Wow! I plugged the batteries into the chargers three hours ago, and on a whim popped one into the silver bike before heading to bed, and it worked great! That was the first time riding an ebike, and I've got to say it was a blast. Good thing it was dark or my neighbors would've thought I'd gone over the deep end what with the big smile on my face! (then again, some neighbors think I've already gone over, but that's another story.)
The LaFree's controller only engages the motor while the pedals are moving. You don't need to be working hard at it; just a token moving of the pedals is all that's needed. The LaFree also has the motor/gearbox integrated with the crank, so the gearing on the freewheel works with the motor. Gear down going uphill for more torque; gear up on the flats for speed. There's no speedo on it (yet) so I have no idea how fast I was going, but I'd guess it was close to 20mph. I know I'd have to be working a bit to go that fast without a motor.
I've heard many on this forum mention how quiet the Golden Motors are (Silence is Golden, and Goldens are Silent), so that is something I look forward to. The LaFree is a bit noisy. Not 2-cycle-type noisy, but there is more than a hum there. The motor has brushes, so that makes a bit of noise, plus I would imagine the gearbox makes some of its own noise. The motor's shaft runs in line with the wheels, so there must be some sort of bevel gear in there to reorient the motor's rotation.
Very, very pleased that one of them works without much effort on my part. And at the price I paid for them (nada), I go to bed a happy guy.
I'll pull the wheel off tomorrow & measure the rear dropouts, but since it's got a standard 7-speed drivetrain, I'd guess it's a standard 130-135mm spacing. And with an aluminum frame, coldsetting is out.
And yes, the wheels are 26" diameter. Where'd you get the 15"?