I Also love Mountain biking, and while there's no problem putting one in the plane (The wheels get cable tied to the roof inside the cabin), there is a problem to get my wife's bike in there as well.
When I brought it up with the factory of the Bushbaby / Kitplanes for Africa Safari, Stefan Coetzee said that he would be concerned with flexing forces as the speed built up, risking the wing developing washout or increased angle of attack or flutter?
I realize that Kitfox fuselage strength is very high compared to other makes, but are my thinkings valid?

http://saplanes.co.za/

Looking forward to a solution being found.
Reid