How to install radioshack Super Speed 9-18VDC Hobby Motor?

I need to somehow mount a small gear on it. This gear would be a smaller bicycle gear. Since it is aluminium, i can weld it, any ideas???
Update: LIKE THIS

http://www.radioshack.com/product/index.jsp?productId=2102827&cp=2032058.2032230.2032271&parentPage=family
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