Setting the checked attribute in a dynamic way doesn't seem possible.

As per html spec, checked="checked", checked = "junk", checked="" all lead to a checked radio button. Just the presence of attribute is enough.

So it leads to following problems. I guess the workaround would be in Javascript?

//sfdc is smart enought to removes checked attribute in the rendered html because it is empty
<input type="radio" name="r1" value="Bike" checked="" /> 

//SFDC renders checked="" in html, hence button is checked. SFDC should get rid attribute as it does above
 <input type="radio" name="r1" value="Bike"  checked="{IF(false,'checked' ,'')}" /> 

//So try to get rid of the attribute itself dynamically. However SFDC does not allow the next two syntax  in API 19.0 with complile time error - Element type "input" should be followed by either attribute specifications, ">" or "/>". Seems like it wants attribute=value syntax. It allows it at compile time in 16.0, but end users get the same message at run time, which is not acceptable. 
 <input type="radio" name="r1" value="Bike"  {!IF(false,'checked' ,'')} /> 
 <input type="radio" name="r1" value="Bike"  {!IF(false,'checked=\"checked\"','')} />