Trike and 2 wheel drive abandoned going for rear hub

[gonzales]

EDIT : I abondoned the 2 wheel setup after more thinking and more advises
just going rear hub now . Is crystalite any good HT series?
http://shop.crystalyte-europe.com/product.php?productid=16445&mode=download&file_id=66


Hello.
I own a trike like this one.

In the past i already Built a 48V 1000W Hub to the back wheel.
But is was just a normal hub motor(Low torque on low speed) so it broke after a year Cause of the high weight.
The loaded ride is about 200Kg-250Kg.
Wheels: Rearwheel 26" / Frontwheels 20" (Smaller wheels for more torque cant be done or the pedals hit the ground and they need to stay)

I looked for some alternate option:
- A geared Hub motor (Gears will not last long). Or will they ? replacement once a year is not so bad maybe?
- A Mid motor (I Got no clue on how to get it done whitout turning into a Gear/converter belt/chain monster).
- 2wd setup/ 2 Hubs in the front ... (i Saw an entire sticky post about it here and now i am interested).
Since the front wheels are 20" ill get more torque due to dual / size.
I have read the 2WD post but still need help.

Since the trikes steering is fixed on the loading part the wheels should turn 100% syncronized. (It would be not drivable if not good sync)

What do i need to get this done ?
I still got a big 48V battery Wired to a 25Amp controller.
I guess the controller is of no use anymore. But should i get 2 24V controllers connect the in series ? or 2 48V parallel ?
Sorry If i sound stupid or my grammer is poor but your help is welcome.
Thank you.

In the making of this post i think of a problem.
The steering is so stupidly made for this to work.
If i give some power and the Left wheel is in a sand part and the Right wheel on asfalt the left wheel will maybe skid. And will probably insantly force steer in the left side
And I cant mechanicly lock/sync the wheels either. Damn

 

[Drunkskunk]

Because of the way that front end is designed, front wheel drive will always be fighting you. That may not be a serious problem, but you'll always be wrestling with torque steer.

A pair of good low speed hub motors should work for you. Something designed for 20kph at 48 volts would be able to handle the weight much better than a pair of motors designed for 30+kph.

Geared motors will make better torque, but the only geared motors I would try would be the BMP or MAC motors. They should be ok.

For direct drive, I think Dogman may know more about them, but ebikekit.com sells a low speed motor that would work.

Your battery might not be usable. 2 motors will draw twice the current, so if you use two 25a controllers, the battery will need to be able to handle 50 amps continuous.


If that bike was mine, I'd be looking for a way to use a chain drive and put both wheels on an axle with a gocart differential. But I imagine that will take a considerable amount of fabricating to accomplish.

 

[John in CR]

You'd want a way to tune the controllers for identical current, so they'll pull straight while cruising. To overcome tendency for the trike to want to straighten itself out during turns you could do side-by-side ebrake cutoff buttons, one for each motor, in addition to the brake levers that cut the power of both. Then when you're turning left, you push the left button and the right side motor will help you turn. It will take a bit of getting accustomed to, but I think it could work quite well, even better than the rear motor alone, since you would have turn assist.

 

[teklektik]

I think from your trailing remarks you see some of the difficulties in making this work.

Unlike other designs where unequal steering forces are countered to some extent by the moment arm to the wheel(s) at the other end of the bike, your setup seems free to rotate unless restrained by the rider or the other wheel. I'm not sure I would characterize it as unstable, but 'nightmarish' comes to mind.

To power both wheels, you will need a control system that actually tracks individual wheel rotation like a Segway and effectively gives power steering by active motor control. Any crude attempt to balance controller currents with stock controllers cannot reasonably work as the smallest imbalance in applied power will cause the whole bucket to rotate instead of simply speeding up the other wheel as in a more conventional 2WD setup.

IMHO you are asking for trouble by going to 2WD - there are no off-the-shelf control systems to make this work and the whole steering issue is an inherited headache that has nothing to do with your simple desire to power the bike - it's an artifact of the proposed solution. So don't use that solution.

Go back to RWD.
My guess is that this thing doesn't go very fast so maybe 10mph is top speed - so you a definitely in a low rpm situation that will make a DD rear hubbie suck amps and make heat.

