Out of the other suggestions, mostly, I am going to list the ones that are actually available to be registered.
werewolvesonwSPAMMED URL (that actually surprised me)
igottadamnflattire.com (that didn't surprise me)
sidecarofterror.com (again, not surprised; but an interesting domain name)
runplumboutofgas.com
nohelmetrequired.com (actually surprised this was available)
howdobikerseat.com (would have been utterly shocked if that had been taken)
organdonormovies.com (not surprised, but it is an interesting name)
sidehackers.com
badmovierider.com (btw, sleazyrider.org is available)
wildeasyrider.com
zombiebikers.com (was surprised)
chromeraiders.com
wheelsofsteel is not, but wheelsofchrome.com is
TwoLaneBodySlide.com is available