[ianbicking]

I'm looking at the third one down and wondering: why aren't all-wheel-drive bikes a thing? (Well, steering...)

I guess there is such a thing: http://christinibicycles.com/ – sounds pretty complicated: 'A handlebar-mounted switch controls the AWD “shift on the fly” clutch. When the clutch is engaged, the rear spiral gear interlocks with the rear hub and power is transferred via internal shafts to the forward spiral gear set, which drives the CHRISTINI freehub. Due to a slight gearing differential, the front wheel is not actively powered on smooth level ground. However, the moment the rear wheel slips, power is instantaneously transferred to the front wheel. Similarly, the moment that the front wheel decelerates, as in hitting a rock or starting to wash out in a corner, power and traction are transferred to the front wheel.'

Makes me wonder if you could make an electric-assist bike where the assist was on the front wheel, thus saving all the complicated mechanical power transfer. I also suspect driving the front wheel feels crazy on a bike and I just don't realize it.

[douchescript]

My electrib bike is AWD. Electric in the front and mechanical in the back. Very good for recovery on a patch of ice, impossible with just back wheel drive.

[ianbicking]

What does it feel like when you aren't peddling and it's just front-wheel drive?

[douchescript]

It doesn’t drive if no peddling, legal stuff here in sweden.

[stefan_]

Crucially a front wheel losing traction isn't recoverable. So it has rained, you ride over a bunch of leaves and that is the moment the electric motor decides to apply power, you're going down immediately.

And why in the first place, there is no benefit.

[dancek]

Well, that depends. It's easy to lock your front wheel for a split-second on gravel without falling---you just need to keep your balance while the wheel is locked. If there's a certain amount of kinetic friction front wheel drive could even make it possible to recover after balance is lost.

AWD (electric front drive + pedaling) is actually quite common among hobbyists in areas that often have snow (say, Scandinavia). It's as useful as it is for cars.

[bhandziuk]

Locking your front wheel is usually 1) very difficult 2) non-recoverable unless you're good on a bike. If you lock you're front wheel going any speed over walking pace you'll probably go down. If you lock it up in the wet you're almost guaranteed to go down fast.

If you're riding uphill rear wheel drive on a bike is great because that's where you're weight is. The front wheel doens't have much. Put power into the front wheel and it might spin.

Put power through the front wheel while going downhill...well there was not need to because you don't need to have a power boost because you're going downhill.

I'm unconvinced except maybe deep snow with big fatty tires.

[meej]

> Makes me wonder if you could make an electric-assist bike where the assist was on the front wheel, thus saving all the complicated mechanical power transfer.

This exists, it's called the GeoOrbital Wheel. It converts your bike to electric just by swapping out the front wheel. Pedaling is optional, so it's actually more than just an assist, it can operate in a fully electric mode. http://www.geoo.com

I own one and I'm very pleased with it.

There are also a bunch of front wheel e-bike conversion kits on Amazon, last I looked.

[rhinoceraptor]

I can only imagine how much of a nightmare working on one of those bikes would be. Plus the efficiency losses and extra weight, I don't think AWD bikes will ever be common.