hand function. I'm still sorting through (and learning about) various options.

I'm wondering if the BionX setup might work well...

@itselectric, good thoughts for sure, but there are a lot of differences between the bike you posted & one for lower-speeds offroad. thanks though.

 

[ptd]

@ptd, thanks. I'm learning about this technology as we speak. A few weeks ago I didn't quite understand pedalec. A push-button throttle on the "pedal" is an okay idea, though some riders this bike is tailored for (myself included) have spinal cord damage that results in limited hand function. I'm still sorting through (and learning about) various options.

I'm wondering if the BionX setup might work well...

@itselectric, good thoughts for sure, but there are a lot of differences between the bike you posted & one for lower-speeds offroad. thanks though.

i was suggesting the pushbutton, not for a throttle, but for a cruise function. regardless of the amount of input to the pedelec. it doesn't have to be a pushbutton, it could be a rocker switch. i just like the idea that when you reached for the brakes, you'd naturally release it.

as for limited hand function, i still like the idea of backpedaling causing negative input on the pedelec, resulting in regen braking on the motor. kinda like a coaster brake on bmx's and cruiser's. in a fly by wire (without the wire) kinda way. let's you keep your hands on the 'wheel'.

i wonder if someone makes a paddle throttle. it could operate throttle, or pedelec assist settings. like 2 buttons, one for incrementing and one for decrimenting. would be easy for a brake cutoff to reset it to 0. might also be easy to regulate how much time is spent above a max continuous C rating.

bionx might work, but it also might cost you through the nose.

as for low speeds and hub motors, from what i've learned so far, doesn't sound like a great mix. the hub motor wants to run at a certain speed to stay efficient, ergo, cool. through the gears, mid drive, setups, allows the motor to stay in it's 'comfort zone' for a multiple set of speeds. and user assist isn't a function of grade. you have the same power, but you will have slower speeds, and you'll be capable of higher grades, and variable amounts of pedaling. the downside, is a more difficult install, and more complex operation.

as for the more complex operation, this might be a unique situation, justifying even more electronic control. like paddle shifters. like electronically actuated brakes. seems like you could do away with the other steerers. and even with the rf transmitters and recievers, i think it wouldn't be more complicated than a control pad for an electric wheelchair. and the paddle shifters could be operated by the controller, the throttle and brake by the pedelec, the only thing on the handpedal would be the assist level. how's that for simple.

as for cost, you're probably in a position to subsidize most of it through disability. hell, i bet you could get a grant to research solutions for this. i can't see the costs being that much. some tiny drives and worm gears $50. rc transmitter $10. a small board $20. one spring loaded three position momentary rocker switch $4. and a pedelec $8. just guesses, but probably $100 in parts.

 

[theRealFury]

Well I just stumbled across this thread and its proved a really interesting read for me. I have a couple of questions and also want to share my opinion.

question 1, do the 2 separate drives change the gearing at each step so like a 2x step-down gearing system to increase torque at the expense of speed? If so then I can really see the benefit of a non hub motor drive such as an RC drive or cyclone kit.

My reasoning is that i would imagine that a pair of arms (on a normal person, not talking bodybuilder here) are not capable of putting out the same kind of pedal power as your average cyclists legs so let’s say that the average hand cyclist can put out 100-150w of power... a 500W RC drive would therefore using the same gearing give you the power of 3-5 sets of arms at the low end of the gearing for climbing hills and then using the derailleur on the back can also be used to give you a lot faster top end speed on flat or road surfaces due to more watts available.

With this low wattage heat should not be such an issue (unless you use a cyclone kit which I hear has heat problems), especially with such low gearing as you would use at the moment. Also the benefit would be large against a DD hub motor given that you would need to run even a slow wind DD hub at 1500-2000w to allow climbing of steep hills. The only benefit the DD hub would give in my eyes is that it would probably climb the average hill a little faster (albeit using lots more power).

As for throttle control... I’m sure it has already be done but could it not be possible to feed a hall sensor attached to the crank and then take the analogue signal from the hall and convert it (using something like an "arduino" or other IC) to a digital signal or convert the RPM blips from the hall to variable voltage for a throttle? So the faster you turn the cranks the more power the motor gets. That way you could decide if you wanted to stay in a high cadence gear and allow the motor to supply higher power or drop into a low cadence gear and share more of the toil.

 

[parabellum]

Do they have all the controls on pedals in last picture of itselectric? Looks like normal handles mounted as pedals are and all cables are just little longer and shaped to permit cadence action. So kind of grip throttle and break levers can just be in your hands all the time and you can still pedal. Think it is reasonable solution for safety. Is it practical?

As to motors, you do not need to go crazy from start on, it can result kind of dangerous if you new in it but reasonable sequence is to buy stock hi wind (torque)DD motor, maybe Lyens 150V controller (looking for future modification if necessary). 2x 48V battery's to have them parallel to start. AND you have working system you can ride with, no headache.
DD motor can always be converted to mid drive after you are tired of problem less, maintenance less system! :wink:
Welcome to ES! Very interesting tread!