2 motors, 2 controllers, 1 throttle + 1 switch

[ZapPat]

Consider that even in voltage control mode that the no-load speed is always quite a bit higher than the loaded speed, so if the motors are anywhere near matched, they will share the load evenly.

Hum... I guess this is a good point as long as the two wheels are not traveling at very different speeds. I'll have to take Knuckle's advice and try both types of controllers (voltage mode and torque mode) with the same bike and motors, and see how different the handling is between the two. Now I'll I would need is a data logger that could measure two currents and voltages at the same time, to satisfy my inquisitive scientific side.

 

[Affliction]

I've been running a dual hub setup for the last 2 years and to simplify I use two throttles!
You don't want to be powering the front too much on a icy corner and conversely in a foot of snow you want to be able to control both motors independantly so as to stay upright.

 

[The Stig]

lose traction on the rear wheel in a straight line, you would want to cut power to the rear and add power to the front. But do that in a turn, if the rear wheel was slipping sideways, the sudden regaining of traction can cause the bike to flip over, and it's best to let the back wheel keep slipping as long as the angle can be maintained.

Lose traction on the front wheel, and you would want to kill all power to the rear smoothly, as you lose all ability to steer and balance when the front slips. But if you're trying to climb a hill, you might want it to lock the rpm of both wheels and let them slip

I like the idea of traction control and I'm going to defend it, even though we probably won't see such systems for many years.

There are traction control systems for motorcycles that could be implemented in ebikes one day. These systems cut back on throttle as soon as wheel slip is detected to regain traction. From what I understood this all happens in a matter of miliseconds so theres no way the bike would flip over when traction was regained.
http://www.webbikeworld.com/BMW-motorcycles/stability-control/

Automatic Stability Control prevents the rear wheel from spinning uncontrolled when accelerating all-out and thus avoids any loss of side forces and stability which otherwise would make the rear wheel swerve out of control.

There is also this system that detects spikes in engine RPM and then cuts back on throttle to regain traction.
http://www.motorcycle-usa.com/543/2...z-Performance-Z-Fi-Traction-Control-Unit.aspx

Unlike a wheel speed sensor equipped setup, this one is a rate-of-change system. Basically, the electronics have a specific engine acceleration value. If it detects an increase in that value (tire spin), then engine power is reduced by cutting the spark to one or more of the cylinders until the original acceleration value is met.

I don't know about you guys but I would kill for a traction control system if it could keep my wheels from slipping and me from falling over in slippery conditions. It would eliminate a lot of danger from biking in wet and icy weather.
I have slipped and fallen while taking a turn on a road covered with wet leaves. Thankfully I have not fallen on ice yet even though its been a harsh winter and I commute by cycle.

 

[ZapPat]

This is what you want to avoid slipping, The Stig!



Both your links are broken (incomplete URL's) so I'll poke around the sites to find the pages later, but they sound really neat, pretty much the kind of intelligent 2WD I was imagining by your description. And much much easier to do with two electric motors compared to a gas engine! Thanks!

Pat

 

[The Stig]

Links are fixed! Thanks for pointing that out.

That looks like a serious ice tire! A bit too much of an ice tire for my uses. I commute by bike and it's still under pedal power. As of yesterday I'm the proud owner of a pair of these:

This model only has studs on the outside so that I can leave them on there the whole season. With 35psi of pressure the studs don't touch during normal straight line rolling on tarmac but as soon as I push the brakes my front tire gets squashed and the studs make contact. The equivalent happens during uphill pedaling, my weight on the back wheel squashes the tire so the studs make contact. It also has a real deep tread for snow and slush. On non-icy days and routes I put more pressure in them for less stud wear and rolling resistance. Good grip through the corners. Perfect set up for commuting I think.

A good set of studded tires, traction control, 2 wheel drive, and four point riding could make a bike better in snow and ice than a 4x4