This one isn't a flip flop hub - a flip flop for anyone who doesn't know is right handed OR left handed threads on both sides of the hub. The purpose of it is for riders who do not want the ability to change gears on the fly. Dependant on the terrain, a rider on a flip flop hub would actually turn the wheel backwards to take advantage of a different sprocket that is more or less only stored on the left side of the hub. These ARE cheaper than the "Dual Drive" hubs, but I would rather use the proper hub for the job. I did not use a flip flop, but I talked to someone who HAS done it on a flip flop. How he did it was by welding a lockring to the sprocket and using a second lockring to keep it from backing off on acceleration.
Also, I have heard of people using Disc Brake hubs - that is another common hub in which you can get the same effect, and they are more common than these "Dual Drive" hubs.
Mine on the other hand, I just call this hub a Dual Drive hub, as you can accelerate the bike from the left or right side of the hub.
The hub was purchased from Staton-Inc, price tag at about 108$ to get it to my door.
The flange with the sprocket was from a BGF "HD Axle Kit". I disabled the springs and JB Welded the bearings, so that I now have a threaded sprocket that I don't need a pullstart for.
It is necessary to RED locktite the threads and tap it tight with a large screwdriver and hammer if you choose to take this same route of disabling the freewheel so as to not use a pullstart. The purpose of that is, when you compression start it torques the freewheel backwards - spinning it off. Without locktite, it will back off and cause damage to the bike! There is no chance of this happening once the motor is engaged, as the left side of the hub has left handed threads, when accelerating from the motor it will tighten it down.
If you have a pullstart, then by all means - leave that freewheel intact.
It's fairly simple enough to get everything going!
I'm not a fan of Grubee motors, but I do like that they sell two different HD Axle Kits. One is with a freewheeled sprocket, the other is just a threaded flange without a freewheel.
http://www.grubeeinc.com/USA/HD Rear Axel kit.htm
Check out this link, there is Model 1 and Model 2.
I saw it last night, and I can't find it tonight to post a link! -_- There is a popular retailer who sells ONLY the flanges. Of course, I can't find them. Granted, they were the freewheeled flanges, but also, they are the only people I've seen that sell them standalone. I will continue to look for them and post here when I find them.