All-wheel drive electric bicycles

[LockH]

All-wheel drive electric bicycles: double the motors, double the fun!:
https://electrek.co/2018/04/30/all-wheel-drive-electric-bicycles/

Starts:

Electric bicycles are quickly working their way out of the shadows and into the mainstream cycling world as e-bike sales continue to grow. E-bikes combine the draws of cycling, including low-cost, fun and traffic-free commuting, with the advantages of cars and motorcycles – namely, that the vehicle does the work for you.

Great for more than just utilitarian uses, electric bicycles are also excellent for pleasure riding. The addition of an electric motor ratchets up the fun on everything from bicycle trails to snowy slopes and sandy beaches. If one electric motor can have this much impact, imagine what two motors could do!

Includes:

Why buy when you can DIY?

As you might have noticed, the price for these AWD electric bicycles is fairly high, in large part due to their rarity and lack of competitors. However, if you’re already handy with a wrench and capable of basic bicycle maintenance tasks, you could easily build your own AWD bicycle simply by converting a standard pedal bicycle into an electric bicycle with two motors.

To do so you’ll need to start with a donor bike. If you already have an old mountain bike or other strong bike lying around, you’re all set. If not, you’ll want to find a sturdy bike, preferably with a steel frame and fork. It doesn’t have to be expensive.

8)

 

[AWD]

Two wheel drive made easy and with a lot less weight, cost and complexity involved is to just use a front hub motor and pedal! I have two bikes setup like this and it works a treat.

 

[MadRhino]

Riding on loose terrain, makes it interesting to build a 2wd bike, for traction. Otherwise, it is redundance, only adding weight since the extra power can be obtained with a rear motor alone.

 

[Alan B]

On loose surfaces pedaling causes torque variations that can result in loss of traction, whereas smooth torque from a motor works better. Smooth torque on both bicycle wheels works extremely well on loose material, better than one motor with or without pedaling.

 

[billvon]

I've often thought about doing a mid drive with a small DD front motor (like an NSM) for regen and "loose sand conditions" only. Still, a 5 pound penalty for a minor increase in performance/range.

 

[liveforphysics]

AWD could only hurt off road or on road performance VS just having the right sized motor in the rear. It's for the same reason just a good front brake gives a vehicle the same stopping distance as a front and rear brake.

RWD of adequate thrust is the key to off road or on-road.
[youtube]GoxJP306ZE0[/youtube]

 

[MadRhino]

On loose surfaces pedaling causes torque variations that can result in loss of traction, whereas smooth torque from a motor works better. Smooth torque on both bicycle wheels works extremely well on loose material, better than one motor with or without pedaling.

Yep. Loose sand or snow, mud too sometimes, are making you wish for some power on the front. Otherwise, a front motor is a handling handicap.

 

[artisanstone]

AWD could only hurt off road or on road performance VS just having the right sized motor in the rear. It's for the same reason just a good front brake gives a vehicle the same stopping distance as a front and rear brake.

RWD of adequate thrust is the key to off road or on-road.
[youtube]GoxJP306ZE0[/youtube]

What about the Christini type system? Sure it adds weight and complexity, but I think it also adds the ability to be quicker in certain situations. If you're not familiar (which you probably are), basically the rear is powered at a higher speed than front. Front has an overrunning clutch so only comes into play when rear is spinning.

Pretty simple and apparently has great results offroad.

 

[liveforphysics]

It might help something like starting from a stop in deep sand, but anytime you could choose to just add that same drive thrust to the rear wheel my hunch is the vehicle performs better.

I only know one guy who had a Christini drive (Chip Yates), and he never raced with it connected because it was so sketchy to have the front randomly spinning up.

 

[artisanstone]

I was thinking more about starting on steep uphill. That's the situation that makes sense to me. No personal experience at all though. It's been really interesting reading and learning here. I know you are one of the bigger content providers. Thanks for that.

 

[MadRhino]

Uphill acceleration is the situation where all the weight is on the rear, making a front motor useless, and even a nuisance for its power can make the front wheel wash out at any steering attempt.

To make it clear, a good rider need to be in deep sh*t to wish for a motor on the front. :wink:

 

[liveforphysics]

[youtube]Eo77vgUK6iQ[/youtube]

Even in corner cases like sand, or ultra extreme low grip surfaces like water, just having the rear wheels alone is perhaps still always most optimal. That said, I could believe some corner case in riding exists where it could be beneficial, maybe deep snow or something?

