What are the best ways to build a two wheel hub mounts e-bike?

OmniosTom

10 mW
Joined
Jul 16, 2013
Messages
32
Living in Canada I am interested in two wheel drive bikes for use on milder winter days when the streets are cleared. I read a lot about how two wheel hub mount bikes with larger tires namely 4" tires but looking at 3" or 3.5" tires for traction on snow. I am wondering if two small hub mounts say around 500 watts each would work. Will I require special parts and would the motors have to be balanced as in if I purchase two hub mounts they would have to match each other power delivery. Also is there special motor controllers for this or will you have to splice them. Is it even worth doing this? I have seen ready made e-bikes with two wheel drive but also read that both motors must match each others power ratings and output. Also do they actually make 3.5" tires for e-bikes?
 
I remember seeing a Micah Toll youtube video explaining this a few years ago. Seemed rather simple. Two controllers, sharing one throttle IIRC. He was doing two wheel burnouts on the beach!

Wide tires can be had but is there room for them on your frame?
 
Well, for snow riding, I would not want pedal actuated motors on the bike. Id have to have very fine throttle control. One throttle can control both wheels, but I might even want a throttle in each hand for two motors. Or maybe a push button on the left hand that simply allows the right throttle to actuate both motors, or just one, if you push on the button. Push the button, both motors run.

One thing to consider, if you put a motor on the front wheel, then pedaling the back wheel makes it two wheel drive.

Living in the desert, I had little experience with snow riding. But when it did snow, a regular rear wheel drive bike worked best for me. Why? Because what you need that front wheel to do, is maintain traction and steer. Once it locks up because of brakes, OR loses traction under power and spins out, you lose your steering. Living in the north, you must know what this means. You go in a straight line till you hit, whatever is out there. Or on a bike, simply lay it down. On a car, you might spin the front tires and be ok, because you won't lay down a car. On a bike, whamo.

I did do lots of front wheel motor riding, at power levels high enough to do power slides in dirt or asphalt. Controlling that on the front wheel was incredibly difficult compared to a rear wheel loss of traction. On a slick winter road, I'd call it impossible.

I'm not saying you cant do a two wheel, or front wheel bike. But when its like that, you will need real ice tires, with studs. Thats for ice. But if you ride in 6 inches of new snow on top of packed snow, you want the fat tire. One thing about a fat tire is you run 5 psi in them, and you get great traction. Possibly enough for ice. But the traction I mean is in anything soft and deep, like snow or sand. You stick your truck in the sand in the desert, you let some air out of your tires to get enough traction to get going again. Works on snow too, to get you going again.

Me, I'd go with a fat tire bike, and rear wheel motor. Id walk if the roads were so slick you cant ride the fat bike.

3 inch tires are a good compromise, but you might find it spendy. 3 inch tire won't fit most regular mtb's, but a good fat bike is spendy too. If its for plowed roads, regular mtb, and a 2 inch tire with studs might actually work best. You might even take two motors, and put them on two bikes. Ride that cheap as hell mtb with the studs on it only when you need to. Ride the fat bike when its 6 inches of new snow.
 
Chiming in here as I have recent experience with this, albeit less experience than others.

As far as 4 inch tires that would be considered actual fat bike territory and as a result you'll be dealing with some weird drop out spacings That someone limit the motor choices. There will be an assortment of generic Chinese direct drive, then bafang/mxus and mac pretty much.

personally don't like direct drive for low power applications as they feel sluggish and anemic off the line but if you want to get complex with some thing like a phaserunner perhaps you could probably Run a higher wattage off starting off and taper off as necessary. I've been running direct drive in the snow recently around 1200w peak and it works but with lower power you really notice the effort you have to put in. Plus it makes already heavy bikes heavy as shit, So if you were doing a plus size tire with two of those the thing would be a tank

Not sure if you already have a frame you plan on using but a lot of surly frames have good range of dropout and tire spacing and you could rock some 3 inch tires on normal dropout spacing to widen the range. Plus they are steel and a lot of times come with forks that are also steel So they make a good platform. Snow does take a lot of power to get through, Though if it's snowing, it would normally mean that it's pretty cold anyway and dividing the power between two hubs Should make it pretty manageable. If you're not planning on going at blazing speeds perhaps a pair of q100 or something could be a good match.

