Interesting off the shelf transmission

[travis]

My wife recently purchased an 80s vintage cruiser bicycle at the local Goodwill -- a Murray Monterey. She said it was a three speed, but I said no way since there were only two sprockets. Closer inspection revealed a neato planetary gear box in the wheel hub. The exploded view here made me think they were super pricey:

http://en.wikipedia.org/wiki/Sturmey_Archer

but they start at $60:

http://www.permaco.com/en-us/dept_8.html

The higher end ones even have an integral brake. They are certainly robust enough and already have a #35 sprocket and straight forward mounting. The gear ratios are not stellar (1:0.75, 1:1, and 1:1.33), so perhaps this is more a discussion of a cool arcane technology then a possible FIRST part, but I am glad to have them in the back of my head should the need arise.

Travis