If I had to guess, he's someone who laughs at the likes of wannabes/uber freds/non-mountain biker poseur types like you.

That's just a guess though.

Maybe he has a thing for corpulent fakers who collect bikes in order to tootle along on tame gravel paths so they can exclaim, "I is mountain biking!" (and then attempt to post authoritatively about their mountain biking experience).

There is humor to be found in many aspects of "mountain biking."