Dogman is right, PAS Sucks in this application particularly if it isn't Torque sensing, And especially with a lot of cheaper controllers that tend to have minute amounts of run on after you stop pedaling Which are a big no no in slippery conditions. At first I was using pedal assist off-road, and it made for a less than ideal experience. After reading some suggestions from people on here I disabled it And it made offering much more enjoyable. Truth be told if I was relying on it still, I probably wouldn't be going out in the snow

My snow rig now it's really just an older steel Hardtail family bike I've built to pull a trailer. Direct drive motor upfront and human powered in the rear, like a centaur

With less than ideal set up, I have no problem powering through a few inches of snow and plenty of grip surprisingly. I think tire selection plays a huge role here as well as the type of snow, but it is definitely possible to be TOO aggressive on tread pattern.
 
Lifting up our cold weather Ebike Riding Offerings. Luna has a kit to put a track on the rear of your bike for snow. Luna cycle snow bike.
 
I'm just thinking out loud, but would a rear geared motor and a front DD motor solve the steering problem? That slow, weak power delivery at low throttle would actually be an advantage in this case, as the front wheel could provide traction but would be more reluctant to break that traction - again, at low throttle inputs...
 
Well, with front wheel motors on any surface, the trick is not applying more power than you can handle the spin. Straight line on pavement, just a little squeak, you can romp on the power.

Sandy road, typical at the stop light, one rotation of spin is easy to control. Same for wet road. But at this point, you might stop throttling on any kind of corner. Power slides with front motors are quite possible, they just take incredible riding skills.

Snow and ice without a studded tire would get you into only wanting to throttle when going in a straight line, and modulating the throttle very carefully so you don't slide. I'm just saying once I got a bike with a rear motor, I NEVER took the front wheel motor bike out in wet muddy, or snow conditions again. Just too many laydowns. Leaving a corner stop sign, splat, its no fun. Pedal around that corner with the rear drive, then gently throttle once going straight is the thing.
 
2wd seems like a good option, really the most difficult part for me would be figuring out the ideal throttle combo. ive been doing left throttle and running a 1x drivetrain with the shifter on the right. i dont know that i would want power going to both wheels simultaneously at all times at the the same rate, I think to perfect it would take a ton of experimenting And even at that, the "ideal" setup Is likely to be different on a case by case basis, With even the condition of the trail playing a big role

To me, the run-on of most pedal assist systems make it a no no And severely affect the safety and handling for technical off roading. I actually just ordered a TSDZ2 To try out a torque sensing set up and hopefully this doesn't have that issue. for low speeds, I am thinking something thing like that With a Q 100 or Xiongda up front on throttle may be my ideal setup.
 
I ran 2WD for about 8 years, mostly dual Q100's, but sometimes a Q100 up frt and an Ezee rear.
At first I tried to control two controllers w/ one throttle by keeping the controllers close together and using a short common ground. The throttle responses never really felt smooth, I suspect splitting the signal degraded it.
Running the frt. motor thru a Cycle Analyst was a success, but that bike was stolden and I didn't want to buy another CA, so I went w/ a simple dual throttle set-up;

https://endless-sphere.com/forums/viewtopic.php?f=2&t=88304&p=1288657&hilit=dual+throttles#p1288657

This worked very well, as I explain in the link.
I always ran two complete systems, two throttles, two controllers, two batteries, thinking that if one system failed, I could ride home on the other, but, although I had to do "roadside fixes", nothing ever failed to the point where a system was dead.
The thing folks need to understand is, there is seldom a need to run both motors at the same time. The rear was the main system and I would add frt. power as desired and over time that turned out to be about 25% of the time. Consequently, the frt. batt. could be sized about 25% of the main.
Now this is fair weather street riding, off road one would use both together more often. I did some off-roading, but came away thinking, 2 mini's or even a mini and a midi doesn't make for a very gd. off-road ebike. I really think a mid-drive and a frt. mount would be a better solution.
We hear about all the advantages of 2WD, but for those of us who don't ride in snow and ice like the OP wants to do (I guess he's not coming back), those advantages are over-blown, especially when the added complication is taken into account. For me, the biggest benefit was when I upped the total power. Being able to start on the rear only (1/2 power) made the bike easier to ride without having to deal with taming the throttle response, as opposed to using a single powerful motor.
These days, one motor is enough.
 