My knee-jerk solution is to chain a MAC 12T up to a sprocket bolted to a disk brake adapter on the rear wheel. This gives you a very torquey motor, additional torque from a 2:1 gear-down, a freewheel for free, and lets you keep the 48v battery. We don't know about your riding situation, but I'm guessing you are getting along without a motor now, so we aren't too concerned about climbing long hills, etc (?). A big problem that I see is that it looks like you may have a 3-speed hub on the back or something like that so swapping to a hub with a disk brake mount might be problematic.

To mount the motor you might either have a ruggedized custom rear rack welded on and mount the motor on dropout slots above the rear wheel close to the seat - or - you could get StokeMonkey mounting parts and mount the motor in front of the seat tube. There is always the option of using the standard StokeMonkey though-the pedal-chain drive, but I was trying to run the motor chain in parallel for redundancy. Of course, you might also just use the whole stock StokeMonkey setup and just lower the gearing a bit. That would make it pretty much plug and play if your rear hub could take the torque.

You have a pretty funky BB setup - I'm not sure if you could fit a BBS02 with small chainring in there or not... (I have no experience with those drives).

Anyhow - just some thoughts...

 

[ddk]

-simplest solution-
low-speed geared-hub motors on the right/left front wheels with right-hand and left-hand throttles.
--problem solved--

caveat-
I use throttles mounted left/right on the same handlebar side on MT trike and opposite handlebar sides on MPPM trike with no apparent issues i.e both methods feel natural to me.

 

[teklektik]

-simplest solution-
low-speed geared-hub motors on the right/left front wheels with right-hand and left-hand throttles.
--problem solved--

I doubt it - this front end has too much oversteer. Any small drive imbalance will swing the front end into a turn that has no tendency to self-right - hardly something you'd like to occur at 5 or 10 mph. Just too finicky and dangerous. The swiveling front end makes this different than the classic tank/ATV/lawn mower dual sided drive where the turning geometry does not change in a variable way with power application.

I could be wrong, but.....

 

[gonzales]

Yes a day at work thinking let me drop te 2wd on this rig too olmost impossible. If i get it syncronized 100% there is still the turning problem.
And i like the E-brake turning idea but it would be more an experiment doomed to fail or have some bad issues.
So back to rearwheel.

Some more info:
-My wife drives slow speeds
-And the bike must not look like a transformer whit extra chains and reduction wheels cause it attracts enouf attention anyways.
And i dont want the cops stopping me cause they see "strange" things. A Hub is no problem they think its a brake or something (local village cops).
On my previous HUB i got to high speeds but one time on a long downhill i overdid it and i nearly crashed (empty box) Somesort of swing effect , wiggle wiggle on 2 wheels from left to right so i never did that again) LIKE teklektik said in previous post ... But in fact the ride was very stable untill 20Mph.
offcourse not made for high speeds but hey it was so niceovertaking real cyclists whit them spandex outfits on a big trike hehe
I wished it went about 25Kmh instead of +-40Kmh on the last hub.

I have seen the MAC T12 several times on my search for a high torque motor.
But would someone please think of the gears vs 200kg/250kg
Would they survive for 2 days or 2 weeks or half a year ???

And what dou you mean by the brake disc mounting ?

What about a Fixed hub motor custom coils or magnets or something to get far lower speed / more torque ???
My previous was whitout any sensors just give power and go .
what if i use hall sensors or torque sensors ore something ? would this be somsort of help not overdoing the motors power on acceleration from very low speed?
I dont know much sorry there is so much info everywhere it drives me nuts.

What about this motor ? http://shop.crystalyte-europe.com/product.php?productid=16445&mode=download&file_id=66
Cristalite HT 2535 ? at 285Euro its affordable and little more on the torque minded maybe it wil live 2 years ?
(My last one was 160Dollar spoked on a 26" wheel cheap and lazy. Now i got a nice bikeshop owners help for spoking it )

 

[amberwolf]

I'd just go with a rear wheel drive.

If you don't wanna drive thru the chain (which would let you build a stronger wheel if that's part of your problem), then just a rear hubmotor would be simplest, and can be perfectly reliable as long as the wheel is made from good parts and built well (unlike most of the ones that come prebuilt on the hubmotors, which can be usably alright or can be complete junk).


