I'm still recovering from this Lurgi, all snuffles and sore throat. I've upped my medication to include honey, lemon and brandy, and it's slowly winning the battle.
I bought a torque arm to go on bike.3. A torque arm transmits the rotational force (torque) from the hub motor to the bike frame. Without a torque arm, you're relying on the front fork cut-outs to hold the motor, and they aren't designed for it, they're designed for a front wheel that just turns freely. The possible downside is that the torque from the motor distorts or cracks the front forks. the worst case is that you're whooshing along at 15 mph, then suddenly you don't actually have a front wheel. You can imagine the pain.
The torque arm that I bought, won't slide over the flats on the axle. I thought about filing it a bit, but I got an idea from a discussion group. A spanner.
So I fitted a 10 mm spanner over the axle flats, and jubilee-clipped that to the front fork. Here's a picture;