Generally front wheel drive isn't ideal, partly because of risk of slipping on hills. I have remarked before that this is different on a tandem where weight distribution is different, and you gain the advantage in some slippy conditions of two wheel drive (front motor, rear rider effort).
I found one more advantage yesterday. If you are riding up a slippy and frosty grass incline without a stoker on board the front wheel gives much better grip.
I found one more advantage yesterday. If you are riding up a slippy and frosty grass incline without a stoker on board the front wheel gives much better grip.