If you really want to go with dual front hubs on that trike design, well, it's not the way I would go because it's awfully complex, but if you were into Arduino (or similar) programming, and electronics / hardware design, you could figure out a sensor setup that determines torque/speed on each wheel and/or how far off-center the steering is now and which way it's going and/or senses pressure of your hands on the grips/bars, to see if they are equal or not, and if they are indeed trying to steer it into the direction it's going or if it's trying to fight it, and then throttle the motors appropriately to help steer.

It might not be quite as complex as it sounds, but it'd probably take some working-out of the system after you design it, to get it to work the way you want in even extreme situations (where it would make the most difference between riding and crashing from oversteer).

(A long time ago, I pondered something like this for a possible trike design and abandoned it because it ended up too complex to try with what I had available in parts and know-how, though the trike itself was a lot simpler to build, from what I could see of all the ice-cream vendors that pedal similar types around here).

 

[agniusm]

Its too complicated for this. Arduino and all is fun but there is no need. Rear wheel drive is perfect. If you broke the wheel put your effort in sourcing and building srtonger wheel. Check what you can fit, go with a steel rim and high torque motor plus beefy bolted torque arms. Mount your battery and electronics at the back for littlw better traction and you'll be fine.

 

[gonzales]

Its the previous cheap motor that broke.

My big battery is worked in a plexyglass box with thick aluminium bottom (whit a big rigid oversized 63A plug that will outlive the battery )
that "battery box" fits perfectly underneat the front bench and easy to take out or replug for charging and waterproof.
Worked the wires in a small pvc cable duct to the controller.
The controller Underneat the rear bench mounted on the side whit some enbankment struts so it "floats" for cooling with a small plexy front cover to prevent raining on it. all the wiring stuffed away in a small piece 40*60 pvc cable duct.
2 small black cables to thump throtthle and 1 brake lever switch. whit the very small pvc cable duct in the middle streight up to the steering wheel.
Only 3 black 6mm² wires underneath the wood along the frame to the midle where it goed under the main frame bar to the hub motor.

Stealty setup only the Big hub motor is something u instantly see. the old one even had big samurai style signs engraved all over
but hey it was cheap and good for first e-bike project! i bet if i had it on a normal bike it would still work. the big weight killed it.

for not making it to complicated and sucking out all my money i think of replacing it whit a crystalite HT3525 (high torque) one. Little less "tuning style"...
A bit less speed then my last (thats what i need) , a bit more quality (i hope) for about 345euro mounted on a high quality 26" Rim.
If it lasts 2 years i am happy

 

[Martin A]

Just a thought here on 2wd and steering but I'm no electronics expert.

If there was an rpm sensor at the rear and on each front wheel would it not be possible to match the speeds of each front wheel when going straight through some sort of simple electronic differential controller matching the speed of a slave right wheel to a dominant left wheel. I.e the normal throttle controls the speed of the left wheel and the speed of the other wheel is matched to this in the straight ahead condition.

This condition would be determined by left wheel rpm to rear wheel rpm 1:1 if both are the same size and then right wheel is set at 1:1 by the controller. If the steering is turned then the ratio of left to rear might be 0.9:1 so the ratio of right to rear could then be controlled to be the inverse i.e 1.1:1. (These figures would naturally be determined by measurement first, ideally using the sensors while the wheels are free wheeling and not being powered)

While I'm aware that this would not be perfect we have to realize that an ounce of rubber is worth a ton of theory and that differences in the theoretically perfect solution and the simple fit one proposed may well be take up by the distortion of the tires just like they are in many automotive applications where a limited slip differential is used.

Alternatively, steering could just cut power to one of the front wheels, which would then be free to rotate at any speed necessary for perfect differential action. Although I realize this would then result in a loss of power but then one is unlikely to need full power while negotiating a turn.

 

[dogman dan]

You need the slowest RPM direct drive motor you can find. Or perhaps, gear super low with a bottom bracket motor.

To lower the rpm of a hubmotor, it would help if you could also make the rear wheel smaller. You'd have to weld or bolt on some kind of frame extender, so the pedals don't hit the ground after the change.

If you get to where 36v is only going 10-15 mph, that should do it.

The other option, is go huge. Get a monster motor, one able to handle 3000w or more. Then run it on only 1500-2000w. The larger magnets in the motor will run slow under load more efficiently (cooler) than any skinny motor. And running it on only 1500w will mean you never get close to running too much power into the motor.