 

[MadRhino]

...
Even in corner cases like sand, or ultra extreme low grip surfaces like water, just having the rear wheels alone is perhaps still always most optimal. That said, I could believe some corner case in riding exists where it could be beneficial, maybe deep snow or something?

Once you got it started and lifted out of sh*t with speed, front traction is making no sense of course. Even in deep snow, the only problem is to gain enough speed to make the bike rideable. That can be achieved with spikes, if the situation will persist. Yet we are not normally riding deep snow, for there are always better alternatives. Snowmobile trails are fine to ride, even snowshoes trails that are many in the mountains here, are making a good surface.

For slow maneuver in loose terrain, I can understand one building 2wd. I wouldn’t.

 

[motomech]

I've been using 2WD for years and I'm afraid folks miss it's biggest advantage completely.
It's not traction, although unless one is an aggressive and routinely lofts the frt. whl., it works well for moderate TRAIL riding.
And it's not system redundency, although if I ever had a system failure, I guess it would be great.
It's biggest benefit is being able to keep the power on the main (rear) motor low to facilitate smooth throttle response w/out having to resort to complicated "throttle taming". It also helps a simple PAS system interface w/ the rider.
But, at the same time, there is the option to make a 1K Watt bike, a 2K watt bike, giving in effect, 2 ebikes.
I use a very simple side by side thumb/half-twist 2 throttle set-up which is intuitive and easy to use, although I usually stay on the PAS for the rear motor and just "thumb" in the frt. motor when taking off from a standstill or any time I want a little more omff.

 

[liveforphysics]

If you have a real torque control FOC controller, you've got buttery perfect throttle control of just the rear motor.

 

[Alan B]

So many times, in real life, 4WD solves the problem. Not for racing on surfaces with good traction, perhaps, but for going slow, especially towing a load, with control, in traction limited conditions. In the same conditions folks with 2WD have to race, bounce, damage their vehicles to bash their way through. They may get through faster, or they may fail totally. 4WD just glides through, no hassle. If the 4WD has trouble getting through the 2WD typically fails all together unless they have massive excess power and don't mind doing crazy things to their equipment.

Been there many times myself, on both sides of the equation.

Watched RC cars racing years ago. The 2WD cars could not compete with the 4WD. Don't know all the details, but the differences were huge.

If front wheel drive was useless then our good friend's front wheel drive racing car would fail to be competitive. It seemed to work fairly well, so front wheel traction must have some value.

There are times when spending some weight to gain traction and control is worthwhile. Perhaps not so much for the speed daemon, but for some others it has value.

2WD ebikes are not for everyone. There are two use cases where I have found value in 2WD on an ebike. One is where traction is limited. Loose dirt, etc, with moderate power. If you had enough power to jet out loose material perhaps 2WD would have no value, but if you want to go slower without tearing up the road the 2WD does a better job. The last thing we want to do with our ebikes is to tear up the terrain. A 2WD ebike damages the terrain less than a larger single motor ebike ripping up the trail.

The other case is where we want to use standard ebike motors. Two small or normal size ebike motors make a huge improvement over one. Doubling the power without buying a huge heavy hubmotor is an amazing improvement. The weight distribution is better, and the appearance is more ebike like. Regular bicycle tires can handle the power, whereas a big hubmotor may require much tougher tires to hold up well.

Yet another use case is when the reliability of a second motor is wanted.

 

[liveforphysics]

If I'm in a riding situation where the front wheel has weight on it, I'm typically using it for either every bit of braking traction and/or every bit of cornering traction it can offer up to the threshold of it slipping out. Otherwise if I'm trying to accelerate at any point in my ride I'm in a state of wheelie management, and bike thrust is limited by it's wheelbase geometry supporting not flipping over.

I respect its possible to ride other ways than this, but haven't seen them yield impressive results at the track.

[youtube]DaZiKy-xzZI[/youtube]

 

[MadRhino]

I like to compare bikes and horses. Those with a powerful hind and a light front, are moving with elegance and agility.

Yet, there will always be some riders who prefer to compare bikes and bulls, for their own purpose.

 

[teklektik]

Bikes, like horses, are built many different ways to serve many different purposes.

 

[MadRhino]

Bikes, like horses, are built many different ways to serve many different purposes.
...

Yep. Some are more suitable to carry beer, than riding.