you know, i was thinking about it some more and i am inclined to think you are probably right. nowadays with fat bikes and plus sized tires plus tubeless allowing you to drop the pressure way down the need for a 2wd may be a thing of the past in most situations. people ride fats under human power on the beach, and in snow so it stands to reason that two motors are really as needed as they may have been a decade ago when we were running 35psi on a 2.1" tire

aside from ice, where anything without studs is less than ideal , it may add more complication than what its really worrh
 
2WD on upright bicycles never made sense. It never yielded more performance; the improved reliability was simple redundancy at high complexity, and it sacrificed ability to steer and keep the bike upright.
 
Actually, 2wd does make sense. Just not for traction on snow or ice. But with good traction, I could corner quite a bit faster if I could pedal up grip on the rear wheel, and then at apex, grab harder on the front wheel. This is part of why I commuted on front hub motors for so long. It was that nice. But only on dry, clean pavement corners. And only with power below 3000w. at 4000w, I kept power sliding in corners.

Dirt however, sucked with front motor. You had to pedal too hard because you couldn't grab but so much with the front wheel. Like I said, power slides with front motors took incredible riding skills. Once I started working at home, where I have endless dirt riding all around my house, that was the end of the front hub commuter bikes.
 
dogman dan said:
But only on dry, clean pavement corners. And only with power below 3000w. at 4000w, I kept power sliding in corners.

I'm not really following this quote. Do you mean only if we artificially cap output to 3kw, then FWD/2WD makes sense?

I don't mean to be pedantic, and I agree that FWD/2WD is fundamentally less of a hindrance at decreasing power levels where load transfer is therefore lower, but I don't see a concrete explanation for why it is superior to RWD.

I was going to post this as a direct reply to the OP, but equal power front & rear would be a waste and not performant, second only to FWD. The correct way to do 2WD would be to size the auxiliary front power as some varying and small fraction of the main rear power based on available front tire traction, considering longitudinal load transfer, cornering, and a safety factor to prevent front washout. Since upright bicycles can easily transfer 100% of the load to the rear, this fraction trends towards zero...
 
It trends towards more than 50%, if you are using front brakes correctly, as you dive into a corner at high speed. And you don't wheelie on acceleration, if the power is coming from the front wheel. But yes, in general, I still agree put most of your power on the front. If it was that great, motorcycles would have front powered wheels. Some do actually, but most don't.

Your cap might be different than mine, for front hubs. But what I was trying to say was that front hubs work great till you lose traction. On really clean really dry pavement, you can put a lot of traction down on a front hub and it feels great. But if conditions, such as snow or ice or dirty pavement make you lose front traction, then you just can't use the motor much, or you start power sliding and crashing. So I still say no front hub for snow and ice, if a rear hub is possible instead. Might be a rocking thing though, 2 motors, for the dry! I never did 2 motors, just motor in front, and pedal in a very high gear in back. So Id have traction with both wheels on corners, as I did my commute.


What I was trying to do at the time I had 4000w front hub, was beat gasoline powered bikes in a race, on a go kart track with tons of tight corners per lap. So the surface was perfect, and the 72v 40 amps setup worked like a dream. However, when I went to 110v 40 amps, I began to get the loss of traction in corners at full throttle, and started crashing a lot more. That race, I crashed in the heat race but still qualified for the main. In the main I got a flat front tire, which caused enough drag to make me run enough power to melt the motor before the end of the race. I never won that race, but I did well enough to make the gassers go buy bigger, more powerful motors the next year.
 
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