It's $.03/mile to .10/mile depending on how long it's been since I bought a bike. This year including the bike I bought myself for last Christmas, some new tires for two bikes, chain lube, chain, some shorts, brifter set, and a multitool it comes to about 12 cents, but those tires (not to mention the bike and brifters) will last more than a year so that will drop next year.