well sounds like most posting here arent much better than the roommate
your not goin to get anywhere stoopin to his level ( only an idiot will argure with an idiot ) if ya argure with him or try to show him up it will just cause more friction.
so when he says somethign negitve about biking just say "Yea your Right" and go on about what you were doin,

try and get him to go for some short rides with ya
find a cheep bike someplace and give it to him(maybe hes never had one), see he probably has been taught that bikes are for kids ( i was ) they are a toy,
go to a couple of drag races with him,
if you show some interest in what he does maybe he'll do the same